Development of an analytical method for guazatine pesticides in agricultural products using LC-MS/MS

Guazatine, a non-invasive disinfectant used for seed treatment and post-harvest citrus protection, inhibits bacterial lipid synthesis and consists of about 13 components. While it may occasionally be detected in fruits and vegetables such as citrus, its use as a pesticide has been banned in several countries due to health and environmental concerns. To ensure safe export of domestic produce, a simultaneous method of analysis for guazatine components was developed, focusing on GG, GGG, GGN, and GNG as indicators. Using LC-MS/MS, samples were extracted with a 3% formic acid/acetone mixture and purified with hexane. The method was validated across five agricultural products (mandarin, pepper, potato, brown rice, and soybean), achieving an r² above 0.995, and detection and quantitation limits of 0.8 and 2.5 µg/L, respectively. Ion suppression was high, with matrix effects ranging from -84.2 to -89.8%. Recovery rates were 70.2-99.6%, with relative standard deviations under 6.8%. Cross-laboratory validation showed recovery rates of 70.3-106.7% and relative standard deviations below 15.0%, meeting CODEX guidelines.