WO1983003900A1

WO1983003900A1 - Apparatus for use in spectroscopically analyzing properties of test samples

Info

Publication number: WO1983003900A1
Application number: PCT/US1983/000600
Authority: WO
Inventors: Robert J. Cosgrove, Jr.; Victor F. Smolen
Original assignee: Pharmacontrol Corp.
Priority date: 1982-04-23
Filing date: 1983-04-22
Publication date: 1983-11-10
Also published as: EP0106895A1; CA1215248A

Abstract

An apparatus (10) for use in spectroscopically analyzing properties of a plurality of test samples. The apparatus includes a support member (12) for stationarily supporting a plurality of test cells (14) containing test samples (16) to be analyzed and suitable devices for directing a beam of radiation successively at the test cells (14) and for then receiving output radiation from the test cells. The radiation directly (20) and detector devices (30) are mounted in fixed relationship to one another, and arranged with respect to the support member (12) so that when the beam of radiation from the radiation directing device (20) is directed onto one of the test cells (14), the radiation detector (30) will receive output radiation from the same cell. The radiation directing (20) and detector devices (30) are moved as a unit relative to the stationary test cells (14) in a manner so that the beam of radiation from the directing device (20) is directed sucessively at the plurality of test cells (14), whereby the radiation detector device (30) will then receive successively output radiation from the plrality of test cells (14). In this manner, analysis of the properties of a plurality of test samples may be quickly and efficiently made. Further, the fact that the test cells (14) are stationarily supported and the radiation directing (20) and detecting devices (30) are moved relative thereto is most advantageous in connection with spectroscopic analysis of flow through fluid test samples in which the sample fluid to be analyzed is continuously introduced into and withdrawn (17a, 17b) from the stationarily supported test cells.

Description

Apparatus For Use In Spectroscopically Analyzing Properties Of Test Samples

Technical Field The present invention relates to an apparatus for use in connection with spectroscopic analysis of properties of test samples, and more particularly to an apparatus for providing the capability of spectro¬ scopically analyzing a plurality of test samples in a relatively quick and efficient manner. The present invention may be used in connection with many different types of spectroscopic analysis systems, including those for making both quantitative and qualitative analysis of test samples. For example, the apparatus of the present invention may be used in connection with spectroscopic analysis based upon light absorption principles and fluorescence emission principles.

Background Art

Spectroscopic analysis of substances generally involves exposing a test sample or substance to a beam of radiation, and then detecting and analyzing the output radiation from the test sample. The information derived from such analysis may be used for quantitatively and/or qualitatively determining properties of the test sample. For example, spectro¬ scopic analysis may be used in connection with qualitatively determining the concentration of a particular substance in a test solution, such as by determining the drop in intensity of radiation trans- mitted through the test solution. An example of qualitative analysis is the determination of the particular materials or elements contained in the

OMPΪ test solution by virtue of a determination of the_ wavelength of light either absorbed or emitted from the test solution. As is well known, spectroscopic analysis may be based upon either the absorption spectrum, in which the substance is studied by its selective absorption of radiation, or the fluorescence spectrum, in which the substance is studied by the radiation it emits when excited by radition of another frequency. ^" When spectroscopic analysis is to be performed with respect to a large number of samples, such as for example in determining the concentration of substances in various solutions, it is desirable to conduct such spectroscopic analysis as rapidly as possible so that the same basic scanning and detector apparatus may be used in connection with a plurality of.samples. In analyzing multiple samples, most prior art systems employ various means for moving the samples into and out of position for testing with the scanning and detector apparatus. For example, one known prior art system employs a carousel arrangement in which samples are disposed around the carousel and the carousel then rotated on its axis so that he samples pass sequentially between a light source and detector. Other prior art systems involve the movement of test sample in a linear mode between a light source and detector.

