Polar Reversed-Phase Liquid Chromatography Coupled with Triple Quadrupole Mass Spectrometer Method for Simple and Rapid Determination of Maleic Hydrazide Residues in some Fruits and Vegetables

Maleic hydrazide (MH) is used as a plant growth regulator, herbicide, and sprouting inhibitor for some crops to improve the growth and the quality of some fruits and vegetables so that MH residues should be analyzed in food. Most of the chromatographic analysis methods for MH residues were operated by using ion chromatographic (IC) columns which need complicated with extra washing and conditioning steps. The developed method has overcome this problem by using Synergi polar reversed-phase (RP) column and non-scheduled multiple-reactions monitoring (MRM) scanning modes. Liquid chromatography coupled with negative electrospray ionization triple quadrupole mass spectrometer LC-ESI (-) MS/MS method was developed and validated according to SANTE/12682/2019 at four fortification levels in four food matrices. The method optimization was carried out by using different extracting solvents, LC columns, and mobile phase ratios. The extraction was developed and operated by using 1% formic acid in methanol. The limits of quantification (LOQ) for MH were in the range 0.05-0.1 mu g/g that was below the EU maximum residue limit (MRL), set for the studied food matrices such as onion, potatoes, citrus, and grape (15, 50, 0.2, and 0.2 mu g/g) respectively. Good method linearity was obtained in the concentration range 0.01-2 mu g/ml with correlation coefficients (r(2)) >= 0.99. The average recoveries ranged from 84 to 110% with relative standard deviations RSDs <= 17%. The matrix effects on the MH signals were studied and compensated by using the standard addition technique. This polar-RP-LC-ESI (-) MS/MS method was developed to help laboratories which determine the MH residues in food.