US3425806A - Method and means for detecting a halogen or phosphorus in a gaseous material - Google Patents

Description

Feb. 4, 1969 KARM EN 3,425,806

A. METHOD AND MEANS FOR DETECTING A HALOGEN OR PHOSPHORUS IN A GASEOUS MATERIAL Filed March 22, 1965 sheet of 2 t\\ \\\1 50 A: 50 ha m FIG I l4 /2 19 MIR g 6 5 q a O E 8 FIG. 2 I g '6 '0 w I O Q U 0 n IL I Q 9 f 0 5 n D I O O INVENTOR Arthur Karmen ATTORNEYS Feb. 4, 1969 A. KARMEN 3,425,806-

METHOD AND MEANS FOR DETECTING A HALOGEN OR PHOSPHORUS IN A GASEOUS MATERIAL Filed March-22, 1965 H IQ IO I U E m X 0 R D Y 5 M B HM Fm T O P SCREEN 31o NIQDINQ FIG 4 SODIUM NlTRATE-NlTRIC ACID SCREEN LO 1g CH-Cls INVENTOR Arthur Karmen BY t ATTORNEYS y 3/ 9 39 m6 mm m w JH OH O.H .C 0 0C 0 O W United States Patent 3 425 806 METHOD AND MEANS FOR DETECTING A HALOGEN OR PHOSPHORUS IN A GASEOUS MATERIAL Arthur Kai-men, Baltimore, Md., assignor to the United States of America as represented by the Secretary of Health, Education, and Welfare Filed Mar. 22, 1965, Ser. No. 441,486 US. Cl. 23232 30 Claims Int. Cl. G0ln 27/62 ABSTRACT OF THE DISCLOSURE A method and means for detecting the presence of a halogen or phosphorus in a gaseous material is disclosed. The halogen or phosphorus is detected by monitoring the rate of vaporization of a metallic material, which rate increases when a probe containing such metallic mater1al is heated in the presence of a sample containing one of those elements. The rate of vaporization of the metallic material is measured by a flame ionization detector or flame photometry device. The metal could be an alkali metal, barium, strontium, calcium and mixtures of the same, and could be in the form of a pure metallic material, a metallic amalgam, a metallic salt and mixtures of the same.

This invention relates to a method and means for detecting the presence of a compound having an element selected from the group consisting of halogens and phosphorus in a gaseous material and relates more particularly to the detection of such an element by monitoring the rate of vaporization of a metallic material which rate increases when a probe containing the metallic material is heated in the presence of the element.

Various means are known for detecting, identifying and measuring minute quantities of particular chemical compounds in mixtures of the same. Gas chromatography is one particularly useful research tool for such use. Recently, flame ionization detectors have been used in conjunction -with gas chromatograph devices to further improve the analysis of a gaseous mixture. The basis of operation of flame ionization detectors is that when organic compounds are burned in a flame such as a hydrogen flame or a carbon monoxide flame the electrical conductivity of the flame is increased. Other detecting means such as flame photometry devices are also well known, these structures functioning to measure the characteristic color imparted to the flame by various chemical compounds.

The instant inventive concept makes use of the discovery that certain metallic materials are volatilized or vaporized at an increased rate when heated in the presence of a halogen or phosphor-us. Thus, if a gaseous material containing a compound having such an element is impinged upon a heated probe including the metallic material, the increased rate of vaporization of the metallic material caused by the presence of the element can be detected by any conventional means such as various flame ionization or flame photometry techniques.

The method and means of this invention according to a further feature of the inventive concept take advantage of the fact that a flame ionization detector is not sensitive to organic compounds after these have been subjected to combustion, but remain sensitive to certain metallic vapors under the same conditions. Thus, it is possible to detect a compound having one of the aforementioned elements in the presence of a variety of element-free organic compounds, that is, organic compounds having neither a halogen nor a phosphorus atom in their structure, even when the compound including the element is 3,425,806 Patented Feb. 4, 1969 present in a relatively small quantitative ratio with respect to the other compounds. This technique also makes possible the development of specific methods for detecting families of compounds with functional groups replaceable by one of the specified elements by snythesizing an element-containing derivative of the compound using reagents containing the element and reactive with the functional group.

