Analysis of chlormequat chloride and mepiquat chloride residues in tomato, tomato paste and pear by using liquid chromatography-tandem mass spectrometry

A rapid method for analyzing the two plant growth regulators chlormequat chloride and mepiquat chloride residues in tomato, tomato paste and pear by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. The samples were extracted with V (water):V (acetonitrile)=1:1. Special clean-up procedures such as enrichment or concentration were not necessary. The chromatographic separation was carried out by HILIC column. Analytes were detected by electro-spray ionization (ESI+), and multiple reaction monitoring (MRM) mode. Quantification was performed by peak area external standard methods using matrix-matched calibration curves, which were linear in the range of 0.001-0.02 mg/L with good linear relationships. The correlation coefficients were all above 0.999. In the case of tomato, tomato paste and pear, the limits of detection (LOD) for chlormequat chloride and mepiquat chloride were estimated in the range of 0.0004-0.002, 0.0009-0.002 mg/kg, respectively. And the limits of quantification (LOQ) were both validated as 0.01 mg/kg. At 0.01, 0.02 and 0.05 mg/kg spiked levels, the recoveries and the relative standard deviations (RSD) was 71%-94%, 75%-101% and 1.9%-7.7%, 2.8%-6.9% for chlormequat chloride, and mepiquat chloride. Finally, this method was simple, quick, accurate, and could be applied to the determination of chlormequat chloride and mepiquat chloride residues in tomato, tomato paste and pear.