US005424217A United States Patent [19] [11] Patent Number: 5,424,217 Benner et al. [45] Date of Patent: Jun. 13, 1995 [54] PROCESS FOR THE DETECTION OF minescence detection", J. of Chromat. Science, vol. 28, SULFUR pp. 24-28 (Jan. 1990). Banner “Development of the sulfur chemiluminescence [75] Inventors: Richard L. Benner, Fairbanks, Ak.; detector", a dissertation present at the U. of Denver, Donald H. Stedman, Denver, Colo. Sep. 1991. [73] Assignee: Sievers Instruments, Inc., Boulder, Primary Examiner-Lyle A. Alexander Colo. Attorney, Agent, or Firm-Beaton & Folsom [21] Appl. No.: 873,402 [57] ABSTRACT [22] Filed: Apr. 24, 1992 A process and apparatus are disclosed for the detection and measurement of sulfur in both organic and inor Related US. Application Data ganic sulfur-containing compounds. The process in cludes admixing a sample including a sulfur-containing [63] Continuation of Ser. No. 275.980, Nov. 25. 1988. compound with oxygen, and then exposing the mixture [51] Int. Cl.6 ........................................... .. G01N 21/76 to a source of combustion causing heat in the presence [52] US. Cl. .................................. .. 436/123; 436/119; of a combustion supporting reducing agent at a combus 436/172; 436/122 tion site. The resulting gaseous combustion products are [58] Field Of Search ............. .. 436/119, 122, 123, 172; vacuum extracted from the combustion site, and then 422/52 directed into a darkened low pressure chamber. The combustion products in the low pressure chamber are [56] References Cited then contacted with ozone, with the result that the U.S. PATENT DOCUMENTS sulfur combustion products are converted to chemilu minescent sulfur dioxide. The emitted chemilumines 4,066,409 l/ 1978 Fine ................................... .. 436/123 4,190,368 2/1980 Etess 422/52 cence is then detected, and may be measured to provide 4,352,779 10/1982 Parks .. .. 436/123 a quantitative indication of the amount of sulfur in the 4,678,756 7/1987 Parks ................................. .. 436/123 original sample. The preferred source of oxygen is air, the preferred form of combustion heat is a flame, and OTHER PUBLICATIONS the preferred form of reducing agent is hydrogen gas. Shearer et 01., “Analysis of sulfur compounds by capil lary column gas chromotography with sulfur chemilu 10 Claims, 2 Drawing Sheets FREON lo MASS TANK FLOW FLOW METER RESTRICTER ROTAMETER {16 I 1 -AIR UPPLY ACTIVATED 4° MASS _5--> CHARCOAL - FLOW ~00 ,4 TRAP " METER ~12 18 FLOW 26 28?l RESTZICTER 202I EXHAUST OZONE-WW WATER TRAP ‘ TRAP RCD FLOW RESTRICTER 1 ROTAMETER .—-oo 24 OZONE , GENEARATOR o2 RECORDER 22 US. Patent June 13, 1995 Sheet 2 0f 2 5,424,217 00 on onow mat A21“:ZOCdéhZmUZOU com 000 com RESPONSE (mV) 5,424,217 1 2 Another approach to measuring sulfur-containing PROCESS FOR THE DETECTION OF SULFUR compounds in a fluid sample including includes the use of chemiluminescence detection schemes. RELATED APPLICATION There remains a need for a process and device capa ble of measuring sulfur compounds accurately, quickly This application is a continuation of Applicant’s co and in the low femtogram range without being sensitive pending US. patent application Ser. No. 07/275,980 to interference of other compounds and components of ?led on Nov. 25, 1988. the sample being tested. BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION a) Field of the Invention In view of the foregoing, it is an object of the present The present invention relates generally to processes invention to provide a process and device for detecting and apparatus for detection and measuring of chemical and measuring sulfur in a ?uid sample, and in particular ly-bound sulfur, and more particularly, to the detection in an environmental air sample or a chromatographic and measurement of sulfur combustion products which eluent. have been contacted by ozone to form chemilumines It is another object of the present invention to pro cent reaction products. The present invention also re vide a process and device for detecting sulfur-contain lates to improved processes and apparatus for enhanc ing compounds in a rapid and continuous manner with ing the chemiluminescent detection of sulfur by the out regard to the presence of other compounds in the reduction of interfering compositions. sample. b) Discussion of the Prior Art A further object of the present invention is to provide Numerous processes and apparatus have been de a novel and improved method and apparatus for mea vised for detecting and measuring chemical substances. surement of sulfur-containing compounds by chemilu Among detectors used to detect and measure ?uids, minescent reaction with ozone at low pressures in such whether from an independent source, or from the out 25 a way as to be sensitive to sulfur compounds, but insen put of a gas chromatographic apparatus, are those using sitive to water vapor, carbon dioxide or other hydrocar thermal