Simultaneous determination of lactic acid and pyruvic acid in tissue and cell culture media by gas chromatography after in situ derivatization-ultrasound-assisted emulsification microextraction.

Lactic acid and pyruvic acid are important metabolites in the tricarboxylic acid cycle that can reflect the cytoplasmic redox state and mitochondrial respiratory chain function. The combination of these acids is considered as a screening index for mitochondrial disorders. Due to their biological effects, a derivatization method was developed to simultaneously detect pyruvic acid and lactic acid in tissue and cell culture media using gas chromatography. In this work, the combined derivatization method with methoxyamine hydrochloride and isobutyl chloroformate was first proposed. To improve the efficiency of derivatization, in situ derivatization-ultrasound-assisted emulsification microextraction (USAEME) was used in this study. After optimizing the volume of reagents and reaction times, good linearity values were obtained from 50 to 1000 μmol/L and 1 to 100 μmol/L for lactic acid and pyruvic acid, respectively. The limits of detection (LODs) were 0.12 μmol/L for lactic acid and 0.29 μmol/L for pyruvic acid. The recoveries of the two analytes were between 93.60 and 102.80%, and the precisions were less than 6.20%. This method was successfully applied to quantify pyruvic acid and lactic acid in the animal and cellular hypoxia models which provided an auxiliary means for the diagnosis of mitochondrial diseases. Graphical abstract ᅟ.