Another known technique for spectroscopically analyzing a plurality of test samples has been to provide a stationary test cell or container and then to introduce and withdraw sample solutions therefrom- This technique is particularly useful in connection with spectroscopic analysis of varying or changing test solutions in which it is desired to obtain multiple readings over a period of time. Thus, in

known systems for analyzing a single test solution, a vial or test cell is placed between a scanner and a detector, and the test solution continuously pumped through the test cell. This may be accomplished by connecting inlet and outlet conduits to the test cell. In this manner, repeated analysis may be preferred on the test solution at periodic intervals or even continuously to provide a continuous updating of the properties being analyzed. ' While such known prior art systems for spectroscopically analyzing a plurality of test samples .have proven to be generally satisfactory either with respect to self-contained test samples, or with respect to a single varying or changing test solution, difficulties have arisen in connection with spectroscopically analyzing a plurality of varying or changing test samples. This is for the reason that with conventional systems in which the sample cells are moved relative to the spectroscopic analysis equipment, some means must be provided for allowing movement of the test cells having input and output conduits coupled to each of a plurality of individual test cells. That is, where the spectroscopic analysis system is being used to conduct spectroscopic analysis of a plurality of constantly changing test solutions, the test cells include fluid lines coupled thereto for the continuous introduction and withdrawal of the solution to be tested. Thus, when a plurality of such test cells are to be analyzed with the same scanning and detector equipment, provision must be made for physical movement of the test cells without completely tangling or fouling the fluid lines. Accordingly, with one known apparatus, a small plurality of test cells are supported on a movable support member, such as for example a turret, with the fluid lines for the various cells leading thereawayfron In order to prevent tangling or fouling of the fluid lines, it is necessary to reverse the movement of^'the movable support member after all of the cells have been tested so as to untangle the lines. Such an arrangement, however, would be totally unsatisfactory for use in connection with conducting an analysis of a large number of test cells. Furthermore, with prior art systems in which test cells are moved into and out of alignment with the scanner and detector equipment, the rate at which the test cells are moved is relatively slow. This is most significant and limits the usefulness of the prior art systems in connection with spectroscopical analysis of test samples in which fast chemical reactions take place and/or test samples in flow through test cells where .the properties of the test samples rapidly change.

Disclosure of Invention

In accordance with the present invention, there is provided an apparatus for use in spectroscopically analyzing properties of a plurality of test samples. The apparatus includes support means for stationarily supporting a plurality of test cells containing test samples to be analyzed, radiation directing means for directing a beam of radiation at the support means and radiation detector means for receiving output radiation from the support means. Mounting means are provided for mounting the radiation directing means and the radiation detector means in fixed relationship to one another, the mounting means being arranged with respect to the support means so that when the beam of radiation from the radiation detecting means is directed at one of test cells, the radiation detector means will be in position to receive output radiation from the one test cell. Moving means are also provided for moving the mounting means so as to successively direct the beam of radiation from the radiation directing means at the plurality of test cells so that the radiation detector means will successively receive radiation from the plurality of test cells.

Such an arrangement in which the test samples are stationarily supported relative to the beam of radiation and the detector means is most advantageous in connection with an apparatus for use in spectroscopically analyzing properties of a plurality of test cells whose contents are constantly changing. More specifically, with the apparatus of the present invention, the introduction into and withdrawal of the test solution from the test cells may be easily facilitated since the test cells remain stationary; there is no necessity of having to provide for physical movement of the introduction and withdrawal conduits. In accordance with a' preferred embodiment, the support means stationarily supports a plurality of test cells in an annular array. The radiation directing means is arranged at the central axis of the annular array and carries a support arm which extends radially outward from the radiation directing means. The radiation detector, means is supported by the support arm so as to be in.-a position to receive output radiation from the corresponding test cells at which the radiation directing means directs the beam of radiation. The radiation directing means, detector means and radially extending support arm are rotated together about the axis of the annular array of test cells so as to successively direct the beam of radia¬ tion from the radiation directing means at test cells. When the apparatus is being used in connection with spectroscopic concentration analysis of the test cells, the radiation directing means directs a beam of radiation through the test cell and the radiation detector means is located on the opposite side of the test cells to receive the output radiation passing therethroug .

Still further in accordance with the preferred embodiment, a source of radiation is provided for transmitting a source beam of radiation along the axis of the annular array of test cells. The radiation directing means comprises a mirror and lens arrangement for directing the beam of radiation from the source radially outward from the axis of the annular support towards the detector means. These and further features and characteristics of the present invention will be apparent from the following detailed description in which reference is made to the enclosed drawings which illustrate a preferred embodiment of the present invention.

Brief Description of Drawings

Figure 1 is a schematic plan view illustrat¬ ing operation of the apparatus in accordance with the preferred embodiment of the present invention.

Figure 2 is a perspective view, partially broken away, of the preferred embodiment of the apparatus in accordance with the present invention.

Figure 3 is a top plan view of the apparatus shown in Figure 2.

