Rapid determination of volatile organic acids in edible salt and high-salinity food by direct analysis in real time mass spectrometry

Abstract

A simple method based on direct analysis in real time combined with quadrupole time-of-flight mass spectrometry was developed to determine five volatile organic acids (i.e., butyric acid, isovaleric acid, cyclopentanecarboxylic acid, isocaproic acid and cyclohexanecarboxylic acid). Various samples relative to organic acids were investigated, including 45 edible salts and 18 high-salinity foods (curing food, marinated meat and sauce). These volatile organic acids obtained good linearity results (R2 > 0.9907) in the range of 0.5–50 μg/mL. The limits of detection were 0.4–1.0 μg/g, and the limits of quantification were 0.9–3.1 μg/g. The process efficiency of five organic acids were ranging between 81 and 114%. Taking advantage of the salt-tolerant characteristic of DART, the sample preparation process could be simpler than traditional method. Only a few minutes were required owning to the absence of liquid chromatography. As the results of real sample screening, butyric acid, isovaleric acid and cyclopentanecarboxylic acid were found in 15 commercial samples, including 13 edible salts and 2 high-salinity foods.