According to a preferred embodiment of the instant invention the gaseous material undergoing investigation may be subjected to two flame ionization procedures, the first functioning to simultaneos-uly combust the gaseous materials while detecting its organic constituents, and the combusted gaseous material from the first flame impinging upon a probe including the metallic material to cause increased rates of vaporization of the same under the influence of element-containing compounds in the gaseous material, this increased rate of vaporization being detected by a second flame ionization means which is not sensitive to the organic compounds which were in the original gaseous material since these compounds have been subjected to combustion producing various nondetected carbon, hydrogen and oxygen containing vapors. Consistent with this preferred embodiment separate monitoring of the two flames will provide a more detailed picture of the make-up of the gaseous material. This double flame ionization technique can preferably be utilized in conjunction with gas chromatography by feeding the effluent from the gas column to the first flame.

Additionally, the double flame detector described above can be improved by interposing an electrostatic shield between the two flames which defines the volume of gas of which the electrical conductivity is to be measured, this shield preferably including the metallic material to thereby simultaneously serve as the probe. ][t is to be understood that the use of the term probe herein is intended to include any conventional form of such members as well as the preferred foraminous element such as a screen which serves in the dual capacity as a metallic vapor source and an electrostatic shield.

Quantitative results can be readily realized according to the instant inventive concept by comparing the increased rate of vaporization of the metallic material caused by a gaseous mixture having an unknown quantity of a compound including the particular element defined above with increased rates of vaporization of the metallic material caused by various gaseous materials having known quantities of compounds including such elements.

Consistent with the above it is a primary object of the instant invention to provide a method and means for detecting the presence of a halogen or phosphorus in a gaseous material which is extremely sensitive to relatively small quantities of such elements and which is particularly specific to such elements.

A further object of this invention is the provision of a detection technique which can readily identify quantitatively minute amounts of such elements in a mixture containing relatively large quantities of other compounds.

Yet another object of the instant invention is the provision of a method for detecting families of compounds with specific functional groups such as alcohols or amines which are replaceable by the element causing sensitivity of the detector by synthesizing an element-containing derivative of the compound thereby confirming the presence of the compound in the original gaseous material.

Another object hereof is to provide a unique detector device which is relatively durable in construction inexpensive to manufacture and maintain, and reliable and eflicient in operation. Further, the preferred device of this invention has various means serving dual functions such as a lower burner which simultaneously will provide a flame ionization study of the original gaseous material and combust the same before impinging the gas on a probe containing the metallic material, the probe preferably also serving as an electrostatic shield to facilitate separately monitoring the electrical conductivities of the two flames.

Other and further objects reside in the combination of elements of the apparatus disclosed herein and the specific manipulative steps of the methods set forth.

Still other objects will in part be obvious and in part be pointed out as the description of the invention proceeds and as shown in the accompanying drawings wherein:

FIGURE 1 is a schematic cross-sectional view of a preferred form of detector device according to the instant inventive concept; and

FIGURES 2-6 show the flame ionization curves produced by the upper and lower burners of a device similar to FIGURE 1 when a gaseous material containing certain specific organic compounds are treated therein.

Like reference characters refer to like parts throughout the several views of the drawings.

Referring now to the basic concept of the instant invention, as pointed out hereinabove, a probe is provided including a metallic material which vaporizes or volatilizes at an increased rate when heated in the presence of a halogen or phosphorus. If a flame ionization technique is to be utilized to detect the increased rate of vaporization of the metallic material in a manner to be described in more detail hereinafter, the metallic material is selected from the group consisting of alkali metals, barium, strontium, calcium and mixtures of the same, the metallic material being in the form of a substantially pure metallic compound, a metallic amalgam or a metallic salt, preferably a hydroxide, nitrate, sulfate or chloride. Although the list of metallic materials set forth includes calcium, it is pointed out that the other metals are preferred since the increased rate of vaporization of calcium is relatively small when compared thereto. However, since this material will function to provide a detectable signal, it is to be considered as within the useful group. The probe may integrally include the metallic material such as a member having the metallic material as a constituent of the same. For example, a sodium-platinum amalgam can be used as the probe. Alternately, the probe may comprise an inert, heat-resisting base material such as stainless steel, platinum or other similar materials dipped into a solution of one of the metallic salts mentioned above to provide a coating layer on the base. Further, it has been found that commercially purchased platinum wire per se normally includes a sufficient proportion of sodium to function as a probe for the device of the instant invention.