Figure 4 is a side sectional view of the apparatus taken along lines 4-4 of Figure 3 and illustrating schematically a suitable radiation source for transmitting a beam of radiation along the axis of rotation of the apparatus.

O PI Figure 5 is a sectional view taken along lines 5-5 of Figure 4.

Best Mode for Carrying Out the Invention

As the apparatus 10 of the present invention is particularly useful in connection with obtaining concentration measurements of a plurality of constantly changing test solutions, the present invention will be described mainly with respect to an apparatus for such particular use. However, it should be appreciated that the present invention is not limited to such use; rather, the apparatus 10 may be used in connection with spectroscopic analysis of many other types of properties of test samples, both from the viewpoint of qualitative analysis and quantitative analysis, and may be used in connection with such analysis based on either absorption or flourescence spectra. Furthermore, the present invention may be used in connection with spectroscopically analyzing other types of test samples. Referring now to the drawings wherein like reference characters represent like elements, there is illustrated in Figure 1 an apparatus in accordance with the preferred embodiment of the present invention for use in spectroscopically analyzing properties of a plurality of fluid test samples. The basic operation of the apparatus 10 in accordance with the present invention is illustrated schematically in Figure 1. The apparatus 10 includes a suitable stationary support means 12 for stationarily supporting a plurality of test cells 14 to be analyzed. As the apparatus 10 in the preferred embodiment comprises a spectrophotometer for use in connection with obtaining concentration data of fluid test samples, the support means 12 includes a plurality of test cells or cavities

_ OMPI 14 for receiving and holding fluid containers 16 into which fluid test samples are deposited. In the preferred embodiment, the test cells 14 are arranged in an annular array about the central axis 18 of the apparatus 10. The apparatus 10 also includes radiation directing means 20 for directing a beam of radiation radially outward from the central axis 18 for impinging on the test cells 14 annularly arranged thereabout. In this regard, each of the test cells 14 includes suitable passageways 22, 24 arranged with respect to the fluid samples for allowing light or other radiation to pass thereinto and through the solution, and to then exit from the cells 14. The passageways 22, 24 for example may comprise openings in the walls defining the inner and outer annular surfaces 26, 28 of the test cells 14. The radiation directing means 20 is axially arranged with respect to the support means 12 and test cells 14 so that the radially outwardly directed beam of radiation will pass through the inner radiation passageways 22^' of the cells 14 and be intercepted by the test solutions in each of the various cells 14. A suitable radiation detector 30 is arranged with respect to the stationarily supported test cells 14 for receiving output radiation exiting from the test cells 14. As the appratus 10 is mainly intended for use in connection with obtaining concen¬ tration measurements, based on the amount of radiation absorbed by the substance in the solutions being tested, the detector 30 in the preferred embodiment is arranged in alignment with the radially outwardly directed beam so that when the beam passes through the solution in one of the test cells 14 and exists through the outer radiation passageway 24, the detector 30 will detect the intensity of the radiation exiting from the cells 14. In order to insure alignment between the radially outward directed beam and the detector 30, the detector 30 is fixedly mounted on a support arm 32 extending radially outward from the radiation directing means 20 so as to be in direct alignment with the outwardly directed beam exiting from the radiation directing means 20 and so as to rotate with rotation of the radiation directing means 20. As the arm 32 is rotated, it will be appreciated from Figure 1 that the beam of radiation will successively impinge upon the test solution contained in the various test cells 14. Because of the alignment between the outcoming beam of radiation and the detector 30, the detector 30 will receive the output radiation exiting from the same test cells 14 into which the beam has been directed. In other words, when the beam is directed at test cell 34, the detector 30 will be in position to receive output radiation from test cell 34. Consequently, as the beam of radiation is rotated about the central axis 18 of the apparatus 10, a beam of radiation will be successively directed at each of the test samples supported in the annular array, and the detector 30 will in turn receive output radiation from the corresponding test samples on which the radiation has been directed. In this manner, it can be appreciated that a multitude of test samples may be quickly and efficiently analyzed.

In the preferred embodiment, the radiation directing means 20 comprises a mirror 36 arranged along the central axis 18 of the apparatus 10 to receive a beam of radiation along the central axis 18 and redirect the beam radially outward towards the test cells 14 and detector 30. In order to direct the beam of radiation successively at the various annularly arranged test cells 14, the mirror 36 or

OMPI other directing means is rotated about the central axis 18. A suitable lens 38 may be also employed for focusing and concentrating the beam of radiation at the test cells 14. Preferably, the lens 38 is fixedly mounted with respect to the reflecting mirror 36 and also rotates therewith.

