Concurrent Lactic and Volatile Fatty Acid Analysis of Microbial Fermentation Samples by Gas Chromatography with Heat...

Area of Science:

• Analytical Chemistry
• Biochemistry
• Environmental Science

Background:

• Gas chromatography (GC) is effective for volatile organic acid analysis.
• Lactic acid, a crucial fermentation product, is non-volatile and difficult to quantify by standard GC.
• Previous methods using periodic acid for lactic acid oxidation to acetaldehyde yielded inconsistent GC results.

Purpose of the Study:

• To develop an improved GC method for accurate lactic acid quantification.
• To overcome issues of inconsistent peak generation in prior lactic acid analysis.
• To enable simultaneous analysis of multiple organic acids in biological samples.

Main Methods:

• A heat-treated derivatization pre-treatment was employed for lactic acid analysis.
• Samples were mixed with periodic acid and heated in sealed tubes at 100°C for 45 minutes.
• The method was validated for reproducible acetaldehyde peak generation prior to GC injection.

Main Results:

• The new method produced reproducible and consistent acetaldehyde peaks.
• This approach enabled accurate lactic acid quantification, independent of GC injector parameters.
• Simultaneous determination of other organic acids like acetone, ethanol, and volatile fatty acids was achieved.

Conclusions:

• The developed heat-treated derivatization method significantly improves lactic acid analysis by GC.
• This technique offers precise and convenient organic acid profiling for fermentation and anaerobic digestion samples.
• The method enhances the utility of GC for comprehensive analysis of biological samples.