Determination of Formetanate Hydrochloride in Agricultural Products by LC-MS/MS

An analytical method based on LC-MS/MS was developed for the determination of formetanate hydrochloride in agricultural products. Formetanate hydrochloride was confirmed to be stable in acetonitrile. It was therefore extracted from samples with acetonitrile, and the crude extracts were purified using a combination of ethylenediamine-N-propyl silylation silica gel and graphite carbon mini columns. Formetanate hydrochloride in the resulting sample solutions was quantified by LC-MS/MS utilizing an external solvent calibration curve. The average recovery (n=5) of formetanate hydrochloride spiked in 10 types of agricultural products (brown rice, soybean, spinach, cabbage, potato, apple, orange, lime, nectarine and green tea) at the maximum residue limits (MRLs) or at a uniform limit of 0.01 mg/kg was 92.3-103%, with a relative standard deviation of 1.3-5.4%. The limit of quantitation of the developed method was calculated to be 0.01 mg/kg.