Referring now to Figures 2-5 which illustrate a preferred embodiment of the present invention, the apparatus 10 includes a suitable base member 40 which houses the source 42 of radiation and on which is supported the test cell support means 12. The test cell support means 12 includes a lower circular plate 44 and an upper annular plate 46 fixedly supported together in coaxial alignment by means of a series of posts 48 arranged about the circumference of the lower and upper plates 44, 46. The upper annular support plate 46 in turn supports an annular test cell assembly 50 which includes an annular array of test cells or chambers 14 therein. More particularly, the test cell assembly 50 includes inner and outer spaced cylindrical ring sections 52, 54 Interconnected by a series of radial wall sections 56 circumferentially spaced about the inner and outer cylindrical ring sections 52, 54, the inner and outer cylindrical ring sections 52, 54 and radial wall section 56 together defining the plurality of test cells or chambers 14. As best seen in Figures 2 and 3, the test cells 14 are arranged in an annular array. The tops of each of the test cells 14 are opened for insertion and removal of the fluid containers 16, and the bottoms are closed by a suitable plate member 58. Each of the test cells 14 is of a rectangular cross sectional configuration and is adapted to receive a corresponding shaped fluid container 16 into which the sample solutions to be tested will be introduced. The test cell assembly 50 is suitably supported about the _ inner annular edge of the upper support plate 46 by suitable fasteners 60, such as for example screws.^'

The inner and outer cylindrical ring sections 52, 54 each include a series of passageways or apertures 22, 24 communicating with the interior of the test cells 14, the passageway 22 in the inner cylindrical ring section 52 being radially aligned with the passageway 24 in the outer cylindrical ring section 54 so that a beam of radiation directed radially outward from the central axis 18 and at the same elevation as the passageways 22, 24 will pass through the passageway 22 in the inner cylindrical ring section 52 through the cell 14 and exit therefrom through the corresponding passageway 24 in the outer cylindrical ring section 54. The fluid containers 16 for being received in each of the test cells 14 may either be constructed of a clear, light transmitting material or may have suitable light transmitting windows therein for the passage of radiation into and out of the fluid containers 16.

The test cell assembly 50 also carries and supports the radiation directing device 20 for rotation about the central axis 18 of the apparatus 10. More particularly, the test cell assembly 50 includes a downwardly depending support ring 62 which carries at its inner annular edge suitable bearings 64 for rotatably supporting a cylindrical support housing 66. The support housing 66 is of a generally hollow construction and supports at its upper end a hollow tubular member 68 to which a reflecting mirror 36 is mounted at an angle to receive a beam of radiation along the axis 18 of the apparatus 10 and to redirect same radially outward in a generally horizontal direction. More particularly in this regard, the

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_ OMPI hollow tubular member 68 includes an inclined upper end to which a cover plate 70 is mounted. The reflecting mirror 36 in turn is supported by the lower inclined surface of the cover member 70. Also, the mirror 36 is located so that the beam of radiation redirected thereby will be at the same axial elevation as the optical passageways 22, 24 in the test cell assembly 50. An optical condensing lens 38 is suitably mounted in the side of the hollow tubular member 68 for focusing and concentrating the beam of radiation redirected by the reflecting mirror 36.

A radially extending support arm 32 is suitably connected to the side of the cylindrical support housing 66 and extends radially outward beneath the test cell assembly 50. The support arm 32 in turn carries a suitable radiation detector 30 at.its outer end. The radiation detector 30 includes a suitable radiation receiving aperture (not shown) arranged at an elevation corresponding to the elevation at which the beam of radiation exits from the optical lens 38. Also, the radiation detector 30 is supported from the support arm 32 so that the radiation receiving aperture thereof is circumferentially located in alignment with the beam of radiation which exits from the optical lens 38. Accordingly, since the test cell passageways 22, 24 are at the same elevation as the beam of radiation redirected by the mirror 36, when the support housing 66 is rotated in its bearing 64, the beam of'radiation exiting from the optical lens 38 will be directed radially outward and pass successively through the test cell passageways 22, 24 of each of the test cells 14, with output radiation exiting from the outer passageways 24 in turn being received by the radiation detector 30. The cylindrical support housing 66 also_ includes a gear ring 72 mounted thereto directly below the position at which the support arm 32 is ^' mounted thereto. A motor 74 and drive gear 76 is supported by the lower support plate 44 of the apparatus 10 for driving a chain 78 entrained about the drive gear 76 and gear ring 72. As best seen in Figure 5, as the drive gear 76 is rotated, it will rotate the support housing 66 about the central axis 18 of the apparatus 10, which in turn will cause the directing device 20, the support arm 32, and the radiation detector 30 to rotate about the central axis 18 of the apparatus 10. Of course, it will be appreciated that other suitable drive arrangements could be provided for rotating the directing device 20, the support arm 32 and radiation detector 30, such as for example belt drive systems, direct gear driven systems, etc. The drive motor 74 can be controlled in any conventional manner to in turn control the speed and timing of rotation of the directing device 20, the support arm 32 and the radiation detector 30. For example, the motor may be driven continuously, in which case the directing device 20 and detector 30 will continuously rotate about the central axis 18 of the apparatus 10, or may be driven intermittently to index the directing device 20 and detector 30 from one test cell 14 to the next, etc.