If other than flame ionization means are to be utilized to detect the increased rate of vaporization, different metallic materials may be utilized. For example, if the detection means is a flame photometry device, other well known metallic materials may be provided. The primary criterion for choosing a material which is to be included in or on the probe is that its rate of volatilization or vaporization be markably increased when heated in the presence of a halogen or phosphorus.

It is of course important that the probe be heated in order to effect the vaporization of the metallic material. Separate heating means may be provided for the probe in any conventional manner. Additionally, the probe can be automatically heated by elevating the temperature of the gaseous material before impinging the same on the probe such as in the preferred embodiment of this invention to be described in more detail hereinafter.

Although the method and means of the instant invention are not limited to such use, they can preferably be combined with a gas chromatograph apparatus which functions in a conventional manner. As exemplary of such devices, experiments have been conducted utilizing columns of five feet in length formed from straight glass tubes having a five millimeter internal diameter. These columns were packed with ethylene glycol adipate polyester, 14 percent, on Gas-Chrom P, 86 percent (Applied Science Corporation), or with Carbowax 400, 5 percent (Union Carbide Corporation), on Chromosorb-W, percent (J ohns-Manville Corporation) or with SE30 silicone gum, 1 percent (General Electric Company), on Chromosorb-W, 99 percent. Of course, other conventional gas chromatography devices could readily be utilizedfThe effluent from such columns preferably forms the gaseous material which is utilized in the method and means of this invention.

According to the preferred procedure hereof, the detection means is in the form of a flame ionization technique which, as pointed out hereinabove, determines the composition of a gaseous material by monitoring the electrical conductivity of a flame which receives the same and which is additionally supplied with a gas such as hydrogen or carbon monoxide. Many conventional procedures are known for so monitoring the electrical conductivity and it is to be understood that those specifically discolsed herein are merely illustrative. According to a further feature of this invention, the presence of an organic compound having a functional group replaceable by a halogen or phosphorus in the original gaseous material may be confirmed by reacting the same with a reagent including such an element to produce a substituted derivative of the organic compound which includes either the halogen or the phosphorus, this gaseous material then being impinged upon the heated probe to increase the rate of vaporization of the metallic material for detection.

If the original gaseous material is to be subjected to combustion prior to impinging the same against the probe in the manner of the preferred embodiment of this invention, in order to transform those organic materials not containing halogen or phosphorus to various carbon, hydrogen or oxygen containing constituents not normally detectable by the later flame ionization detection means, the instant inventive concept can be further utilized in an advantageous manner. Presu'ming the original gaseous material includes only one organic compound which has a functional group capable of being replaced by a halogen or phosphorus upon contact with a specific reagent, and one or more other organic compounds which do not so react with the reagent, the original gaseous material may be treated to form the halogen or phosphorus-substituted derivative of the one organic compound, the gaseous mixture then being subjected to combustion prior to impinging the same on the heated probe. In this manner the presence of the one Organic compound in the original gaseous material will be confirmed by detection of the increased rate of vaporization of the metallic material from the probe caused by the presence of the halogen or phosphorus-substitued derivative of the same. As exemplary of this procedure a gaseous material having a relatively small quantity of methanol in the presence of large quantities of other organic materials such as, for example, benzene, toluene or the like can be reacted with trichloroacetic anhydride to form methyl trichloroacetate, the gaseous material after combusion being impinged on a probe and the presence of the chlorine-substituted derivative of methanol being detected by the increased rate of vaporization of the metallic material from the probe.

