US3740145A

US3740145A - Method and apparatus for sample analysis by atomic spectroscopy

Info

Publication number: US3740145A
Application number: US00071774A
Authority: US
Inventors: D Mitchell
Original assignee: Technicon Instruments Corp
Current assignee: Bayer Corp
Priority date: 1970-09-14
Filing date: 1970-09-14
Publication date: 1973-06-19
Anticipated expiration: 1990-06-19
Also published as: GB1354977A; NL7112536A; FR2107508A5; AU454603B2; AU3289271A; DE2144642A1; BE772218A; IT961044B; SE379856B; CA949349A

Abstract

New and improved method and apparatus for the analysis of samples by atomic spectroscopy are provided and comprise sample atom production means taking the form of body means having a generally central sample chamber extending generally longitudinally therethrough, and heating means for heating said chamber and adjacent areas to convert said sample to atoms. Sample stream generation means in the nature of drop generator means are operably associated with said body means at the lower extremity thereof and are effective to generate a stream of sample drops of substantially uniform size for upward passage through said body chamber to result in a formation of a concentrated atom cloud or sample volume of the sample atoms of interest above said body means. Means are provided to modulate the formation of said sample volume by said sample drop stream to provide for more accurate read-out of the sample atom concentration of interest. Means are also provided to enable the simultaneous multielement analysis of a sample by atom spectroscopy and comprise a plurality of drop generator means which are operable to generate a plurality of sample drop streams for passage through said body chamber to form said sample volume, and means are provided to periodically and alternately deflect said sample drop streams from passage into said sample volume to substantially eliminate signal interference. As disclosed, the new and improved method and apparatus of the invention are particularly adaptable for use in automatically operable sample supply, treatment and analysis means which are operable to automatically analyze a series stream of a large plurality of different samples on a continuous flow basis.

Description

United States Patent Mitchell.

[ METHOD AND APPARATUS FOR SAMPLE ANALYSIS BY ATOMIC SPECTROSCOPY [75] Inventor: Douglas G. Mitchell, Tarrytown,

[73] Assignee: Technicon Instruments Corporation,

Tarrytown, N.Y.

[22] Filed: Sept. 14, 1970 [21] Appl. No.: 71,774

OTHER PUBLICATIONS Dickinson et al. Analytical Chemistry, Vol. 41, N0. 8, July 1969, pages 1021-1024. H. V. Malmstadt, The Encyclopedia of Spectroscopy, ed. by George Clark New York, Reinhold Publishing Corporation, 1960, pages 12-18. Schneider et al., The Review of Scientific Instruments, Vol. 35, No. 10, October 1964, pages 1349 & 1350. Lindblad et al., J. Sci. Instruments, Vol. 42, 1965, pages 635-638. Lindblad et al., The Review of Scientific Instruments, Vol. 38, No. 3, March 1967, pages 325-327. l-lieftje et al., Analytical Chemistry, Vol. 40, No. 12, October 1968, pages 1860-1867. I-lieftje et al., Analytical Chemistry, Vol. 41, No. 13, November 1969, pages 1735-1744.

Primary Examiner-Rona1d L. Wibert Assistant Examiner-F. L. Evans Attorney-S. P. Tedesco and Stephen E. Rockwell 1 11 3,740,145 1 June 19, 1973 [57] ABSTRACT New and improved method and apparatus for the analysis of samples by atomic spectroscopy are provided and comprise sample atom production means taking the form of body means having a generally central sample chamber extending generally longitudinally therethrough, and heating means for heating said chamber and adjacent areas to convert said sample to atoms. Sample stream generation means in the nature of drop generator means are operably associated with said body means at the lower extremity thereof and are effective to generate a stream of sample drops of substantially uniform size for upward passage through said body chamber to result in a formation of a concentrated atom cloud or sample volume of the sample Means are also provided to enable the simultaneous multielement analysis of a sample by atom spectroscopy and comprise a plurality of drop generator means which are operable to generate a plurality of sample drop streams for passage through said body chamber to form said sample volume, and means are provided to periodically and alternately deflect said sample drop streams from passage into said sample volume to substantially eliminate signal interference. As disclosed, the new and improved method and apparatus of the invention are particularly adaptable for use in automatically operable sample supply, treatment and analysis means which are operable to automatically analyze a series stream of a large plurality of different samples on a continuous flow basis.

19 Claims, 15 Drawing Figures United States Patent 1 Y [11'] 3,740,145

Mitchell I [451 June 19,1973

CONCENTRATION Patented June 19, 1973 3,740,145

9 Sheets-Sheet 1 iaa'cissms 2 28 V CIRCUITRY AND 66 6 2 fi P3672? SUPPLY (DETECTOR fi-AlRAND FIG? FUEL POWER 48 I 49 22 62 [26 J60 I -;5'- LAMP POWER LAMP SUPPLY mmsoucen 38 I3 42 DOUGLA o. MITCHELL HY I A l"l()hNla' Y Patented June 19, 1973 9 Sheets-Sheet 2 MW T .T U S M 0 A ON T 7 NE C GC E IORAAM T s u E E R D 8 P 6 2 I g 6 8 2!\ M T 98 \woo 96 T 92*? as FROM SAMPLE SUPPLY MEANS 2| FROM SAMPLE SUPPLY ems 2| SUPPLY MEANs Patented June 19, 1973 3,740,145

9 Sheets-Sheet 5 \sw|TcHme I w h DEVICE SIGNAL azza w l I AND I REAAEE:X N%UT l 62 I 1 68A LAm POWER 7 DETECTOR SUPPLY r v 608 g 70 26 H4 '89 Hz MQAQA F165HO X ea :2: A l sz uo 5s 94 49B 4:5 8 43A 96 s 98 mom SAMPLE FROM SAMPLE SUPPLY MEANS SUPPLY MEANS Y FOR SAMPLE FOR SAMPLE IN PHASE B t IN PHASE A 22B 22A 49\ \-|oo I02 HO FIG. 6 I06 I08 INEIIERCEJAMS 43 .1 SUPPLY MEANS FROM SAMPLE gg n DOUGLAS 6. MITCHELL Patented June 19, 1973 9 Sheets--Sheet SIGNAL PROCESSING CIRCUITRY AND READ -0UT MEANS R nu T c. E T E. D

LAMP POWER SUPPLY JPN FROM SAMPLE SUPPLY MEANS Patented June 19, 1973 LAMP POWER SUPPLY mom SUPPLY OF SAMPL E AT ORIGINAL CONCENTRATION RETURN 9 Sheets-Sheet 6 V l L6 swn'cumd DEVICE SIGNAL pnocsssme AND READ -OUT MEANS I l I I CIRCUITRY I l l l I a DETECTOR FROM DI LUTED "SAMPLE SUPPLY MEANS 1M PS3 I wk DOUGLAS G. MITCHELL RETURN A TTuRxlc Y Patented June 19, 1973 9 Sheets-Sheet 7 fL i M l: swncmus DEVICE I 72 l I f I SIG'NAL PROCESSING I I cmcun'mr 1 AND I READ-OUT I I MEANS l 1 68A DETECTOR 68C I l I 52\ -50 Y H .124 I GD /49ABCD |62 I F L' E |i MO D U IFETED P SIGNAL GEN. J 2M 43 I 2mm SAMPLE SUPPLY MEANS 22 DJYILYI'UR.