A second hollow tube 80 is secured to the 'lower end of the support housing 66 for rotation therewith. The lower end of the second hollow tube 80 passes downwardly through a central aperture 82 provided in the lower support plate 44. In the preferred embodiment, electrical leads 84 for powering the detector 30 and for transmitting electronic information from the detector 30 pass radially inward along the support arm 32 and downwardly through the central aperture 82 in the lower support plate 44. Excess electrical leads (not shown) are provided beneath the lower support plate 44 so as to provide a wire-wrap mechanism while the directing device 20, support arm 32 and radiation detector 30 rotate. In this regard the amount of excess leads is sufficient to permit the detector 30 to complete at least one revolution about the test cells 14. With this type of arrangement, it will thus be appreciated that movement of the detector 30 must be reversed and the detector 30 returned to its initial start position after the electrical leads 84 have wrapped around the lower tube 80. However, _;it will also be appreciated that such a wire-wrap arrangement can be avoided by the use of a slip-away assembly, sliding electrical contacts or other known electrical transmission devices for making electrical connections between stationary portions of an apparatus and rotating portions.

The electrical output from the detector device 30 is transmitted to a suitable readout or display device 86 for displaying the readings made of the various test samples. Of course, it will be appreciated that such readout or display device 86 may include a central processor unit for processing the electrical output and providing different sets of readings and information respecting the test samples based upon the readings of the detector 30. The display device 86 and the types of information generated as a result of the radiation received by the detecting device 30 form no part of the present invention, and therefore a description of same will not be presented. In this regard, it is noted however that such devices and types of information generated with the information from the detector device 30 are well known to persons skilled in the art.

In order to provide a beam of radiation ^'for impingement upon the test samples 14, a suitable source 42 of radiation is provided for transmitting a beam of light along the axis 18 of rotation of the directing device 20. A suitable system in this regard is shown schematically in Figure 3 housed within the lower support housing 40 of the apparatus 10. A suitable light source 88 is provided which when energized directs radiation onto a mirror 90 which in turn reflects the light through an aperture 92 onto a defraction grating 94. The defraction grating 94 is rotatable so as to provide an essentially monochromatic beam of radiation of a desired wavelength, depending upon the nature of the test samples, the properties of the test samples to be measured, etc. Generally, the wavelength of the radiation will lie in the visible and ultraviolet light ranges, although lower and higher wavelength radiation may be used in connection with some types of spectroscopic analysis. From the defraction grating 94, the beam of essentially monochromatic light is directed onto a mirror 96 which in turn transmits the beam of radiation axially upward along the axis 18 of the apparatus 10. The beam of radiation is received and reflected by the mirror 36 located on the directing device 20 and redirected radially outward through the optical lens 38. It will be appreciated that since the beam of monochromatic radiation from the radiation source is directed along the axis 18 of rotation of the directing device 20 and since the mirror 36 of the directing device 20 is also located along the axis 18, rotation of the directing device 20 will not affect transmission of the radiation; the directing device 20 will still