Additionally, it is within the instant inventive concept as pointed out hereinabove to run a series of control samples of gaseous materials having known quantities of compounds including a particular halogen or phosphorus and compare the increased rates of vaporization of the metallic material from the probe caused by such gaseous materials with the increased rate of vaporization of the metallic material caused by a gaseous material having an unknown quantity of a compound including the said element, thereby quantitatively determining the amount of the element in the unknown gaseous material.

Although the basic concept of this invention has been applied generally to all halogens and phosphorus, it will be readily understood that each of these elements will be more or less readily detected. For example, fluorinecontaining compounds provide a much less sensitive response than those realized with the other halogens. The magnitude of the sensitivity will vary with the particular metallic material in the probe, and although the sensitivity to fluorine is not optimum, in certain instances a definite response can be obtained. On the other hand, the sensitivity of the detector of this invention to phosphorus is generally much greater than that of an equal weight of a halogen such as chlorine depending upon the particular metallic material utilized in the probe. As will be shown hereinafter the relative sensitivity of the detector to bromine, chlorine and iodine-containing compounds will vary somewhat with the particular metallic material in or on the probe. Generally, the relative response of the detector to compounds containing diflerent quantitative amounts of a particular halogen or phosphorus will be in direct proportion to the quantity of the element present.

With the above general description of the broader scope of the instant inventive concept in mind, a more specific detailed account of the preferred embodiment of the invention will now be described with particular reference to the drawings. In FIGURE 1 a preferred form of the device for practicing the procedure of this invention is schematically shown and will be seen to include a base or support provided with an air or oxygen-containing material inlet 12, a hydrogen inlet 14 (it being understood that the hydrogen gas may be replaced by other operable materials such as carbon monoxide) and a further inlet 16 connected to a source of gaseous material to be investigated, prefer-ably the efliuent from a column of a conventional gas chromatograph apparatus (not shown). Inlets 14 and 16 each communicate with a common passageway 18 which terminates in a burner device schematically shown at 20 having a flame 22. It will be readily understood that the burner device 20 may be supported in any desired manner. In the particular construction shown in the drawings the flame 22 is confined within a lower chamber 24 defined by the lower portion 26 of a continuously extending housing 28 which is grounded in any conventional manner (not shown). The electrical conductivity of the flame 22 may be readily monitored by any of a variety of well known means, a ring electrode 30 circumscribing the flame 22 being shown as illustrative. This ring electrode may be supported in any desired manner, a block 32 secured to the housing 28 being shown in the drawings. Of course, the ring electrode 30 must be insulated from the other electrode which is defined by the grounded housing 28. Conductors (not shown) may connect the electrodes to a conventional monitoring means (not shown) such as an electrometer or the like in a well known manner. A flanged angular bracket 34 is shown as supporting the housing 28 on the base 10.

An upper burner device 36 having a flame 38 is illustrated as confined in an upper chamber 40 defined by the upper portion 42 of the housing 28, this burner similarly being fed by a source of hydrogen and nitrogen (which is a conventional carrier gas in a chromatograph column) and being supported as desired above the lower burner device 20. Similar means for monitoring the electrical conductivity of the flame 38 are provided in the form of a ring electrode 44 carried by a block 46 and insulated from the housing 28. A removable cover member 48 is carried by the upper portion 42 of the housing 28, vents 50 in the cover member 48 being provided to permit escape of combustion products and other gaseous materials rising from the interior of the housing 28.

Although, as pointed out hereinabove, the probe may take any conventional form, according to the preferred embodiment shown in the drawings, it is comprised by a foraminous electrically conductive member 52 in the form of a screen or the like removably supported on an angular bracket 54 to permit replacement or retreating of the same, as necessary. The screen 52 may be constructed by spot welding stainless steel mesh (50 by 50 Surgaloy mesh, Davis and Geck Company) or platinum wire gauze 52 mesh (Fisher Scientific Company) around the circumference of a flat stainless steel ring 56. The screen 52 thus acts as an electrostatic shield between the flames 22 and 38 to permit accurate and separate monitoring of the electrical conductivities of each flame. The metallic material which volatilizes or vaporizes at an increased rate when heated in the presence of a halogen or phosphorus may either be an integral part of the wires forming the screen 52 or the screen may be dipped into a solution of a salt of the metallic material as described hereinabove.

