Short-chain sulfonates

House and Darragh determined short-chain sulfonates by ultraviolet absorption in acidic solution after removal of the long-chain sulfonates by ether extraction. 

For sufficient retention of these very polar sulfonated carboxylates on RP columns, the addition of an ion-pairing (IP) agent such as tetraethylammonium acetate (TEAA) to the LC buffer was compulsory [13]. To maintain the compatibility of the eluent with the MS interface, the use of such an involatile cationic additive entailed a cation exchanger to be placed between the column and the interface [13]. Alternatively, equimolar amounts (5 mM) of acetic acid and triethyl-amine, which form the volatile IP agent triethylammonium, were added to the mobile phase in order to improve the retardation of very polar SPC [14]. While the first approach with TEAA was effective in retaining even the very short-chain C3- and C4-SPC (Fig. 2.10.4), the weaker IP agent triethylammonium notably increased the retention of C5-SPC and higher, whereas C4-SPC elutes almost with the dead volume of the LC (Fig. 2.10.5). Addition of commonly used ammonium acetate as buffer component led to the co-elution of the short-chain SPC ([Pg.322]

As expected, LC separation of the dichloromethane/acetone SPE eluate in the RP-mode, presented as FIA-APCI-MS(+) in Fig. 2.12.13, was impossible because the alkyl ethoxy amines as cationic surfactants could not be eluted under conventional RP-separation conditions [37, 53]. The use of methane sulfonic acid for ion-pairing resulted in the separation of the compounds in the methanol eluate as shown as TIC (d) and selected ion trace masses (m/z 504 (a), 670 (b), and 802 (c)) in Fig. 2.12.14. Here, the short-chain ethoxy amines were eluted later than the more polar long-chain homologues [39]. 

In contrast to the other large cats, the urine of the cheetah, A. jubatus, is practically odorless to the human nose. An analysis of the organic material from cheetah urine showed that diglycerides, triglycerides, and free sterols are possibly present in the urine and that it contains some of the C2-C8 fatty acids [95], while aldehydes and ketones that are prominent in tiger and leopard urine [96] are absent from cheetah urine. A recent study [97] of the chemical composition of the urine of cheetah in their natural habitat and in captivity has shown that volatile hydrocarbons, aldehydes, saturated and unsaturated cyclic and acyclic ketones, carboxylic acids and short-chain ethers are compound classes represented in minute quantities by more than one member in the urine of this animal. Traces of 2-acetylfuran, acetaldehyde diethyl acetal, ethyl acetate, dimethyl sulfone, formanilide, and larger quantities of urea and elemental sulfur were also present in the urine of this animal. Sulfur was found in all the urine samples collected from male cheetah in captivity in South Africa and from wild cheetah in Namibia. Only one organosulfur compound, dimethyl disulfide, is present in the urine at such a low concentration that it is not detectable by humans [97]. 

The hydrotropes in this era were short chain aromatic sulfonates, with the p-xylene sodium sulfonate as a typical example. Their action is preventing the formation of liquid crystals is easily understood from a direct comparison of their molecular geometry (Fig. 1). 

The lability of organic S to oxidation and recycling is not understood. Short-chain thiols appear to be dynamically cycled in marine and saltmarsh sediments (120, 211). In contrast, sulfones may represent a stable oxidized product that could provide a useful signature of sediment oxygenation (121, 184). Sulfones have been identified in saltmarsh and ancient marine sediments (32, 207). Other (unidentified) forms of organic S appear to yield acidity and sulfate upon oxidation (38, 192). Much more research is needed to elucidate the mechanisms of organic S fonnation and the relationships between specific organic S compounds and lake conditions. 

Sulfonates include alkylbenzenesufonates (ABS), the most widely used of the non-soap surfactants short-chain alkylarenesuifonates lig-nosulfoliates napllialenesulfoliates cz-olefinsulfonales petroleum sulfonates sulfonates with ester, amide, and ether linkages and fatty acid ester sulfonates. 

The latexes investigated were the 357 nm Dow monodisperse polystyrene (LS-1010) and two polydisperse polystyrene latexes prepared in our laboratory (2) where the concentration of functional monomer, Cops II (Alcolac-ammonium salt of a short chain vinyl sulfonate), added to the recipe was 10 3 and 10 -M for and C, respectively. 

Short-chain ion-pairing reagents, e.g., hexane sulfonic acid, have been used in HPLC for protein and peptide separations. This reagent can also be used in CE for hydrophobic peptides that are difficult to separate. 

Aliphatic hydrocarbons include straight chain and branched structures. Industrial solvents, petroleum hydrocarbons, and the linear alkyl benzene sulfonates (LAS) are the primary sources of aliphatic hydrocarbon pollutants. Many microorganisms utilize aliphatic hydrocarbons as carbon sources. Long-chain -alkanes are utilized more slowly due to the low bioavailability that results from their extremely low solubility in water. In contrast, short-chain rc-alkanes show a higher aqueous solubility. 

Mixed Carboxylate-Sulfonate Systems. Decanolc and octanoic acids were selected as carboxylic acids in view of their intermediate chain lengths. Some initial experiments using a short-chain carboxylic acid (isobutyric acid) were not very promising, apparently because only a fraction of the acid would partition to the drop surface. 

---