DOUG AS G. MITCHELL Patented June 19, 1973 9 Sheets-Sheet 8 H6 SWITCHING oswcs FIG/3 TIME 72 SIGINAL AND 0-- OUT MEANS i PROCESSING I CIRCUITRY I REA DETECTOR INXYICY'I'UK DOUGLAS 6. MITCHELL m l A 2 0M SAMPLE v PPLY MEANS 2| L FR LAMP POWER SUPPLY METHOD AND APPARATUS FOR SAMPLE ANALYSIS BY ATOMIC SPECTROSCOPY BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to new and improved method and apparatus for sample analysis by atomic spectroscopy and, more particularly, to such method and apparatus as are particularly adapted to the automated quantitative analysis by atomic spectroscopy of a series of blood serum samples with regard to a variety of metal salt elements or constituents thereof.

2. Description of the Prior Art Although a wide variety of methods and apparatus are known in the prior art for sample analysis by atomic spectroscopy it may be understood that, in general, no prior art method and/or apparatus are known which can provide for sample analysis by atomic spectroscopy on the consistently highly accurate and reliable basis required in many areas of todays increasingly sophisticated technology. a

More specifically, a major problem area regarding the atomic spectroscopy analysis methods and apparatus of the prior art is constituted by the requisite partial conversion of the sample to atoms to form the requisite atoms of the constituent of interest for analysis by atomic spectroscopy. The prior art apparatus most often relied upon for effecting this requisite sample atom formation generally take the form of pneumatic nebulizer-burner means which function to convert the liquid samples for analysis into an aerosol consisting of sample drops of widely inconsistent size up to, for example, 80 m in diameter, the removal of some portion of the larger drops in a cyclone chamber, or through the use of a baffle, and the mixture of the remaining drops with the flame fuel gas and passage through the burner gas supply holes of this mixture into the flame. Solvent evaporation and the like, and numerous chemical reactions, occur in the burner flame, with the net result being that the sample element or constituent of interest is partly converted to atoms in the flame to enable atomic spectroscopic flame analysis.

The disadvantages of the construction and method of operation of such prior art pneumatic nebulizer burners are many and significant and include the following:

a. Sample consumption is inordinately high in the order, for example, of 2 mls per minute of which approximately 0.1 ml per minute reach the flame and only approximately /001 ml per minute passes through the volume of the burner flame observed by the apparatus detector means with resultant loss of approximately 99.9 percent of the available sample.

b. Fuel gaS consumption is inordinately high and thus increase the unit sample analysis cost.

c. The sample drops are of widely varying sizes, as set forth hereinabove, and, since it takes longer to conmeasurements by observation at a relatively low point in the flame in order to provide for an adquate signal-noise ratio. Although observation at a relatively low point in the flame is normally desirable, it may be understood that under the described flame and sample drop size conditions the same is of particular disadvantage because there are sample drops at this low point in the flame which are still sufficiently large to cause Iligllt scatter with resultant false signals and attendant inaccuracy, and this problem applies to both atomic absorption spectroscopy and atomic fluorescence spectroscopy.

d. The relative dispersion or inconsistency of atom fonnation throughout the flame will, of course, preclude the formation of a practicably observable flame volume of particularly high atom concentration, whereby the provision of truly high apparatus sensitivity and/or accuracy is rendered substantially impossible.

e. Many of the sample drops will reach the outer oxidizing zone of the burner flame and, in the event that metals in the nature, for example, of Al or Ti are present in high concentration in the sample, will result in the formation of oxidized particles in the flame. These oxidized particles can also cause light scatter with attendant false signals, and can hinder the formation of the other atoms of interest, both of which can cause systematic error.

f. The wide distribution of the sample drops throughout the burner flame at points of varying chemical environments in the latter will result in varying degrees of chemical interference with attendant reduction in analysis accuracy.

g. The sample drops leave the burner exit at a relatively high velocity to pass through the burner flame rapidly, with resultant low sample residence time in the flame and attendant significant decrease in apparatus sensitivity and accuracy.

h. The sample drops leave the burner through the same exit holes as the flame fuel gases which, in instances wherein the sample has a relatively high solids content, can result in particle deposition in and on the exit holes with resultant burner clogging, so as to require regular burner supervision and periodic burner cleaning. Further, in the event that the burner holes are made large enough to substantially prevent clogging, the serious problem of burner-flame flashback then arises.

. The high rate of sample consumption, discussed hereinabove, gives rise to a high rate of solvent and water evaporization'and expansion, with resultant formation of burner flame turbulence and attendant further decrease in flame stability and apparatus accuracy. In addition, flame turbulence results in relatively wide flame temperature variation and results in relatively wide variation in atomic emission signals.

j. The construction and manner of operation of pneumatic nebulizer burners render substantially impossible the precise, periodic interruption of the flow of the sample drops to observed flame volume, so as to render substantially impossible precise periodic interruption of atomic production of interest in the flame. Accordingly, the application precise of modulation of the atomic emission radiation from the flame, so as to facilitate electronic separation of the output signal of interest from interferences in the nature of flame radiation output signals and the like, is complicated.

k. Highly accurate, simultaneous multielement analysis of the same sample by atomic emission spectroscopy is not truly achievable with the pneumatic nebulizer burner and like apparatus of the prior art, which is due, in large measure, to the inapplicability of precise modulation techniques thereto.

OBJECTS OF THE INVENTION It is, accordingly, an object of this invention to provide new and improved method and apparatus for highly accurate sample analysis by atomic spectroscopy.

Another ogject of this invention is the provision of method and apparatus, as above, which provide for sample drops of substantially uniform size and the formation of the sample element atoms of interest in highly concentrated manner in a relatively small sample volume or atom cloud in the sample burner flame and which may readily be observed by appropriate detector means with significant increase in analysis appa ratus sensitivity and accuracy of the analysis results.

Another object of this invention is the provision of method and apparatus, as above, which function to significantly reduce sample and flame fuel gas consumption.

Another object of this invention is the provision of method and apparatus, as above, of significantly increased reliability in that the problems of sample burner clogging and/or flashback are substantially eliminated.

Another object of this invention is the provision of method and apparatus, as above, which provide for significant increase in sample burner flame stability and sample burner flame temperature stability.

Another object of this invention is the provision of method and apparatus, as above, which provide for an increased residence time of the sample drops in the burner flame to increase apparatus sensitivity.

Another object of this invention is to provision of method and apparatus, as above, which significantly reduce radiation signal inaccuracies as caused by chemical interference and light scattering, and the like.

A further object of this invention is the provision of method and apparatus, as above, which enable precise and accurate modulation of the sample drop supply to the observed sample volume or atom cloud, so as to provide for precise modulation of the detector means output signals and resultant simplification of the output signals processing means.

A further object of this invention is the provision of method and apparatus, as above which enable precise and highly accurate simultaneous multielement sample analysis by atomic fluorescence spectroscopy and/or atomic emission spectroscopy.

A still further object of this invention is the provision of method and apparatus, as above which are particularly, though not exclusively, adapted for use in the automated analysis by atomic spectroscopy of a series of blood serum samples.

SUMMARY OF THE INVENTION As disclosed herein, the new and improved method and apparatus for the analysis of samples by atomic emission spectroscopy and/or atomic fluorescence spectroscopy comprise significantly improved atom production means for achieving the requisite production of the atoms of the sample element or elements of interest. These atom production means take the form of a burner body having a generally central sample drop passage extending generally longitudinally thereof. Drop generator means are operatively associated with said burner body at the lower extremity thereof and are effective to generate a stream of drops of substantially uniform size for upward travel through said burner body passage into the burner flame, so as to provide a concentrated atom cloud or sample volume at an advantageous, relatively low location in said burner flame.

