G. A. Silva
Aug 1, 1995
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Journal
Applied Microbiology and Biotechnology
Abstract
The use of butanoic, pentanoic and hexanoic acids as internal standards for chromatographic analysis of complex mixtures of by-products from acidic fermentation, produced by Bacillus stearothermophilus grown in xylose-containing medium, was evaluated. After addition of the internal standards, the aqueous supernatant microbial fermentation fluids were submitted to the derivatisation process with methanol and sulphuric acid at 50° C. Injection of 1-μl aliquots of the lower chloroform layer was carried out. The esterified compounds were separated in approximately 14 min by temperature programming on a glass column packed with 10% (w/w) diethyleneglycol adipate and 2% phosphoric acid, and analysed with a flame ionisation detector. Chromatograms of the methyl esters derivates have shown that both pentanoic and hexanoic acids can be used as internal standards for gas-chromatographic analysis of acidic fermentation end-products, since they are well separated and resolved. Under the experimental conditioss established, the methyl ester of butanoic acid was masked by the chloroform peak and so is not a convenient compound for further use.