Abstract:

A method was established for determining plant growth regulator residues in grains by ultra performance liquid
chromatography-tandem mass spectrometry (UPLC-MS/MS). Samples were extracted with methanol-water (90:10, V/V), and cleaned
up on a WAX cartridge. The target analytes were separated on a Waters C18 column with gradient elution using a mobile
phase made up of acetonitrile and 2 mmol/L ammonium formate. Detection was carried out using negative electrospray
ionization and multiple reaction monitoring (MRM), and the external standard method was used for quantification. In the
linear range 5–150 μg/L, the correlation coefficient was larger than 0.9995 for each plant growth regulator. The limits of
detection (LOD) were 0.5–1.5 μg/kg, and the limits of quantitation (LOQ) were 1.5–5.0 μg/kg. The spiked recovery rates at
three levels of 5.0, 10.0 μg/kg and 25.0 μg/kg were in the range of 70.4%–119.0%. The relative standard deviation (RSD)
of intra-day and inter-day assays was 1.68%–8.25%. The method proved to be simple, sensitive, rapid and suitable for the
determination of plant growth regulator residues in grains.

Key words: ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS), plant growth regulator, residue, grains