The use and operation of the device shown in FIG- URE 1 will now be apparent. The gaseous material being studied is fed to the lower burner device 20 through the inlet 16 and intermixed with hydrogen or the like from the inlet 14, combustion being supported by the air entering through passageway 12 to form the flame 22. In effect, the lower burner device 20 functions to combust the gaseous material fed through the inlet 16 while simultaneously acting as a flame ionization means to provide a general record of the constituents of the gaseous material. The combusted gaseous materials rising from the flame 22 impinge upon the probe or screen 52 concomitantly heating the same and causing an increased rate of vaporization of the metallic material in or on the screen due to the presence of the halogen or phosphorus in the original gaseous material. The vaporized metallic material diffuses upwardly from the screen 52 to be received by the flame 38 of the upper burner device 36 wherein a second flame ionization technique is performed by monitoring the electrical conductivity of the same thereby detecting the presence of the halogen or phosphorus-containing compound indirectly. The curve resulting from the upper flame ionization procedure will be specific to the, halogen or phosphorus-containing material since it is non-responsive to the combusted products of the other organic materials in the original gaseous material Which form carbon dioxide, water or other carbon, oxygen and hydrogen containing compounds. Additionally, no response will be received from various other materials such as sulphur or nitrogen containing compounds in the gaseous mixture.

To further illustrate the instant inventive concept, various curves are shown in FIGURES 2-6 of the record of the electrical conductivities of the two flames. In FIG- URE 2 a sample of diethyl ether solution containing on a volume basis (1) 0.1 percent of carbon tetrachloride, (2) 1.0 percent of fluorobenzene, (3) 1.0 percent of toluene, and (4) 1.0 percent of chlorobenzene. The upper graph is the record of the electrical conductivity of the lower flame 22 and the lower graph is the record of the electrical conductivity of the upper flame 38 of a detector such as shown in FIGURE 1. It will be seen that the upper flame ionization record shows distinct responses to the chlorine containing compounds with substantially no response to the combusted fluorobenzene and toluene. While this particular analysis failed to detect fluorine, as pointed out hereinabove, in certain specific instances fluorine will provide a definite response and it is for that reason that this element is included within the instant inventive concept. The combination of variables which will provide a fluorine detection can be readily determined by those with ordinary skill in the art by experimentation utilizing the teachings of this disclosure.

FIGURE 3 shows the analysis of a diethyl ether solution containing by volume (1) 1.0 percent acetone, (2) 0.1 percent chloroform, (3) 1.0 percent toluene, and (4) 1.0 percent chloroibenzene. Once again, the chlorine containing constituents show a strong signal in the curve 7 of the electrical conductivity of the upper flame 38 (the lower curve in FIGURE 3) which specificity is not realized by the flame ionization record of the lower flame 22.

The relative sensitivity of the detector to butyl bromide, chloride and iodide varied somewhat when screens treated with different cations were used. The sensitivity to butyl bromide was greater than to butyl chloride or butyl iodide with each of the screens. The relative sensitivity to ibutyl chloride was higher when a screen treated with potassium hydroxide was used as will be seen in FIGURE 5, the responses not being as great with a sodium nitrate-nitric acid treated screen as shown in FIGURE 4.

The usable sensitivity of the detector to chloroform was assessed by preparing solutions containing graded amounts of this material in a solvent consisting of 1 percent toluene in diethyl ether. Three nanograms of chloroform could be distinguished from base-line noise. At the same sensitivity setting there was no response to 1.0 percent toluene, the chloroform record being designated as 1 and the toluene record being designated at 2, the curve on the right hand side of the legend in FIG- URE 6 being that of the lower flame ionization technique and the curve on the left hand side of the legend being that of the upper flame ionization flame technique. Less than 0.3 nanogram of chloroform could be distinguished from noise of the same band width using the same screen. It is noted that the peak 1 on the records of the lower flame is not reduced as the chloroform is reduced below 0.3 percent indicating a probable contaminant in the reagents. That this contaminant did not contain the halogen will be readily seen by the record of the upper flame conductivity.

