A Method to Assess Glyphosate, Aminomethylphosphonic Acid and Glufosinate in Chinese Herb Samples Using a Derivatization Method and LC-MS/MS

An effective analytical method to quantify glyphosate (Gly), aminomethylphosphonic acid (AMPA) and glufosinate (Glu) in four kinds of Chinese herbs by derivatization was developed. The method was studied in four steps: extraction, purification, derivatization and enrichment. The extraction and purification steps were optimized. The sample was added with isotope-labeled internal standards and extracted with 30% acetonitrile. The MCX solid-phase extraction cartridge was chosen to reduce interferences and the purification solution was derivatized with 9-fluoromethoxycarbonyl chloride. 4 M HCl was selected as reaction terminator. The supernatant was enriched by salting-out using NaCl and analyzed by LC-MS/MS in heated positive electrospray ionization mode by multiple reactions monitoring. To verify the method methodically, matrix effect, linearity, limits of quantitation and detection, accuracy and precision all met SANTE/12682/2019 requirements. The modified method was applied to 152 batches of 4 different Chinese herbs. The overall detection rate of Gly was 79.61%, AMPA was 72.37% and Glu was 16.45%.