Organic sulfur compounds determinations

FCC feedstocks contain sulfur in the form of organic-sulfur compounds such as mercaptan, sulfide, and thiophenes. Frequently, as the residue content of crude oil increases, so does the sulfur content (Table 2-5). Total sulfur in FCC feed is determined by the wavelength dispersive x-ray fluorescence spectrometry method (ASTM D-2622), The results are expressed as elemental sulfur. 

SFC-FID is widely used for the analysis of (nonvolatile) textile finish components. An application of SFC in fuel product analysis is the determination of lubricating oil additives, which consist of complex mixtures of compounds such as zinc dialkylthiophosphates, organic sulfur compounds (e.g. nonylphenyl sulfides), hindered phenols (e.g. 2,6-di-f-butyl-4-methylphenol), hindered amines (e.g. dioctyldiphenylamines) and surfactants (sulfonic acid salts). Classical TLC, SEC and LC analysis are not satisfactory here because of the complexity of such mixtures of compounds, while their lability precludes GC determination. Both cSFC and pSFC enable analysis of most of these chemical classes [305]. Rather few examples have been reported of thermally unstable compounds analysed by SFC an example of thermally labile polymer additives are fire retardants [360]. pSFC has been used for the separation of a mixture of methylvinylsilicones and peroxides (thermally labile analytes) [361]. 

Hence, CSV can be viewed as the mirror image of ASV. CSV is best suited for the determination of inorganic anions (e.g., halides, cyanide) or organic sulfur compounds (e.g., penicillins, thiols) that form insoluble salts with the electrode material. In addition to mercury, silver electrodes may be advantageous for the determination of anions that form insoluble silver salts. 

Ogata, M., Fujisawa, K., 1990. Gas chromatographic and capillary gas chromatographic/ mass spectrometric determination of organic sulfur compounds in sediment from ports significance of these compounds as an oil pollution index. Bull. Environ. Contam. Toxicol. 44, 884-891. 

Randt, C. and R. Altenbeck. 1997. Problems in the development of a method for the determination of the total amount of adsorbable organic sulfur compounds (AOS) in water/wastewater. Vom Wasser 88 217-225. 

Binde, F. and H.H. Riittinger. 1997. Isolation and determination of dissolved organic sulfur compounds— development of the organic group parameter DOS. Fresenius J. Anal. Chem. 357 411—415. 

The formation of organic sulfur compounds in salt marsh porewaters is not as well understood(H) as the inorganic moieties although progress has been made in coastal marine sediments(12). Their presence as thiols and alkyl sulfides has been determined but generally in trace amounts(12-16). The importance of these trace organic sulfur compounds to atmospheric sulfur emissions is presently an area of intense research(, 15). Less appears to be known about organic sulfur compounds in salt marsh porewaters. 

Organic sulfur compounds (e.g., mercaptans, sulfides, polysulfides, thiophenes) are present in petroleum products to a greater or lesser extent depending on the crude oil origin and the refinery treatment. The sulfur content of fuel oil (ASTM D-396) can be determined by a variety of methods (ASTM D-129,ASTM D-1552, ASTM D-2622, ASTM D-4294, IP 61, IP 63), with mercaptan sulfur in cracked stocks being particularly necessary for evaluation (ASTM D-3227, IP 342). 

The products from cumene hydroperoxide decomposition induced by organic sulfur compounds were determined by quantitative NMR except for phenol by high-pressure liquid chromatography and cumene hydroperoxide by iodometric titration (16). Cumyl alcohol is produced in the initial oxidation of sulfenic acid to sulfonic acid, and subsequently most of it is converted to a-methylstyrene as shown in Table II. The major products (40-45%) are phenol and acetone consistent with an acid-catalyzed decomposition of cumene hydroperoxide. Considerable... 

The monitoring of the emission of organic sulfur compounds Determining the potential formation of metabolites to predict possible risks Product development, process monitoring, and quality control to minimize toxic, harmful, and dangerous products and byproducts. 

Such sorbents are mainly used for the extraction of organic sulfur compounds from organic solvents. Extensive determinations have been applied to extract and separate thiophenes, disulfides, mercaptanes, and polycyclic aromatic sulfur hydrocarbons (PASHs) from oils and fuels, as well as to separate PAHs and PASHs. 

The stereochemistry of organic sulfur compounds was reviewed very extensively by Laur in 1972 and that of organic polysulfides by Rahman et in 1970. Since those days, however, considerable progress has been made. The molecular and crystal-structures of more than 60 cyclic and acyclic polysulfanes of type R-S -R have been determined by X-ray diffraction on single crystals. In rare cases, electron diffraction of the vapor of R-S -R molecules has been used to determine the structure (see Diffiaction Methods in Inorganic Chemistry). In addition, the structures of several acyclic polysulfane oxides such as RS-SO-SR and RS02-S -S02R (n = 1, 2, 3), and of the trisulfane cation (MeS)3+, have been determined. 

Florence TM (1979) Cathodic stripping voltammetry. Part I. Determination of organic sulfur compounds, flavins and porphyrins at the sub-micromolar level. Journal of Electroanalytical Chemistry 97 219-236. 

Well over 100 compounds have been determined in seawater (and sediments) using a considerable variety of techniques (Table 2). Methods include n-and branched alkanes (up to about C20, pristane/ phytane), alkenes and aromatic compounds (up to the disubstituted naphthalenes), halocarbons and chlorinated aromatic species, low relative molecular mass alcohols, organic sulfur compounds (notably dimethyl sulfide, a major product of some phytoplankton species, but ranging up to dimethyl trisulfide), and freons (11, 12, and 113 used in studies of oceanic mixing). 

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