R. Hollingsworth, F. Dazzo
Apr 1, 1988
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0
Influential Citations
4
Citations
Journal
Journal of Microbiological Methods
Abstract
Abstract Phenylisocyanate was used to quantitatively esterify the free hydroxyl group of 3-hydroxyalkanoic ester residues in the isolated lipid A moieties of lipopolysaccharide (LPS) isolated from Rhizobium trifolii. These carbamate esters are stable to the usual conditions used to generate methyl esters of fatty acids for GC-MS analysis (methyl iodide or sulphate and base, diazomethane, and methanol and acids). The UV-absorbing properties of the phenyl group was used to readily detect these stable, phenylcarbamate ester derivatives in TLC isolations using fluorescent silica layers (254 nm) and HPLC isolations using UV detection. The molecular weights (and hence the chain lenghts) of the phenylcarbamate derivatized 3-hydroxy fatty acid methyl esters can be readily obtained from the electron impact mass spectrum of the derivatized compounds even when material is limiting or background is high. The derivatives are very amenable to GC-MS analysis and have retention times which are slightly shorter than the corresponding 3-hydroxy compound on SP2100 DOH. This derivative is useful in determining which 3-hydroxy fatty acids in bacterial LPS are linked through the 3-hydroxyl group and allows, by the use of an electron capture detector, the GC identification of trace amounts of hydroxy acids in the presence of larger proportions of other fatty acids.