Wide aperture detector means are provided and focused substantially only on said atom cloud or sample volume, with the result that substantially only the relevant radiation of interest from said atom cloud impinges upon said detector means, so as to provide a highly accurate analysis output signal.

In other disclosed forms, said improved means for producing atoms of the sample element or elements of interest comprise flameless sample heating means which are used in conjunction with a body member of the same general form as said burner body. The flameless sample heating means take the form of suitable heating means, or a suitable plasma discharge heating means, each of which is effective to heat the sample drops upon the passage thereof through the body member aperture to a sufficient degree to effect the requisite atom production of the sample element or elements of interest.

Means to effect the precise modulation of the sample element atom production in the observed sample volume or atom cloud, with attendant precise modulation of the output signal provided from the apparatus detector means, are provided and take the form of a variety of electrical means in the nature of sample drop charging and deflecting electrodes or the like which are operable to periodically and precisely deflect the sample drop stream from passage into and out of said atom cloud or sample volume, so as to effect the desired modulation of sample element atom production.

Means are provided to enable the simultaneous multielement sample analysis by atomic fluorescence spectroscopy and/or atomic emission spectroscopy of elements present in two different solutions and comprise a plurality of drop generator means positioned relative to said burner body, or like member for directing a plurality of drop streams, respectively, through the relevant sample drop passage, and for modulating said drop streams or periodic alternating interrupting said drop streams in prearranged sequence, so as to enable simultaneous multielement sample analysis substantially without radiation interference. In this form of the invention, the modulation means take the form of pulse modulated signal generator means which are operative to modulate both the sample element atom production in the sample volume or atom cloud for modulation of the atomic emission radiation, and to modulate the light sources for modulation of the atomic fluoroscent radiation. A representative application of the method and apparatus of the invention for use in automated, blood serum sample supply, treatment and analysis means for blood serum metal salt determination by atomic emission spectroscopy -and/or atomic fluorescence spectroscopy is also disclosed.

DESCRIPTION OF THE DRAWINGS The above and other objects and advantages of this invention are believed made clear by the following detailed description thereof taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a partially schematic, longitudinal crosssectional view of apparatus for sample analysis by atomic spectroscopy constructed and operative in accordance with the teachings of this invention;

FIG. 2 is a top view of the sample burner and light source means of the apparatus of FIG. 1 taken generally along line 2-2 in the latter;

FIG. 3 is a partially schematic, longitudinal crosssectional view taken through another form of the apparatus of FIG. 1;

FIG. 4 is a partially schematic, longitudinal crosssectional view taken through another form of the apparatus of FIG. 1;

FIG. 5 is a partially schematic, longitudinal crosssectional view taken through another form of the apparatus of FIG. 1;

FIG. 6 is a partially schematic, longitudinal crosssectional view taken through apparatus for the simultaneous, multielement sample analysis by atomic absorption and/or atomic emission spectroscopy;

FIG. 7 is a plan view of the filter wheel of the apparatus of FIG. 6;

FIG. 8 is a partially schematic, longitudinal crosssectional view taken through apparatus for atomic spectroscopic sample analysis wherein provision is made for modulation of the provided radiation signal;

FIG. 9 is a partially schematic, longitudinal crossscctional view taken through apparatus for simultaneous multielement sample analysis by atomic fluorescence and/or atomic emission spectroscopy;

FIG. 10 is a partially schematic, longitudinal crosssectional view taken through another form of apparatus for simultaneous multielement sample analysis by atomic fluorescence and/or atomic emission spectros- FIG. 11 is a partially schematic, longitudinal crosssectional view taken through apparatus for simultaneous multielement analysis by atomic fluorescence spectroscopy including means to precisely pulse modulate the radiation signals;

FIG. 12 is a plan view of the filter wheel of the apparatus of FIG. 11;

FIG. 13 is a graph of the pulse modulated signal train utilized in the operation of the apparatus of FIG. 12;

FIG. 14 is a partially schematic, longitudinal crosssectional view taken through apparatus for simultaneous multi-element sample analysis by atomic emission spectroscopy and atomic fluorescence spectroscopy; and

FIG. 15 is a schematic diagram illustrating a representative application of the method and apparatus of the invention for use in automated blood sample analysis apparatus.

DETAILED DESCRIPTION OF THE INVENTION Referringnow to FIG. 1, apparatus constructed and operative in accordance with the teachings of this invention for the analysis of a liquid sample by atomic emission and/or atomic fluorescence spectroscopy are indicated generally at and comprise sample supply means 21, drop generator means 22, sample burner means 24, light source means 26 and detector means 28.

The sample supply means 21 comprise a liquid pump 30 which may, for example, take the general form of that shown in US. Pat. No. 3,227,091 issued Jan. 4, 1966 to Jack Isreeli, and includes an inlet conduit 32 which extends as shown into a suitable container 33 of the liquid sample 34 of interest, and a pump outlet conduit 36.

The drop generator means 22 comprise a capillary tube 38 which connects with the pump outlet conduit 36 and includes a very small diameter sample exit hole 40 formed adjacent the extremity thereof. A very fine filter is indicated schematically at 42 and is interposed in the pump outlet conduit 36 to prevent impurities in the liquid sample 34 from clogging the capillary tube 38 and/or the exit hole 40.

Means to vibrate the capillary tube 38 at an appropriate frequency are indicated generally at 43, and, as depicted in FIG. 1, comprise a transducer 44 taking the form of a PZT bimorph transducer 44 which is in physical contact with the end portion of capillary tube 38 transducer 44 is vibrated at an appropriate frequency by a periodic voltage applied thereto by oscillator and power amplifier means 46 and 48,. respectively, and in turn vibrates the capillary tube portion 38 generally longitudinally thereof as indicated by the arrow drawn adjacent thereto. Alternatively, the vibratory means 43 may take the form of a mechanical mechanism in the natureof a motor drive cam which is effective to vibrate the capillary tube 38, as described. As a further alternative, it may be understood that the sample exit hole 40 may be formed adjacent the end of the capillary tube and the latter vibrated generally transversely. A still further arrangement might comprise the use of the vibratory means 43 to actuate a mechanical chopping device which was effective to periodically interrupt the flow of liquid sample to and through the capillary tub 38.

With the respective sample supply means 21 and drop generator means 22 arranged as described, concomitant operation of the pump means 30 and transducer 44 will be effective to pump a thin stream of the liquid sample 34 through the capillary exit hole 40 and to break up said stream into sample drops, as indicated at 49, of substantially uniform size and spacing.

Referring now to the sample burner means 24, the same may comprise a burner body 50 having a generally cylindrical, sample drop chamber 52 extending generally centrally thereof. For use as described in detail hereinbelow, it may be understood that the burner body 50 and capillary tube 38 are relatively arranged so that the axis of the sample drop chamber 52 is sub stantially coincident with the axis of the sample exit hole 40, whereby the stream of sample drops 49 will travel through said sample drop chamber, as depicted. Further, burner body 50 includes are a plurality of spaced relatively small diameter fuel-air mixture chambers 54, and a fuel-air mixture supply conduit 56 in fluid-flow communication therewith to provide a burner flame 58. With the respective burner means 24 and drop generator means 22 arranged, as described, the respective sample drops 49 will travel upwardly, as shown, through the sample drop chamber 52 into the burner flame 58.