The sensitivity of the detector to phosphorus was determined by analyzing graded amounts of triethyl phosphate. The records of this analysis are not shown on the drawings, but 1 nanograrn of triethyl phosphate emerging from a column so that a peak with a base width of 30 seconds was recorded, could be distinguished from base-line fluctuations with a :1 signal to noise ratio.

It will be obvious that the responsiveness of the detector will change with variation in the temperature of the screen and therefore with variations in the size and temperature of the lower flame and also with variations in the size and temperature of the upper flame as well. Therefore, it is necessary to calibrate the response of the detector to obtain quantitatively reliable results. Analysis of a sample containing different quantities of two of three halogen-containing substances and enough of a nonhalogen-substance to be detected easily in the lower flame readily permits a response curve to be constructed.

While the sensitivity of the detector will decrease gradually as the metallic material is evaporated from the screen by the flame, this process takes many days. The

detector shown in FIGURE 1 is constructed so that the screen may be readily removed and replaced as necessary.

Samples containing methylene dichloride, chloroform, and carbon tetrachloride were prepared so that the peak heights (not shown in the drawings) were grossly similar. The relative response of the detector to each of these compounds was in direct proportion to the amount of chlorine present.

Thus, it will now be seen that there is herein provided an improved detection means and method for identifying the presence of halogens and phosphorus in a gaseous material in the presence of a variety of organic compounds, even when the former element is available only in very small quantities in relation to the latter compounds. This method provides one of the most sensitive as well as specific methods for detecting phosphorus, and one of the most specific, as well as highly sensitive methods for detecting halogens. It is also a novel example of applying a highly sensitive, relatively nonspecific gas chromatography detector to the design of a highly specific, as well as sensitive detection method. Basically, as pointed out hereinabove, the preferred method and means of this invention take advantage of the fact that a flame ionization detector is not sensitive to organic compounds after they have been subjected to combustion, but remain sensitive to certain metallic vapors under the same conditions.

Since many embodiments may be made of the instant inventive concept, and since many modifications may be made of the embodiments hereinbefore shown and described, it is to be understood that all matter herein is to be interpreted merely as illustrative and not in a limiting sense.

What is claimed is:

1. A process for detecting the presence in a gaseous material, said gaseous material being the effluent from a gas chromatography column, of a compound having an element selected from the group consisting of halogens and phosphorus comprising providing a probe including a metallic material which vaporizes at an increased rate when heated in the presence of said element, said metallic material being selected from the roup consisting of alkali metals, barium, strontium, calcium and mixtures of the same, heating said probe, impinging said gaseous material against said 'probe, and detecting the increased rate of vaporization of said metallic material as an indication of the presence of said compound.

2. A process for detecting the presence in a gaseous material of phosphorus comprising providing a probe including a metallic material which vaporizes at an increased rate when heated in the presence of said phosphorus, said metallic material being selected from the group consisting of alkali metals, barium, strontium, calcium and mixtures of the same, heating said probe, im pinging said gaseous material against said probe, and detecting the increased rate of vaporization of said metallic material as an indication of the presence of said phosphorus.

3. A process for detecting the presence in a gaseous material of a compound having an element selected from the group consisting of halogens and phosphorus comprising providing a probe including a metallic material which vaporizes at an increased rate when heated in the presence of said element, said metallic material being selected from the group consisting of alkali metals, barium, strontium, calcium and mixtures of the same, heating said probe, impinging said gaseous material against said probe, and detecting the increased rate of vaporization of said metallic material as an indication of the presence of said compound, said increased rate of said metallic material being detected by a flame ionization detector technique, said flame ionization detector technique including monitoring the electrical conductivity of a flame which receives the vaporized metallic material released from said probe.

4. A process in accordance with claim 3 wherein said flame includes a gas selected from the group consisting of hydrogen and carbon monoxide.

5. A process in accordance with claim 3 wherein said metallic material is in a form selected from the group consisting of a substantially pure metallic material, a metallic amalgam, a metallic salt and mixtures of the same.