receive the radiation and direct same radially outward during rotation. The radiation source 42 schematically shown in Figure 4 is of a conventional construction and well known in the art, and only constitutes a schematic representation of a suitable source of radiation. Of course, depending upon the properties of the test samples being analyzed and the type of spectroscopic analysis to be made, other types of radiation sources may be utilized. The only requirement in accordance with the preferred embodiment is that the beam of radiation be directed along the axis 18 of rotation of the radiation directing device 20. The apparatus 10 in accordance with the present invention is particularly useful in connection with conducting spectroscopic analysis of test samples whose properties are constantly varying.. For example, when concentration type analysis is being performed, such as for example in connection with dissolution testing, the concentration levels of particular samples will vary over time. In order to evaluate such changes in concentration, it is desirable to continuously or periodically test the various solutions over time. This may be easily accomplished with the apparatus 10 of the present invention which provides for stationarily supporting the test cells 14. More particularly in accordance with the preferred embodi¬ ment, the fluid containers 16 received within each of the test cells 14 includes a pair of fluid conduits 17a, 17b coupled thereto which are connected, respec- tively, to the source of sample fluid and to an output device or drain. A test solution is continuously pumped into and then withdrawn from each fluid containers 16 mounted in the test cells 14. Because the test cells 14 are stationary with respect to the directing device 20 and radiation detector 30, problems

OMP in introducing and withdrawing fluid from the test cells 14 are minimized since the lines 17a, 17b may simply be attached to the stationary test cells 14. Consequently, a relatively large number of test cells 14 may be provided in the apparatus 10. In the embodiment shown in the figures, the number of test cells annularly supported by the support means 12 is on the order of 50. Of course, larger numbers of test cells 14 or few test cells 14 could be provided if desired.

As is well known, the type of radiation detector 30 utilized must be compatible with the radiation source 42 being utilized in connection with the spectroscopic analysis. In other words, there must be a matching between the radiation detector 30 and the radiation source.42, although a number of different radiation detectors can be utilized with respect to a number of different types of sources. In the embodiments shown and described hereinabove, the radiation source 42 may comprise the radiation source component of a Hitachi Model 100-20 single beam spectrophotometer, and the radiation detector device 30 may comprise the detector component of the same Hitachi Model 100-20 machine. Generally, suitable radiation detector devices which may be used in connection with conducting concentration measurements include photomultiplier tubes, solid state photodiodes, and vacuum photodiodes. Of course, it will be appreciated that when other, types of spectroscopic analysis are to be performed with respect to test samples, other types of detector devices may be employed.

Also, in the preferred embodiment, a suitable sensing device 98, such as for example an LED optical pick-up is provided for sensing when the radiation detector device 30 is in a reference or "0" position. The sensing device 98 is mounted adjacent the location of the motor 74, and a suitable flag 99 for activating the sensor device 98- is secured to the radiation detector device 30. When the flag 99 passes the sensing device 98, a signal will be generated to stop the motor 74 to thereby stop rotation of the directing device 20 and detector 30. Such sensing device 98 for use in precise positioning of moving elements or components are well known, and therefore the operation and control thereof need not be described in detail. In the present apparatus, the sensing device 98 may be used in connection with positioning of the directing device 20, support arm 32_; and radiation detector 30 for conducting a new set of spectroscopic analysis and/or for unwinding of the electrical leads 84 from the hollow tube 8.0. Further, the sensing device 98 may be useful in connection with repeating certain specified measurements or analysis of selected cells 14 by providing a reference or start position. Still further, conventional techniques for the control of the position of the radiation detector device 30 and directing device 20, the speed of rotation, etc. may be employed. For example, when continuous measurements are to be made, i.e., when the detector 30 and the directing device 20 are being rotated on a continuous basis, suitable controls may be provided for determining at which points or positions meaningful information is being received, i.e., at what point in time the beam of radiation is being directed onto the various test cells 14. In this regard, the accuracy of the detector device 30 and the speed of processing (i.e., the rate at which the detector 30 may receive and process information) will govern the rate at which samples may be analyzed. However, with the present day equipment, it is possible to achieve accurate_ readings of the test samples at scanning speeds on the order of one cell per second.

As noted above, although the preferred embodiment of the present invention is directed for use in connection with obtaining concentration measure¬ ments of fluid test samples, the apparatus 10 is equally applicable for^' use in connection with other absorption, transmission, and excitation measurements in the analytical chemistry field where the main cost in the equipment is in the source 42 and the detector 30, and not in the samples themselves. With the apparatus 10 of the present invention, multiple test samples can be measured rapidly and efficiently with the same scanning and detector apparatus. This is particularly important with respect to systems for spectroscopically analyzing test samples in which fast chemical reactions take place and/or test samples in flow through test cells where the properties of the test samples rapidly change.