For use in the conversion of metal salt molecules to atoms for atomic emission or fluorescence spectroscopy, the longitudinal extent of the burner body 50 and the sample drop chamber 52 are preferably made as large as is commensurate with effective drop generator and burner means function to thereby provide for maximum practicable sample drop transit time through said sample drop chamber. In addition, the respective fuelair mixture chambers 54 may be understood to be made as numerous and small as practicable to inhibit burner flame flashback.

The light source means 26 comprises a lamp 60 which may, for example, take the form of a hollow cathode lamp energized from a suitable power supply 62, and is effective to irradiate the flame 58 with radiation of a wavelength appropriate to the performance of atomic fluorescence spectroscopy with regard to a constituent of interest of the liquid sample 34. The light source means 26 are disposed, as shown, at a substantially 90 angle relative to the detector means 28 to prevent the undesirable direct incidence of radiation from the former on the latter.

The detector means 28 comprises wide aperture optical means, taking the form of a very large aperture lens or equivalent mirror 64, an exit pupil 66, a filter 68 of appropriate bandpass, a suitable photoelectric device 70, and signal processing circuitry and read-out means 72 to process the output signals from the photoelectric device 70 and provide appropriate indicia of the quantitative sample constituent analysis or analyses of interest.

For use, for example, in the quantitative analysis of a blood serum sample with regard to a metal salt constituent thereof in the nature of calcium or potassium through atomic emission spectroscopy, capillary exit hole 40 might have a diameter of about 0.001 inches, oscillator 46 might have a frequency of 20 KHZ, power amplifier 48 might provide 100V pp, and pump 30 might provide approximately 30 psi of sample pressure to the capillary 38, respectively, to result in the provision of approximately 20,000 sample drops per second, each having an initial velocity of about meters per second and an initial diameter of about 5 0 M. In addition, acetylene might be used to fuel the burner means 50 to result in a burner flame 58 at about 2200C with resultant temperature in the cylindrical sample drop chamber ranging from about 500-l000C.

In operation, as each of the sample drops 49 passes from the drop generator 22 into and through the relatively long sample drop chamber 52 without contact with the walls of the latter, the 500l000C temperature prevailing in the latter will be effective to reduce sample drop size, as illustrated, to a very significant extent through partial desolvation or solvent vaporization prior to the reaching of the burner flame 58 by said sample drops. As a result, the conversion to atoms of the metal salt molecules of the sample constituent of interest in the thusly reduced sample drops 49 will occur more quickly relatively low in the flame 58, where conditions are most suitable for atom production, so as to result in the formation of a reasonably well defined or concentrated metal salt atom cloud or sample volume 74. The detector means 28 are, of course, substantially focused only on the atom cloud 74 to detect radiation therefrom and provide indicia of the concentration of the metal salt sample constituent of interest to the read-out means 72.

For use in metal salt sample constituent quantitative analysis by atomic fluorescence spectroscopy, rather than atomic emission spectroscopy, the operation of apparatus 20 would be substantially, as described, with the hollow cathode lamp 60 being effective to provide radiation of the appropriate wavelength to effect the requisite irradiation of the atom cloud 74 of the burner flame 58.

Apparatus 20 will provide sample drops 49 of substantially uniform size within a standard deviation, for example, of $0.05 percent, and this feature, taken in conjunction with a sample metal atoms concentration in the atom cloud 74 of approximately seventeen times that of a conventional burner, and an approximately 5 meter per second sample drop entrance velocity into the burner flame 58as compared to a conventional burner sample entrance velocity of 10 or more meters per second-with attendant significant increase in sample residence time within said flame, provide a significant increase in apparatus sensitivity as expressed in terms of the concentration of the metal salt of interest. Too, the rate of sample consumption will be reduced from the approximately 2 ml per minute required by conventional burners to approximately 0.05 ml per minute, so as to increase absolute sensitivity expressed as total weight of the metal salt of interest since much less sample is needed, and increase burner flame stability since less sample evaporization induced burner flame turbulence will occur.

In addition, the provision of the relatively concentrated atom cloud 74 at a relatively low point in the burner flame 58, where solvent evaporation and metal salt molecule dissolution to atoms is substantially complete, will inhibit light scattering and minimize chemical interferences, both with attendant increase in the operational accuracy of the detector means 28. The fact that the sample drops do not reach the outer oxidizing zone of the burner flame 58 while at the depicted atom cloud height for viewing by the detector means 28 will minimize oxide particle formation and selfabsorption of the radiation of interest. Also, the focusing of the detector means 28 substaritially only on the atom cloud 74 will, of course, increase the accuracy and sensitivity of said detector means, since substantially only the relevant radiation from said atom cloud will be applied to the photosensitive detector 70.

Further, the introduction of the sample 34 through the sample drop chamber 52 in the burner body 50 will prevent burner clogging by solids in said sample, or sample deposition, since the sample is no longer required to pass through very small and highly heated holes in said burner body, and allows the utilization of a burner body 50, as depicted, with many small diameter fuel-air supply chambers 54 with attendant prevention of flashback.

Too, since the pneumatic sample nebulization function of conventional burners, with attendant high fuel exit velocities from the burner, is not required by the burner means 24 of the invention, it may be understood that lower fuel exit velocities, with attendant smaller burner flame 58 and longer fuel residence time in said burner flame, may be employed to thus reduce burner fuel consumption and cost.

In the form of the invention as indicated at in FIG. 3, the burner means 24 are replaced as shown by flameless sample heating means 82, which comprises a cylindrical member 84 having a sample drop chamber 86 extending therethrough as shown. A heating coil or similar heating element is indicated at 88 and surrounds the member 84, as shown. In operation, the heating coil is energized to heat the chamber 86 to a molecule-toatom conversion temperature of 2500C to 3000C, while the drop generator means 22 are operated to generate and direct the stream of sample drops 49 through said heated chamber, with resultant desolvation and partial conversion of the metal salt molecules of inter est to atoms. Some of these atoms persist beyond the chamber 86 to result in the formation of the atom cloud 74 with attendant performance of the spectroscopic measurement process by the detector means 28. As discussed hereinabove with regard to the longitudinal extent of the sample drop chamber 52 of the burner body 50 (FIG. 1), it may be understood that the longitudinal extent of the sample drop chamber 86 is also made as large as is practicable to result in maximum practicable molecule-to-atom conversion within said chamber.

Flameless heating means other than the heating coil 88 or the like may alternatively be employed to provide the requisite molecule-to-atom conversion temperature within the sample drop chamber 86. More specifically, and as seen in the apparatus 89 of FIG. 4, said other flameless heating means may take the form .of plasma discharge means 90 which are disposed, as shown, within the chamber 86. The plasma discharge means 90 comprises spaced

electrodes

92 and 94 which are energized from

lines

96 and 98 to maintain a plasma discharge, as indicated by dashed lines 100, therebetween and provide the requisite molecule-to-atom conversion temperature within said chamber. Alternatively, said plasma discharge may be maintained in said chamber by radiofrequency excitation. Too, a non-illustrated ion source may, if desired, be operatively disposed within the sample drop chamber 86 to facilitate the striking of the plasma discharge 100.

In use, the sample drops 49 are again projected as shown from the drop generator means to and through the plasma discharge 100 in the chamber 86 with resultant partial conversion to atoms of the metal salt molecules of interest and persistence of some of these atoms beyond the flameless heating element 82 to form the atom cloud 74 for spectroscopic measurement as above.