6. A process in accordance with claim 3, further including detecting the increased rate of vaporization of the metallic material from gaseous materials having known quantities of compounds including said element, feeding a predetermined rate of a gaseous material having an unknown quantity of a compound including said ele ment, detecting the increased rate of vaporization of the metallic material caused by said last-mentioned gaseous material and comparing the same with the increased rates of vaporization of the metallic material caused by the first-mentioned gaseous materials, thereby quantitatively determining the amount of said element in said lastmentioned gaseous material.

7. A process in accordance with claim 3 wherein said gaseous material originally includes an organic compound having a functional group replaceable by said element, further including reacting the original gaseous material with a reagent including said element to produce a derivative of said organic compound including said element before impinging the gaseous material containing said derivative of said organic compound against said heated probe and detecting the increased rate of vaporization of the metallic material whereby the presence of said organic compound in said original gaseous material is confirmed.

8. A process for detecting the presence in a gaseous material of a compound having an element selected from the group consisting of halogens and phosphorus said gaseous material additionally including at least one organic compound free of said element, comprising providing a probe including a metallic material which vaporizes at an increased rate when heated in the presence of said element, said metallic material being selected from the group consisting of alkali metals, barium, strontium, calcium and mixtures of the same, heating said probe, subjecting said gaseous material to combustion, impinging said gaseous material against said probe, and detecting the increased rate of vaporization of said metallic material as an indication of the presence of said compound, said increased rate of vaporization of the metallic material being detected by a flame ionization detector technique including monitoring the electrical conductivity of a flame which receives the vaporized metallic material released from said probe.

9. A process in accordance with claim 8 wherein the combusted gaseous material is used to heat said probe.

10. A process in accordance with claim 8 wherein said gaseous material originally includes a mixture of organic compounds free of said element, only one of said organic compounds having a functional group replaceable by said element, further including reacting the original gaseous material with a reagent including said element to produce a derivative of said one organic compound including said element before subjecting said gaseous material to combustion, whereby the presence of said one organic compound in said original gaseous material is confirmed.

11. A process in accordance with claim 8 wherein said gaseous material is subjected to combustion by an additional flame including a gas selected from the group consisting of hydrogen and carbon monoxide, further including separately monitoring the electrical conductivity of said additional flame.

12. A process in accordance with claim 11 wherein said additional flame is confined in a lower chamber and said first-mentioned flame is confined in an upper chamber, said probe being positioned below said firstmentioned flame and in the path of the combusted gaseous material from said additional flame, said vaporized metallic material diflusing upwardly from said probe to be received by said first-mentioned flame.

13. A process in accordance with claim 12 further including interposing an electrostatic shield between said lower and upper chambers to facilitate separately monitoring the electrical conductivities of said first-mentioned flame and said additional flame.

14. A process in accordance with claim 13 wherein said electrostatic shield defines said probe by including said metallic material.

15. A process for detecting the presence in a gaseous material of a compound having an element selected from the group consisting of halogens and phosphorus comprising providing a probe including a metallic material which vaporizes at an increased rate when heated in the presence of said element, said metallic material being selected from the group consisting of alkali metals, barium, strontium, calcium and mixtures of the same, heating said probe, impinging said gaseous material against said probe, and detecting the increased rate of vaporization of said metallic material as in indication of the presence of said compound, said increased rate of vaporization of said metallic material being detected by a flame photometry detector technique.

16. A device for detecting the presence in a gaseous material of a compound having an element selected from the group consisting of halogens and phosphorus comprising a probe including a metallic material which vaporizes at an increased rate when heated in the presence of said element, said metallic material being selected from the group consisting of alkali metals, barium, strontium, calcium and mixtures of the same, means for heating said probe, means defining a source of said gaseous material, means for impinging said gaseous material from said source against said probe, and means for detecting the increased rate of vaporization of said metallic material as an indication of the presence of said compound, said means for detecting said increased rate of vaporization of said metallic material including flame ionization detector means, said flame ionization detector means including a burner device having a flame positioned to receive the vaporized metallic material released from said probe, means for supplying a gas selected from the group consisting of hydrogen and carbon monoxide to said flame, and means for monitoring the electrical conductivity of said flame.

