Improvement of gas chromatographic analysis for organic acids and solvents in acetone-butanolethanol fermentation from sweet sorghum juice

Abstract

Modern development for gas chromatographic peak recognition of organic acids and organic solvents in acetone-butanol-ethanol (ABE) fermentation was investigated under different temperature programmes. Either propanol or iso-butanol was used as an internal standard. The results showed that short retention time and fair recognition peak of the compounds were obtained under the following column temperature programme: 10 min at 150°C, 15°C/min to 180°C and 20 min at 180°C. The appearance of the chromatograms showed that iso-butanol allowed higher resolution and satisfactory peak shape for the tested compounds than propanol. Calibration curve between ratios of standard peak area per internal standard peak area and concentrations of the organic acids and organic solvents under these conditions had a good linear correlation with R² ≥ 0.998. When ABE fermentation by Clostridium beijerinckii JCM1390 from sweet sorghum juice was carried out in a 2-L fermenter, the highest butanol concentration was 7.56 g/l with the butanol yield of 0.33 g/g sugar utilized.

Key words: Acetone-butanol-ethanol fermentation, column temperature programme, gas chromatography, sweet sorghum juice.