conductivity, hydrogen ?ame ionization, elec bon interferences. ' tronic capture, alkaline ?ame ionization, and ?ame pho Accordingly, the present invention discloses and tometry. Of particular interest in recent years has been teaches a process and apparatus for the detection and the sensitive and selected detection of sulfur com measurement of bound sulfur in organic and inorganic pounds, both as a pollutant in the environment, and sulfur containing compounds. The process includes from other sources. The most widely utilized sulfur admixing a fluid sample having a sulfur-containing com selective detector at the present time is the ?ame photo pound with an oxygen source. This mixture is then metric detector (FPD). The FPD device and process is exposed to a combustion causing heat source, such as a based on the fact that a hydrogen ?ame in the presence 35 ?ame, in the presence of a reducing agent. The resulting of air (oxygen) emits electromagnetic radiation, usually gaseous combustion products are then vacuum ex in the form of visible spectra light. In practice, a carrier tracted from the combustion site, and then directed into ?uid transporting a to-be-tested substance, for example a darkened low pressure chamber. The combustion products in the low pressure chamber are then con an eluent separated from a sample by a chromato tacted with ozone, with the result that the sulfur com graphic instrument, is mixed with an air stream (which bustion products are converted to chemiluminescent may be oxygen enriched), and passed onto a hydrogen sulfur dioxide in an excited state. Finally, the chemilu burner, or a burner in the presence of hydrogen. The minescence is detected and measured to provide an resulting mixture contains hydrogen in excess of that indication of the amount of sulfur in the ?uid sample. required for complete combustion of the oxygen pres The preferred source of oxygen is air, the preferred ent. The luminous radiation caused by this combustion form of combustion heat is a ?ame, and the preferred impinges or is re?ected through an optical ?lter which form of reducing agent is hydrogen gas. has been selected according to the desired radiation In one particular preferred embodiment of the inven wavelength of the substance to be measured. Subse tion, a halogenated compound is injected into the sam quently, the light from the ?lter passes to a light detec ple mixture prior to or at the time that it is subjected to tor, such as a photomultiplier tube. The photomultiplier combustion. ~ tube produces a current which can be detected, mea As described in greater detail below, the present sured, analyzed, recorded, and so on, to indicate the invention utilizes a hydrogen-air ?ame to produce a substance and the amount of the substance. Such an combustion product of either sulfur monoxide (S0) or FPD system can be used as a speci?c selective detector hydrogen sul?de (HgS) for subsequent reaction with and process for sulfur in sulfur-containing substances ozone. It should be noted that, because of its thermal since a speci?c wavelength is emitted from the forma instability, ozone cannot be directly introduced at the tion of molecular species of sulfur during the burning of combustion site as a feasible means of exploiting the the hydrogen flame. Such an FPD system is relatively chemiluminescent reaction of ozone with the combus sensitive and has been widely used, for example in pol tion products. Various studies have shown that a signi? lution control and determination. However, the funda cant portion of sulfur entering a ?ame produces sulfur mental response of such FPD detectors to sulfur is not monoxide. In fact, the sulfur monoxide so produced is linear with respect to the concentration of the to be present in the ?ame combustion products in concentra measured sulfur, and are dif?cult to calibrate with accu tions which are about ten times greater than atomic racy, especially for the measurement of low concentra 65 sulfur, which is the substance which is normally mea tions of sulfur. Another distinct problem with FPD sured by conventional FPD processes and apparatus. devices is that numerous other components in the sam However, it is a possibility that the process of the pres ple can interfere with accurate determination of sulfur. ent invention actually produces H25, and then detects 5,424,217 3 4 the chemiluminescent reaction of H28 with ozone. Nev tion chamber 20 from an ozone generator or other ertheless, it is believed that the principle combustion ozone source 22. In reaction chamber 20 ozone is ad product is sulfur monoxide. Regardless of whether S0 mixed and reacted with the gaseous combustion prod or H28 is produced as the combustion product, they ucts from combustion assembly 12. This particular pro both produce approximately the same wavelength of cedure results in the production of chemiluminescent light during the chemiluminescent reaction with ozone.