FIG. depicts the apparatus 89 of FIG. 4 further including gas supply means to maintain the plasma discharge 100 and substantially prevent sample oxidation at the high prevailing temperature by oxygen in the surrounding atmosphere. More specifically, said gas supply means, indicated generally at 102, comprises an annular member or annulus 104 which is disposed, as shown, intermediate the drop generator means 22 and plasma discharge 100 and surrounds the path of the sample drops 49.

A rare or inert gas in the nature of Ar, CO or N is supplied as indicated by conduit 102to the member 104, and the latter comprises a generally annular gas discharge opening 108 formed as shown at the top thereof and through which said rare or inert gas is discharged to form a generally annular stream 110 which flows, as indicated, to surround the ascending sample drops 49 and the atom cloud 74. Thus, gas to maintain the plasma discharge 100 is provided, while oxidation of the sample is substantially prevented. If desired or deemed necessary, the rare or inert gas supply means 102 of FIG. 5 may, of course, be incorporated in the apparatus 80 of FIG. 3 to substantially prevent sample oxidation, as described.

Solvent extraction and/or other separation techniques such as the use of liquid resins are particularly useful techniques for use in atomic spectroscopy analysis for increasing sensitivity and removing interferents, so as to increase accuracy. In certain cases, it becomes desirable to analyze a sample for several elements, some of which are readily extractable into an organic phase of liquid resin while others remain in the aqueous phase. Through use of automatic multielemnt atomic emission and/or atomic fluorescence spectroscopy, it becomes possible to simultaneously analyze elements present in both phases of a sample to significant advantage.

Apparatus for simultaneous multielement analysis in which the elements or blood sample constituents of interest are present, for example, in two phases as a result of solvent extraction, as discussed above, are indicated generally at 112 in FIG. 6 and comprises burner means 24 of the apparatus 20 of FIG. 1 having first and second drop generator means 22A and 22B operatively associated therewith, as shown. The drop generator means are effective to simultaneously project a first stream of sample drops 49A from the sample in phase A and a second stream of sample drops 49B from the sample in phase B, respectively, through the sample drop chamber 52 into the burner flame 58 for partial conversion to atoms, as described, at the sample volume or atom cloud here indicated at 74AB.

The detector means 28 here comprises a rotatable filter wheel 114 having

filters

68A and 68B disposed thereon, as illustrated in FIG. 7, and having bandpass characteristics which are respectively appropriate to spectroscopic analysis for first and! second sample constituents of interest.

Filters

68A and 68B are operatively positioned in turn, in front of the photoelectric device upon rotation of the filter wheel 114 in any suitable manner as, for example, through use of a nonillustrated electric drive motor.

The light source means 26 would, in this instance, comprise sequentially energizable lamps 60A and 6013 powered from power supply 62. Switching means, indicated at 116, are provided and operatively associated, as indicated by the dashed lines, with the rotatable filter wheel 114 and the lamp power supply 62 to effect the sequential energization of the respective lamps 60A and 608 in accordance with the respective dispositions of the filters 68A and 683 relative to the photoelectric device 70, in the manner described] in further detail, for example, in my copending application for US. patent, Ser. No. 827,554, filed May 26, 1969, and assigned to the assignee hereof. Lamp 60A is operative to emit radiation appropriate to the atomic fluorescence analysis of the sample volume or atom cloud 74AB for one sample constituent or element, and the bandpass of filter 68A is appropriate to pass substantially only radiation of such wavelength. In like manner, lamp 683 is operative to emit radiation of a wavelength appropriate to the analysis of the atom cloud 74AB for a different sample constituent or element of interest, while the bandpass of filter 68B appropriate to pass substantially only radiation of that wavelength.

For use of the apparatus 112 for the simultaneous multielement analysis by atomic fluorescence spectroscopy of a sample which has been separated by solvent extraction into an organic phase and an aqueous phase, one of said phases would be supplied as indicated in FIG. 6 to the drop generator means 22A, while the other of said sample phases would be supplied to the drop generator means 228, whereby simultaneously operation of said drop generator means, with concomitant sequential energization of the

lamps

60A and 60B and appropriately phased rotation of the filter wheel 114, will be effectvie to accomplish the desired sample analysis, as discussed above.

Simultaneous multielement analysis by atomic emission spectroscopy of a sample through use of the apparatus 112 may, of course, be readily effected through the simple expedient of not energizing either of the

lamps

60A and 60B. Alternatively, simultaneous multielement analysis of a sample by atomic emission spectroscopy for one sample constituent and by atomic fluorescence spectroscopy for another sample constituent through use of the apparatus 112 may be readily effected through the periodic energization of one of said lamps, only.

Apparatus for periodically producing sample constituent atoms of interest in the sample volume or atom cloud 74 for the analysis of a liquid sample by atomic emission and/r atomic fluorescence spectroscopy are indicated generally at 1 17 in FIG. 8 and comprises sample supply means 21, drop generator means 22, sample burner means 24, light source means 26 and detector means 28, operatively arranged as described. In addition, the apparatus 117 comprises a cylindrical charging electrode 118 energized, as indicated, from line 1 l9 and having a passage 120 extending therethrough in substantial alignment with the sample drop passage 52 in the burner body 24, and a part of deflecting

electrodes

122 and 124 disposed at either side of said sample drop path and energized, as indicated, from

lines

126 and 128.. V I V In use of the apparatus 117, the application of a voltage, for example, +350V to the charging electrode 118 will induce a charge on the sample drops 49 passing therethrough, whereby the concomitant application of a deflecting voltage, indicated by the curve 130, which varies, for example, between +3KV and 3KV across the deflecting

electrodes

122 and 124 will periodically deflect said sample drops substantially along the path indicated by the dashed line 121 out of the sample volume or atom cloud 74 to thus prevent detection of the radiation therefrom by the photoelectric device 70. Accordingly, it may be understood that the sample constituent radiation of interest which impinges upon the detector means 28 will, in effect, be modulated, as indicated by the output signal curve 132, in accordance with the rate of variation of the deflecting voltage 130 applied across the deflecting

electrodes

122 and 124. The output signal from the photoelectric device 70 of the detector means 28 is thusly converted to an AC sig nal to avoid the necessity for relatively expensive DC amplifiers in the detector means 28 as should be obvious. Too, the modulation of said output signal will advantageously provide for significant increase in background noise rejection to again improve apparatus accuracy and sensitivity.

For operation in a somewhat different manner but with substantially the same advantageous results, the capillary tube of the drop generator means 22 and the charging electrode 118 may be maintained as a constant potential difference, and a periodic voltage varying between zero and a suitable value applied to the

respective deflecting electrodes

122 and 124 concomitant with the passage of the sample drops 49 therethrough to periodically deflect the latter as described. More specifically, when this periodic voltage is zero, said sample drops will be substantially undeflected and follow the normal path thereof to the sample volume or atom cloud 74 for partial conversion to atoms, as described. Alternatively, when said periodic voltage is of sufficient magnitude, said sample drops will be deflected, again along the dashed line path 121 as shown, to thus avoid passage through said atom cloud with attendant avoidance of the detection of the radiation therefrom by the photoelectric device of the detecting means 28.

Use of the apparatus 117 for sample analysis by atomic fluorescence spectroscopy would, of course, include the energization of the lamp 64, while use of said apparatus for sample analysis by atomic emission spectroscopy would not include such lamp energization.

The above described methods and apparatus for the periodic production of sample constituent or element atoms in the sample volume or atom cloud 74 are each effective to provide for substantially precise control over the trajectory of the sample drops 49 with attendant substantially precise modulation of the atomic emission and/or fluorescence signals of interest. In addition, since the size of the stream of sample drops 49 is very small relative to the size of the burner flame 48, it may be understood that sample drop deflection will not result in significant distrubance of said burner flame.

