Simultaneous Determination of Nine Plant Growth Regulators in Navel Oranges by Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry

A new and reliable method for the simultaneous determination of nine plant growth regulators in navel oranges was developed by liquid chromatography-triple quadrupole tandem mass (QqQ LC/MS). Extraction was performed by acetone and ethyl acetate (v/v, 1:2) with microwave-assisted extraction technique. Cleanup of extracts was performed with dispersive-solid phase extraction (d-SPE) using active carbon as the sorbent. The identification of each analyte was established by chromatographic retention time, analyte-specific fragmentation patterns, and relative peak area ratios of precursor/production pairs. Under the optimized conditions, the average recoveries (six replicates), except for methyl naphthacetate, were in the range of 61.0-109.4 % and limits of detection ranging from 0.01 to 162.2 mu g kg(-1). The results demonstrated that the developed QqQ LC/MS, extraction and purification method is highly effective for analyzing trace amounts of target plant growth regulators (PGRs) in navel orange samples.