Simultaneous enantioselective determination of triazole fungicides in soil and water by chiral liquid chromatography/tandem mass spectrometry.

The manuscript concerns the development and validation of a novel and sensitive multi-residue method for simultaneous enantiomeric analysis of 8 triazole fungicides (tetraconazole, fenbuconazole, epoxiconazole, diniconazole, hexaconazole, triadimefon, paclobutrazol, and myclobutanil) in soil and water using chiral liquid chromatography coupled with tandem mass spectrometry. The separation and determination were performed using reversed-phase chromatography on a cellulose chiral stationary phase, a Chiralcel OD-RH (150 mm × 4.6 mm) column, under isocratic conditions using a mixture of ACN-2 mM ammonium acetate in water (55/45, v/v) as the mobile phase at 0.45 mL/min flow rate. The effects of three cellulose-based columns and three amylose-based columns on the separation were also investigated. The QuEChERS (acronym for quick, easy, cheap, effective, rugged and safe) method and solid-phase extraction (SPE) were used for the extraction and clean-up of the soil and water samples, respectively. Parameters including the matrix effect, linearity, precision, accuracy and stability were undertaken. Under optimal conditions, the mean recoveries for all sixteen enantiomers from the soil samples were 76.4-108.1% with 2.6-12.0% intra-day relative standard deviations (RSD) and 4.2-14.1% inter-day RSD at 5, 25 and 50 μg/kg levels; the mean enantiomer recoveries from the water samples were 81.2-106.5% with 2.1-11.5% intra-day RSD and 3.4-13.6% inter-day RSD at 0.25, 0.5 and 2.5 μg/L levels. Coefficients of determination R2 ≥ 0.9989 were achieved for all studied analytes in the soil and water matrix calibration curves within the range of 1.0-125 μg/L. The limits of detection (LOD) (S/N=3) for all enantiomers in the soil and water were less than 1.0 μg/kg or μg/L, whereas the limit of quantification (LOQ) (S/N=10) did not exceed 3.0 μg/kg or μg/L. The results of the method validation confirm that this proposed method is convenient and reliable for the enantioselective determination of the enantiomers of triazole fungicides in soil and water.