Apparatus for the simultaneous analysis of high and low concentration sample elements or constituents are indicated generally at 142 in FIG. 9 and, in the manner of the apparatus 112 of FIG. 6, comprise first and second drop generator means 22A and 22B operatively associated with the burner body 24. In addition, and in the manner of the apparatus 117 of FIG. 8, the apparatus 142 of FIG. 9 may comprise a cylindrical charging electrode 118A and deflecting

plates

122A and 124A operatively associated with the drop generator means 22A, and a cylindrical charging electrode 1 18B and deflecting plates 1228 and 1248 operatively associated with the drop generator means 22B. These operatively associated charging electrodes and deflecting plates are operable in the manner described hereinabove with regard to the apparatus 117 of FIG. 8. More specifically, with the charging electrode 118A and deflecting

plates

122A and 124A energized, as described, the sample drop stream 49A from drop generator means 22A will be deflected along the path, as indicated by the dashed line 121A, and not enter the sample volume 74AB. In like manner, with the charging electrode 118B and deflecting plates 1228 and 124B energized, as described, the sample drop stream 49B from drop generator means 228 will be deflected along the path, as indicated by the dashed line 1213, and not enter the sample volume 74AB.

For use in simultaneous multielement analysis by atomic fluorescence spectroscopy, the apparatus 142 will include light source means 26 which comprises first and

second lamps

60A and 60B of different emitted radiation wave lengths, and detector means 28 which comprises a rotating filter wheel 114 and lamp switching means 116 operatively associated therewith, as shown, all as described in detail hereinabove with regard to the apparatus 112 of FIGS. 6 and 7.

A typical application of the apparatus 142 might comprise the analysis, by simultaneous multielement atomic fluorescence spectroscopy, of a blood serum sample for each of the sodium and iron constituents thereof. Since, in a typical serum sample, the sodium constituent may occur in a concentration, for example, of 3,000 ppm, while the iron constituent may occur in a concentration, for example, of only 1 ppm, the simultaneous spectroscopic analysis thereof by conventional pneumatic nebulizer techniques and the like, or by any technique which requires simultaneous sodium and iron atom conversion and excited fluorescent radiation from the atom cloud 74AB, would prove estremely difficult, if not impossible. As a result, a part of the serum sample may be diluted, for example, 3,000 times and fed, as indicated, to the drop generator means 22A for use in the sodium determination, while the original undiluted part of the serum sample is fed, as indicated, to drop generator means 22B for use in the iron determination.

In operation, for such use, the respective operatively associated charging electrodes and deflecting plates are alternately and sequentially energized in synchronism with the sequential energization of the

respective lamps

60A and 60B and in synchronism with the periodic rotation of the filter wheel 114, so as .to alternately deflect the respective

sample drop streams

49A and 49B out the sample volume 74AB.

Thus, for example, with only the charging electrode 118 3 and the deflecting plates l2 2B and 1248 energized, the stream of drops 4913 from drop generator means 22B may be deflected, as shown, along path 1218, so as not to enter thesample volume or atome cloud 74AB, while the undeflected stream of drops from the drop generator means 22A would pass through the burner flame into the atom cloud 74AB for partial conversion of the sodium atoms, as described. As this occurs, lamp 60A would be energized to provide appropriate sample volutne irradiation sodium atom fluorescence, while filter wheel 1 14would be arranged so that filter 68A is operatively positioned relative to the photosensitive device 7 to provide for appropriate detection of the sodium atom fluorescent radiation.

Alternatively, with only the charging electrode 118A and deflecting

plates

122A and 124A energized, sample drops 49A would be deflected along the path 121A, so as not to pass int o the atom cloud 74AB, while the undeflected sample drops 49B would pass into said atom cloud for partial conversion of the iron atoms, as described. As the latter occurs, lamp 608 would, of course, be energized to provide appropriate radiation for iron atom fluorescence, while filter wheel 114 would be rotated through approximately 180 to operatively position filter 68 B relative to the photosensitive device 70 to thus provide for appropriate detection of the iron atom, fluorescent radiation. Operation of the apparatus 142 would, of course, be continuous, as described, with intermittent passage of the sample drops 49A and 49B, and intermittent energization of the

lamps

60A and 60B and rotation of the filter wheel 114 functioning to provide for accurate, simultaneous atomic fluorescence spectroscopic analysis of the sample for both the sodium and iron constituents thereof.

Use of the apparatus 142 for simultaneous multielement sample analysis by atomic emission spectroscopy may, of course, be readily effected through the simple expedient of failing to energize the

respective lamps

60A and 60B attendant such analysis. Alternatively,

the said lamps, and the power supply 62 and switching device 116 may, of course, be eliminated altogether.

Another form of apparatus for the simultaneous analysis of high and low concentration sample elements or constituents is indicated generally at in FIG. 10. In the apparatus 150, quick-acting flow interrupting means which may, for example, take the form of valve means as indicated at 152 and 154 are respectively operatively disposed as shown in the sample supply conduits 36A and 36B upstream of the respective capillary tubes 38A and 38B. Said valve means may take any suitable form in the nature, for example, of quickacting solenoid operated valve means, or quick-acting cam operated valve means which are, in any event, effective to intermittently interrupt the flow of sample streams to the respective capillary tubes and thus interrupt the formation of the respective

sample drop streams

49A and 49B from the respective drop generator means 22A and 22 B. In the event that the sample supply pump means (see pump 30 in FIG. 1) are positive acting type pump means, sample return conduits would, of course, be provided as indicated at 153 and 155.

With the valve means 152 open to permit the formation of the sample drop stream 49A, and the valve means 154 closed to prevent the formation of the sample drop stream 498, pass only the former sample drop stream will pass into the atom cloud 74AB for partial sodium atom conversion and atomic fluorescence spectroscopic analysis thereof. Alternatively, with the valve means 152 closed and the valve means 154 open, only drop generator means 228 will be effective to provide the sample drop stream 49B for passage into said atom cloud with resultant atomic fluorescence spectroscopic analysis for iron. In use, the respective valve means 152 and 154 are, of course, operated in any convenient manner in synchronism with the

respective lamps

60A and 60B and the rotation of the filter wheel 114 to again effect, simultaneous multielement atomic fluorescence spectroscopy.

Use of the apparatus 150 for simultaneous multielement sample analysis by atomic emission spectroscopy to, for example, eliminate the problem of radiation interference as might otherwise occur, may be effected through the simple failure to energize or elimination of the

respective lamps

60A and 60B and associated apparatus components.

Apparatus for simultaneous multielement sample analysis by atomic emission spectroscopy and atomic fluorescence spectroscopy are indicated generally at 158 in FIG. 11 and, as depicted therein, may comprise drop generator means 22, sample burner means 24, a charging electrode 118, deflecting

electrodes

122 and 124, which are respectively constructed and operative as described hereinabove with regard to the apparatus 117 of FIG. 8, and light source means 26 and detector means 28, which are respectively constructed and operative in a manner generally similar to that described hereinabove with regard to the

apparatus

142 and 150 of FIGS. 9 and 10. For use in the apparatus, the detector means 28 include a filter wheel 160 which comprises four

filters

68A, 68B, 68C and 68D disposed thereon at generally 90 intervals, as illustrated in FIG. 12. Pulse modulated generator means 162 are provided and are operatively connected, as indicated, to the deflecting electrode 122 and the light source 26. The pulse modulated signal generator means 162'are operative to repetitively generate a series or train of pulse modulated signals as'indicated at S1, S2, S3 and S4 in the graph 162 of FIG. 13.

