Identification of sulfur compounds

A summary of the work on the identification of sulfur compounds in crude oils has been given recently by Ball, Rail, Waddington, and Smith (31), who list the sulfur compounds isolated from petroleum by earlier investigators and, in addition, give several new compounds which have recently been isolated from a Wasson, Tex., crude petroleum by the API Research Project 48. Birch and Norris (5) isolated a substantial number of the thiol (mercaptan) type of sulfur compounds from an Iranian crude petroleum. 

A number of reviews related to the identification of sulfur compounds in petroleum should be mentioned. Dean and Whitehead (30) summarized work on separation and identification of sulfur compounds in petroleum and shale oil in 1967. Drushel (7) reviewed sulfur compound types with an emphasis on the available analytical methods as of 1970. Mehmet (31) and Gal pern (32) also reviewed sulfur compounds in petroleum in 1971 with some speculation on their origin. The major contributions of API Project 48 reported by Coleman et al. in 1971, Rail et al. in 1972, and Thompson in 1981 will be discussed below (33-35) More recent summaries of sulfur compounds by Aksenov and Kamyanov in 1981 (36) and by Gal pern in 1985 (37), discuss OSC in petroleum, processed petroleum fractions, shale oil, coal derived liquids and related products. These reviews include much of the Soviet literature. In 1975 and 1978 Orr (28-291 discussed sulfur in the petroleum system with somewhat... 

Qualitative Analysis. High-resolution MS generally can separate and identify the formulas of essentially all heteroaromatic components containing one or more oxygen, sulfur, and nitrogen atoms per molecule, although some difficulties remain in the routine identification of sulfur compounds. The approach used to compensate for the latter difficulty is discussed in the section on quantitative analysis. 

API and Bureau of Mines Projects. Some of the most important current work on the sulfur compounds present in petroleum is being carried out under the auspices of the American Petroleum Institute under Project 48 which was organized in 1948 to conduct fundamental studies on the synthesis, properties, and identification of sulfur compounds in petroleum. At present. Project 48 consists essentially of four phases (1) production and purification of sulfur compounds and the determination of their common physical properties (2) measurement of thermodynamic properties of pure sulfur compounds (3) identification and measurement of sulfur compounds in crude oil and (4) development of methods of synthesis and identification of sulfur compounds. Work on the first three phases, combined as Project 48A, is being conducted at the U. S. Bureau of Mines under the supervision of H. M. Smith as project director. Work on the fourth... 

Properties, and Identification of Sulfur Compounds in Petroleum. A Report on API Research Project 48, Preprint of paper presented at the 32nd Annual Meeting of API, Chicago, Ill., Nov. 10, 1952. 

Organic sulfur compounds are present in gasoline and diesel. With the increased emphasis on the requirement for more environmentally friendly transportation fuels [1], oxidative desulfurization, using H202 and redox-molecular sieves [2,5,6,7], has been studied and shown to significantly reduce the sulfur content of gasoline and diesel. The reaction of thiophene and its derivatives were successfully converted to oxidized compounds, but the identification of oxidized compounds was not simple because the concentrations of individual sulfur compounds were low. Most of the previous literature has reported sulfone formation. 

Although the mass spectra of dibenzothiophene, its sulfoxide, and its sulfone have been recorded, the bulk of published work in this area is mainly of a general nature concerned with the identification of types and classes of sulfur compounds. As a result, detailed fragmentation patterns of dibenzothiophene derivatives are few in number. Mass spectrometry, particularly low electron voltage mass spectrometry, has, however, been extensively used for the identification of dibenzothio-phenes in petroleum. ... 

