A simple multi-residue method for determination of plant growth retardants in Ophiopogon japonicus and soil using ultra-performance liquid chromatography-tandem mass spectrometry.

Plant growth retardants may play an important role in regulation of yield and quality of crops, fruits, and vegetables. Such compounds have begun to be used in the cultivation of traditional Chinese medicines (TCMs), especially for root medicines. Although the potential risks to human health of these compounds has attracted increasing attention, analytical methods for detection of plant growth retardants in TCMs remain poorly investigated. In this study, an effective and reliable method for simultaneous determination of 11 plant growth retardants in Ophiopogon japonicus and soil samples was developed by ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry (UPLC-QqQ-MS/MS). Extraction was conducted in acetonitrile containing 1.0% (v/v) acetic acid with ultrasonication. The octadecylsilyl (C18) and MgSO4 were used as the dispersive-solid phase extraction (d-SPE) sorbent and provided satisfactory recoveries for the analytes. The conditions of extraction and LC-MS/MS were optimized to achieve the highest recovery and sensitivity. Good linearity was achieved within a wide range with all correlation coefficients exceeding 0.9950. The recoveries of all analytes in O. japonicus and soil samples ranged from 57.37% (choline chloride) to 99.93% (trinexapac-ethyl) and from 54.37% (daminozide) to 94.82% (triadimenol), respectively. The limits of quantifications ranged from 0.03 to 3.54 μg/L. The proposed method was successfully applied to detect and quantify 11 plant growth retardants in empirical O. japonicus and soil samples. High frequency of paclobutrazol and choline chloride was found in O. japonicus samples. In addition, paclobutrazol showed a high residual concentration (>1100 μg/kg) in the soil of O. japonicus indigenous production.