For use of the apparatus 158 in the simultaneous multielement analysis of, for example, a blood serum sample which contain elements or constituents of interest A and B which are best analyzed for by atomic fluorescence spectroscopy, and elements or constituents C and D of interest which are best analyzed for by atomic emission spectroscopy, lamp 60A would be effective to emit radiation of appropriate wave length for fluorescence of the atoms of element A in the sample volume or atom cloud, indicated at 74ABCD, lamp 608 would be effective to emit radiation of appropriate wave length for the fluorescence in said atom cloud of the atoms of element B, filters 68A and 688 would be of bandpasses which are respectively appropriate to the passage of the atomic fluorescence radiation for elements A and B to the photosensitive device 70, while filters 60C and 60D would be of bandpasses which are respectively appropriate to the passage of the atomic emission radiation of elements C and D to said photosensitive device.

In operation, the sample drop stream 49ABCD would be continuously passed to the sample volume or atom cloud 74ABCD for the duration of the pulse modulated signal S1 to provide an approximately constant atomic concentration of element A in said atom cloud. Concomitantly, the signal S1 is applied from the signal generator means 162 to the light source 26 to energize lamp 60A and effect emission therefrom of pulse modulated resonance radiation of element A to irradiate the atom cloud 74ABCD and cause the emission of pulse modulated fluorescent radiation for element A therefrom. At the same point in time, the filter wheel 160 is, of course, rotated to operatively position the filter 68A as shown relative to the photosensitive device 70 of the detector means 28 to thus provide for the appropriate detection of the pulse modulated, fluorescent radiation of interest. At the termination of the pulse modulated signal S1, the filter wheel 160 is again rotated to operatively position filter 60B relative to said photosensitive device. As this occurs, the signal generator 162 will commence the generation of the signal S2 and the application thereof to the light source means 26 with resultant emission by lamp 608 of pulse modulated resonance radiation of element B to again irradiate the atom cloud 74ABCD and effect the emission of pulse modulated fluorescent radiation for element B therefrom for appropriate detection by the detector means 28 as described.

At the termination of signal S2, the filter 160 is rotated to operatively position filter 68C relative to the photosensitive device 70. At this occurs, the signal generator 162 will commence the generation of pulse modulated signal S3 and the application thereof to the deflecting electrode 122 to effect pulse modulation of the drop stream 49ABCD with resultant intermittent deflection of said sample drop stream away from said atom cloud as indicated by the dashed line and attendant pulse modulation of the atomic emission radiation of element C as detected by the detector means 28.

At the termination of the pulse modulated signal S3, the filter wheel 160 will again be rotated to operatively position filter 68D relative to the photosensitive device 70. Following this, the signal generator 162 will commence the generation of the pulse modulated signal S4 and the application thereof to the deflecting electrode 122 with resultant pulse modulation of the atomic emission radiation from the atom cloud 74ABCD for element D. No energization of the light source means 26 is effected during the generation of the pulse modulated signals S3 and S4 by the signal generator means 162.

As a result of the above, it is believed clear that the photosensitive device of the detector means 28 will receive a sequence of signals as caused by the fluorescent excited radiation for elements A and B, and the thermally excited radiation for elements C and D, respectively, with each of said signals being pulse modulated at the same frequency to pulse modulate accordingly the electrical output signal provided by said photosensitive device and greatly facilitate the processing and accurate readout thereof by the readout means 72 'in the manner disclosed, for example, in my said copending application for US. Pat. Ser. No. 827,554.

Certain sample elements or constituents, particularly those which emit radiation at low ultraviolet wave lengths, provide atomic emission radiation of relatively low intensity with attendant relatively low, and generally unacceptable, signal-noise ratios. For the simultaneous multielement analysis ofa sample containing one such element by atomic emission spectroscopy and atomic fluorescence spectroscopy, it may be understood that the atomic emission spectroscopy signalnoise ratio of interest may be significantly increased by irradiation of the sample volume or atom cloud with resonance radiation of the element in question which emits radiation in said low ultraviolet wave lengths. Apparatus to accomplish this function are indicated generally at 164 in FIG. 14 and may be seen to comprise the drop generator means 22, burner body means 24, charging electrode 118, and deflecting

electrodes

122 and 124, constructed and operative as described hereinabove with regard to the apparatus 117 of FIG. 6. Further included are a light source 26 comprising a single lamp 608 which is effective to ,emit resonance radiation of the law wave length radiation element in question, and detector means 28 constructed and operative as described with regard to the apparatus 112 of FIGS. 7 and 8.

For use of the apparatus 164 for the simultaneous multielement analysis of a sample by atomic emission spectroscopy for element A and atomic fluorescence spectroscopy for element B, a continuous sample drop stream 49 would be provided to the atom cloud 74AB for the element A analysis time period. As this occurs, thermally excited radiation for element A, which element may be understood to provide an adequate signalnoise ratio, will be provided for detection by the detector means 28 with filter 68A operatively positioned, as shown, relative to the photosensitive device 70. Accordingly, no irradiation of the atom cloud 78AB will be required during this sample element analysis time period. As this sample element analysis time period terminates, the filter wheel 114 will be rotated to operatively position filter 688 relative to the photosensitive device 70, while the light source 608 is energized to irradiate the sample cloud 74AB with constant intensity resonance radiation of element B which element does not, as set forth hereinabove, provide an adequate signal noise ratio with thermal emission alone. Concomitantly, the sample drop stream 49AB is modulated, as described hereinabove with regard to the apparatus 117 of FIG. 6, by the application of an appropriate periodic voltage between the deflecting

electrodes

122 and 124, whereby the combined signals arriving from the thermally excited radiation from the atoms of element B may be detected as described by the detector means 28 with a satisfactory signal-noise ratio. Alternatively, the analysis for element B may be effected by introducing a constant drop stream 49AB into the atom cloud 74AB and irradiating said atom cloud during the element B analysis time period by the pulse modulation of the constant intensity resonance radiation from lamp 603 as described hereinabove with regard to the apparatus 158 of FIG. 11.

FIG. illustrates a representative application of the new and improved atomic spectroscopy sample analysis method and apparatus of the invention to the automated atomic spectroscopic analysis of a series of blood serum samples for operation in conjunction with the automated colorimetric analysis thereof.

More specifically, apparatus for the automated, sequential supply, treatment and colorimetric and spectroscopic analysis of a plurality of blood serum samples with regard to a plurality of constituents of interest of each of said samples are indicated generally at 170 and may be understood to take the general form of those shown and described, for example in U.S. Pat. No. 3,134,263 issued May 26, 1964 to Edward B.M. De- Jong. The apparatus 170 comprise a turntable 172 upon which is disposed a generally circular array of blood serum containers 174. A sample off-take device is indicated at 176 and comprises a sample off-take probe 178 and probe operating means 180, respectively. A wash liquid receptacle 182 is disposed as shown adjacent the turntable 172, while drive means are indicated at 176 and are operatively connected as indicated by the dashed lines to drive each of the turntable 172 and the sample off-take probe operating means 180.

