Analysis of organic acids in high-temperature Daqu based on UPLC-MS/MS technology

A method for simultaneous determination of 11 organic acids (citric acid, isocitric acid, tartaric acid, succinic acid, malic acid, malonic acid, lactic acid, adipic acid, maleic acid, fumaric acid and ascorbic acid) in high-temperature Daqu was established using ultra-high performance liquid chromatography triple quadrupole tandem mass spectrometry (UPLC-MS/MS). The high-temperature Daqu sample was extracted and diluted with water, separated by Accucore aQ chromatography column (150 mm×2.1 mm, 2.6 μm), eluted with a gradient of methanol-0.2% formic acid water as the mobile phase at a flow rate of 400 μl/min and column temperature of 40 ℃, determined by negative ion multiple reaction monitoring mode (MRM), and quantified by the matrix external standard method. The results showed that the 11 organic acids had good linear relationships within their respective mass concentration ranges, with correlation coefficients R²≥0.996, the detection limit (LOD) were 0.08-4.13 μg/kg, the quantification limit (LOQ) were 0.27-13.76 μg/kg, the average recovery rates were 77.0%-113.0%, and the relative standard deviation (RSD) of precision tests results were 0.1%-11.5%. This method had simple pretreatment, short analysis time, high accuracy, and good repeatability, which was suitable for analyzing the contents of 11 organic acids in high-temperature Daqu samples.