Accordingly, it is seen that in accordance with the present invention there is provided an apparatus 10 for use in spectroscopically analyzing properties of a plurality of test samples. Support means 12 are provided for stationarily supporting a plurality of test cells 14 containing test samples to be analyzed, and radiation directing means 20 are provided for directing a beam of radiation towards the support means 12. Radiation detector means 30 are also provided for receiving radiation output from the support means 12, the radiation detector means 30 and radiation directing means 20 being mounted by mounting means 32 in fixed relationship to one another. The mounting means 32 is arranged with respect to the support means 12 so that when a beam of radiation

OMPI from the radiation directing means 20 is directed.at one of the test cells 14, the radiation detector means 30 will receive output radiation from the same test cell 14. Moving means 72, 74, 76, 78 are provided for moving the mounting means 32 so as to successively direct the beam of radiation from the radiation directing means 20 at the plurality of test cells 14 so that the radiation detecting means 30 will succes¬ sively receive output radiation from the plurality of test cells 14. In the preferred embodiment, the test cells 14 include fluid containers 16 having input and output fluid conduits 17a, 17b coupled thereto for the continuous introduction and-withdrawal of test solutions. While the preferred embodiment of the present invention' as been shown and described, it will be understood that such is merely illustrative and that changes may be ma^'de without departing from the scope of the invention as claimed.

Claims

1. An apparatus for use in spectroscopically analyzing properties of a plurality of test samples, said apparatus including a plurality of test cells for containing test samples to be analyzed, radiation directing means for directing a beam of radiation at said test cells and radiation detector means for receiving output radiation from said test cells, said apparatus being characterized by support means (12) for stationarily supporting said plurality of test cells (14), mounting means (32, 66) for mounting said radiation directing means (20) and said radiation detecting means (30) in fixed relationship to one another, said mounting means being arranged with respect to said support means so that when said beam of radiation from said radiation directing means is directed at one of said test cells said radiation detection means will receive output radiation from said one test cell; and moving means (72, 74, 76, 78) for moving said mounting means so as to successively direct said beam of radiation from said radiation directing means at said plurality of test cells so that said radiation detector means will successively receive output radiation from said plurality of test cells.

2. The apparatus of Claim 1, characterized by the fact that said support means stationarily supports said plurality of test cells in an annular array arranged about a central axis (18) of said support means, and said moving means rotates said mounting means about said central axis.

3. The apparatus of Claim 2, characterized by a radiation source (42) for transmitting a source beam of radiation along said central axis, and by the fact that said mounting means mounts said radiation directing means along said central axis to receive said source beam of radiation and to redirect said source beam radially outward from said central axis.

4. The apparatus of Claim 3, characterized in that said radiation directing means comprises a mirror (36) disposed along said central axis to intercept said source beam of radiation and to redirect said source beam radially outward from said central axis.

5. The apparatus of Claim 4, characterized by the fact that said radiation directing means further includes a lens (38) for condensing said beam of radiation redirected by said mirror.

6. The apparatus of any one of the Claims

2-5, characterized in that said support means comprises an.annular support ring (50) having a central axis and having said plurality of test cells arranged in an annular array about said central axis of said support ring, and in that said mounting means comprises a support housing (66) for supporting said radiation directing means along said central axis of said support ring and a radially extending support arm (32) extending radially outward from said support housing and supporting said radiation detector means at a radial position spaced from said central axis.

7. The apparatus of Claim 6, characterized in that said mounting means further includes rotational support means (64) for rotatably supporting said support housing from said annular support ring.

8. The apparatus of Claim 6 or 7, charac¬ terized in that said support means further includes a support member (46, 44) for supporting said annular support ring, and in that said moving means is coupled to said support member and said support housing for rotating said support housing about said central _ axis.

9. The apparatus of Claim 8, characterized in that said support member includes first and second support plates (46, 44) positioned in axial spaced relationship to one another, said annular support ring being supported from said first plate (46), and in that said moving means comprises drive means (74, 76) supported by said second support plate (44) and drive transmission means (78, 72) coupling said drive means to said support housing.

10. The apparatus of any one of the Claims 1-9, characterized by the fact that each of said test cells includes a fluid container (16) for containing a fluid test sample and conduit means (17a, 17b) coupled to said fluid container for introducing and withdrawing fluid from said fluid container, each of said fluid containers being adapted to receive radiation therethrough from said radiation directing means and to transmit output radiation therefrom to be received by said radiation detector means.