17. A device in accordance with claim 16 wherein said metallic material is in a form selected from the group consisting of a substantially pure metallic material, a metallic amalgam, a metallic salt and mixtures of the same.

18. A device in accordance with claim 16 wherein said probe integrally includes said metallic material.

19. A device in accordance with claim 16 wherein said probe includes an inert, heat-resisting base material coated by a layer including said metallic material.

20. A device for detecting the presence in a gaseous material of a compound having an element selected from the group consisting of halogens and phosphorus comprising a probe including a metallic materlal WhlCl'l vaporizes at an increased rate when heated in the presence of said element, said metallic material being selected from group consisting of alkali metals, barium, strontium, calcium and mixtures of the same, means for heatlng said probe, means defining a source of said gaseous material, means for combusting said gaseous material, means for impinging said gaseous material from said source against said probe, and means for detecting the increased rate of vaporization of said metallic material as an 1nd1- cation of the presence of said compound, said means for detecting the increased rate of vaporization of said metallic material including flame ionization detector means, said flame ionization detector means including a burner device having a flame positioned to receive the vaporized metallic material released from said probe, means for supplying a gas selected from the group consisting of hydrogen and carbon monoxide to said flame, and means for monitoring the electrical conductivity of said flame.

21. A device in accordance with claim 20 wherein said means for monitoring the electrical conductivity of said flame includes a ring electrode circumscribing said flame, and a housing enclosing said flame and said ring electrode, said housing being grounded.

22. A device in accordance with claim 20 wherein said means for combusting said gaseous material includes an additional flame ionization detector means, said additional flame ionization detector means including an additional burner device having a flame, means for supplying a gas selected from the group consisting of hydrogen and carbon monoxide to said flame of said additional burner device, and means for monitoring the electrical conductivity of said flame of said additional burner device, said last-mentioned means being separate from said means for monitoring said flame of said first-mentioned burner device.

23. A device in accordance with claim 22 further including means defining a lower chamber confining said flame of said additional burner device, means defining an upper chamber confining said flame of said first-mentioned burner device, means supporting said probe below said flame of said first-mentioned burner device and in the path of the combusted gaseous material from said flame of said additional burner device whereby said combusted gaseous material is said means for heating said probe and whereby said vaporized metallic material diffuses upwardly from said probe to be received by said flame of said first-mentioned burner device.

24. A device in accordance with claim 23 further including an electrostatic shield interposed between said upper and lower chambers to facilitate separately monitoring the electrical conductivities of said flame of said first-mentioned burner device and said flame of said additional burner device.

25. A device in accordance with claim 24 wherein said electrostatic shield includes said metallic material thereby defining said probe.

26. A device in accordance with claim 25 wherein said means defining said upper and lower chambers includes upper and lower portions, respectively, of a continuously extending housing, said electrostatic shield comprising a foraminous electrically conductive member extending substantially completely across said housing intermediate said upper and lower portions.

27. A device in accordance with claim 26 wherein said housing is grounded, further including a ring electrode circumscribing said flame of said first-mentioned burner device and an additional ring electrode circumscribing said flame of said additional burner device.

28. A device in accordance with claim 26 wherein said foraminous member is a removably carried screen.

29. A device in accordance with claim 28 wherein said upper portion of said housing includes a vented removable cover member allowing access to said screen and escape of gaseous material diffusing upwardly from said flame of said first-mentioned burner device.

30. A device for detecting the presence in a gaseous material of a compound having an element selected from the group consisting of halogens and phosphorus comprising a probe including a metallic material which vaporizes at an increased rate when heated in the presence of said element, said metallic material being selected from the group consisting of alkali metals, barium, strontium, calcium and mixtures of the same, means for heating said probe, means defining a source of said gaseous material, means for impinging said gaseous material from said source against said probe, and means for detecting the increased rate of vaporization of said metallic material as an indication of the presence of said compound, said means defining said source of gaseous material including a gas chromatography column.

References Cited UNITED STATES PATENTS 1/1957 Anthes 23232 XR 6/1962 McWilliam.

MORRIS O. WOLK, Primary Examiner.

R. M. REESE, Assistant Examiner.

US. Cl. X.R. 23254; 73-23.1

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