Surface Chemical Analysis. Electron spectroscopy of chemical analysis (ESCA) has been the most useful technique for the identification of chemical compounds present on the surface of a composite sample of atmospheric particles. The most prominent examples Include the determination of the surface chemical states of S and N in aerosols, and the investigation of the catalytic role of soot in heterogeneous reactions involving gaseous SO2, NO, or NH3 (15, 39-41). It is apparent from these and other studies that most aerosol sulfur is in the form of sulfate, while most nitrogen is present as the ammonium ion. A substantial quantity of amine nitrogen also has been observed using ESCA (15, 39, 41). 

This work has demonstrated that organically bound sulfur forms can be distinguished and in some manner quantified directly in model compound mixtures, and in petroleum and coal. The use of third derivatives of the XANES spectra was the critical factor in allowing this analysis. The tentative quantitative identifications of sulfur forms appear to be consistent with the chemical behavior of the petroleum and coal samples. XANES and XPS analyses of the same samples show the same trends in relative levels of sulfide and thiophenic forms, but with significant numerical differences. This reflects the fact that use of both XPS and XANES methods for quantitative determinations of sulfur forms are in an early development stage. Work is currently in progress to resolve issues of thickness effects for XANES spectra and to define the possible interferences from pyritic sulfur in both approaches. In addition these techniques are being extended to other nonvolatile and solid hydrocarbon materials. 

Elemental composition C 15.77%, S 84.23% carbon disulfide. It may be analyzed by GC using a sulfur chemiluminescence detector or by GC/MS. A concentration of 1 ppm in the air may be measured by mass spectrometry. The primary characteristic ionic mass for identification of this compound by mass spectrometry is 76. Many GC columns are available commercially. 

The FPD detector is quite specific for sulfur compounds and enhances the signal several fold over the FID. The total ion current chromatogram of these same sulfur standards were run with capillary GC on a Finnegan ITD. The mass spectral identification of each compound was quite efficient with the ITD system, even at 25 nanograms sample per peak. 

Unnatural Products Chemistry. The complete identification of unknown compounds that we have successfully resolved using PB/LC/MS will clearly require additional analytical information, such as provided via liquid chromatography ICP/MS (detecting nonmetals such as chlorine and sulfur), FT-IR, UV or proton and heteroatom NMR. This situation is analogous to that of a natural products chemist faced with making a complete structural assignment of an unknown compound isolated from some matrix such as seaweed instead of a leachate from a hazardous waste site. The natural products chemist would exploit the complete array of analytical instrumentation and not attempt identification based solely upon low resolution (quadrupole) mass spectrometry. 

Identification, Analysis, and Nomenclature of Sulfur Compound Types... 

Liquids Some, but not all components of Sulfur/Arsenical Vesicants can be detected by M8 paper. All components of Sulfur/Arsenical Vesicants can be detected by M9 papers. The APD 2000 provides semi-quantitative identification of sulfur mustard/Lewisite mixtures. Colorimetric tubes are available which can detect thioethers, organic arsenic compounds as well as arsine (AsHg). Detection with PIDs or PIDs may be possible. Detection and identification with FT-IR is possible provided that the appropriate reference spectra are available. 

The minute quantities of sulfur compounds found in many foods makes their analysis and quantitation a challenging problem. Extraction without further fractionation, will, in many cases, not result in a high enough concentration of these trace sulfur constituents to permit their identification by gas chromatogra-... 

The aim of this research is to utilize the SCD to detect the sulfur compounds found in UHT processed milk. An integrated analytical approach to sampling, detection, and identification is used which includes purge and trap volatile concentration followed by thermal desorption, GC separation, SCD detection, and mass spectral identification. The sulfur compounds identified should be chiefly responsible for the cooked flavor in UHT milk. In addition, the mechanism for the disappearance of this sulfurous flavor will be explored. 

A qualitative test for aromatic and heteroaromatic compounds is their solubility in concentrated sulfuric acid (Shriner, R. L. Fuson, R. C. and Curtin, D. Y. The Systematic Identification of Organic Compounds Wiley New York, 1956. Another precedent is the H-D exchange of thiophene by dissolving the latter in concentrated D2SO4. 

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