Multi-residue analysis of plant growth regulators and pesticides in traditional Chinese medicines by high-performance liquid chromatography coupled with tandem mass spectrometry.

A multi-residue method was developed for the simultaneous determination of 24 plant growth regulators (PGRs) and 11 representative pesticides that were widely applied in plants used in traditional Chinese medicines (TCMs) by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The method was validated taking into consideration EU guidelines; calibration curves for all of the targeted analytes showed correlation coefficients (γ2) higher than 0.9901. The limits of detection (LOD) ranged from 0.2 to 8 µg/kg. The average recovery for all analytes in spiked samples ranged from 63.18 to 127.23%, with a relative standard deviation of ≤ 15%. The proposed method has been applied to 480 batches of TCM samples, including 34 species of medicinal plants, from the TCM market. The results showed that 14 PGRs and 5 pesticides were detected, including choline chloride, chlormequat, paclobutrazol, uniconazole, phoxim, etc. Among them, there were high detection rates for chlormequat (40%), choline chloride (100%), atonik (73.75%), abscisic acid (80.83%), and indole-3-acetic acid (41.25%). The residual level of paclobutrazol in Ophiopogonis radix exceeded the recommended maximum residue limits (MRLs) according to GB 2763-2016. In addition, 14 agrochemicals used in TCM planting were collected and detected; the result showed various PGRs were detected in samples registered as fertilizer. These results indicate that PGRs and pesticides were widely used in the cultivation of medicinal plants, especially for radix and rhizome herbs. The residue of targeted PGRs and pesticides in TCM samples from this study have a high frequency and high level. Graphical abstract.