In operation, the turntable 172 is intermittently rotated, or indexed, to present each of the blood serum sample containers 174 in turn to the sample off-take probe 178, while the latter is in. turn intermittently operated to immerse the inlet end of said probe in a thusly presented sample container for a predetermined period of time to aspirate (as described in detail hereinbelow) a predetermined volume of the blood serum sample therefrom, to then transfer the said off-take probe inlet end through the ambient air for immersion in the wash liquid receptacle 182 for a predetermined period of time to thus aspirate a predetermined volume of ambient air for use as a separating and cleansing fluid, followed by a predetermined volume of said wash liquid therethrough, and to again transfer the said off-take probe inlet end through the ambient air for immersion in the next presented sample container 174 for a predetermined period of time, to thus aspirate another predetermined volume of ambient air therethrough and commence the aspiration of a like, predetermined volume of the blood plasma sample from said next presented sample container.

As a result, it may be understood that a fluid stream consisting of successive, predetermined volumes of said blood serum samples as spaced, in each instance, by a segment of air, a segment of the wash liquid, and a segment of air, respectively, will be supplied to the sample off-take probe 178.

This sample stream is divided as indicated into a plurality of sample portion streams and pumped as indicated by the sample pump 184 to sample portion treat- -ment means 186 for appropriate sample portion treatment to enable subsequent, automated sample portion analysis. Those portions of each of the blood serum samples which are to be colorimetrically analyzed are then supplied, as indicated as suitably phased series streams to colorimetric sample analysis means as indicated at 188, while those portions of each of said blood samples which are to .be analyzed by atomic spectroscopy analysis are supplied, as indicated, as suitably phased series streams, following removal of said air segments from each of said streams by debubbler means 190, to the atomic spectroscopy sample analysis means indicated at 192.

Colorimetric and spectroscopic analysis means output signal processing means which may, for example, include suitable demodulation, calibration and amplitier means and the like, are indicated at 193; while sample analysis results read-out means are indicated at 194 and may, for example, take the form of a null-balance type, DC strip chart recorder which comprises a drive recorder strip chart 196 and a recorder pen or stylus 198 which is operative to trace a graph 200 on said strip chart. Each of the colorimetric sample analysis means 188 and the atomic spectroscopy sample analysis means 192 are, of course, operatively connected to said recorder means to provide the analysis results output signals thereto.

In operation, it may be understood that as each sample portion is supplied to the atomic spectroscopy sample analysis means 192, the same will be formed into a sample drop stream and passed through the burner body for partial conversion to atoms of the sample element or elements of interest, with attendant operation of the spectroscopic analysis means detector means functioning to provide an appropriate output signal for processing by the processing means 193 and operation of the recorder means 194. The colormietric analysis means 188 are, of course, operative in substantially the same manner with the readily apparent exception that the sample portions supplied thereto are, of course, passed through appropriate flow cell means.

Although disclosed hereinabove by way of example as particularly adapted to the quantitative analysis of blood serum samples by atomic spectroscopy with regard to various of the metal salt constituents of said blood serum samples, it is believed clear that the new and improved method and apparatus of the invention would be equally applicable, to like significant advantage, to the analysis by atomic spectroscopy of a wide variety of fluid samples other and different than blood serum samples.

While I have shown and described the preferred embodiment of my invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that certain changes in the form and arrangement of parts and in the specific manner of practicing the invention may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

What is claimed is: V

1. Apparatus for the conversion of a sample to atoms for sample analysis by atomic spectroscopy comprising, body means having an elongated. chamber extending

Claims

1. Apparatus for the conversion of a sample to atoms for sample analysis by atomic spectroscopy comprising, body means having an elongated chamber extending therethrough for passage of said sample through said body means, drop generator means associated with said body means to direct said sample as a stream of successive discrete drops of substantially uniform size for passage of the latter through and axially along said chamber in avoidance of contact with the walls of said chamber, so as to form a relatively concentrated volume of sample atoms without said body means and adjacent one extremity of said chamber, and heating means to heat said sample attendant the passage thereof through said chamber, so as to effect at least partial desolvation of said sample prior to passage of said drops from said chamber and into said concentrated volume, and means independent of and exterior of said chamber for effecting the analysis of said sample atoms in said concentrated volume.

2. In apparatus as in claim 1 wherein, said heating means comprise means to maintain a flame at one extremity of said body means in substantial alignment with said one extremity of said chamber for passage of said sample drops from said chamber into said flame, said maintaining means including air-fuel mixing chamber means independent of said chamber along which said sample drops are passed.

3. In apparatus as in claim 1 wherein, said body means are oriented in generally vertical manner with said chamber extending generally vertically therethrough.

4. In apparatus as in claim 3 wherein, said drop generator means are operably disposed adjacent the other extremity of said body means whereby said sample drop stream will pass generally upwardly from said drop generator means through said chamber.

5. In apparatus as in claim 1 further comprising, means to modulate the concentration of atoms in said sample volume.

6. In apparatus as in claim 5 wherein, said modulation means comprise means to periodically deflect said sample drop stream from passage into said sample volume.

7. In apparatus as in claim 6 wherein, said deflecting means comprise charging electrode and deflecting plate means which are operatively associated with said drop generator means and are respectively operable to charge said sample drops and deflect the same from passage into said sample volume.

8. In apparatus as in claim 1 further comprising, means to direct first and second sample streams of successive discrete drops for passage through said chamber to form a readily observable and relatively concentrated volume of said sample atoms without said body means.

9. In apparatus as in claim 8 wherein, said means to direct first and second sample streams comprise first and second drop generator means which are respectively operatively associated with said body means and are respectively operable to provide first and second sample drop streams for passage through said chamber.

10. In apparatus as in claim 8 further comprising, means to periodically and alternately interrupt the passage of said first and second sample streams to said sample volume.

11. In apparatus as in claim 10 wherein, said drop stream passage interrupting means comprise means to periodically and alternately deflect said first and second drop streams from passage into said sample volume.

12. In apparatus as in claim 11 wherein, said deflecting means comprise charging electrode and deflecting plate means which are operatively associated with said first and second drop generator means and are respectively operable to alternately and periodically charge said samplE drops from said first and second drop streams and deflect the same from passage into said sample volume.

13. In a method for the conversion of a sample to atoms for sample analysis by atomic spectroscopy through the use of body means having an elongated chamber extending therethrough, the steps of, passing a sample through and axially along said chamber as a stream of successive discrete drops of substantially uniform size in avoidance of contact with the walls of said chamber, and heating said sample drops attendant the passage thereof through said chamber to effect at least partial desolvation of said sample drops prior to passage from said chamber, so as to form a readily observable and relatively concentrated volume of sample atoms without said body means and adjacent one extremity of said chamber, and analyzing said sample in said concentrated volume by means independent of and located exteriorly of said chamber.

14. In a method as in claim 13 further comprising, the steps of, modulating the concentration of atoms in said sample volume.

15. In a method as in claim 14 wherein, the modulation of the atom concentration in said sample volume is effected by periodically deflecting of said sample drop stream from passage into said sample volume.

16. In a method as in claim 15 wherein, the step of periodically deflecting said sample drop stream is effected by passing said stream through charging electrode means to charge the same, and subsequently passing said stream through deflecting plate means to deflect the charged sample drop stream from passage into said sample volume.

17. In a method as in claim 13 wherein, the step of passing said sample through said body means chamber comprises passing first and second sample streams therethrough.

18. In a method as in claim 17 wherein, the step of passing said first and second sample streams through said body means chamber is effected by generating first and second sample drop streams adjacent an extremity of said chamber for passage of said drop streams through said chamber to form said sample volume.

19. In a method as in claim 17 further comprising, the steps of, periodically and alternately interrupting the passage of said first and second sample streams to said sample volume.