Multiresidue Method for Quantification of Nitroimidazoles, Anthelmintics, Amphenicols, and Dyes in Meat, Shrimp, and Fish by Using a Modified QuEChERS-type Extraction and Isotope Dilution Ultra-High Performance Liquid Chromatography-Tandem Mass Spect

This paper presents an analytical multiresidue method for the quantification of 7 nitroimidazoles, 19 anthelmintics, 3 amphenicols, and 4 dyes in poultry, pork, beef, horse, shrimp, and fish samples by isotope dilution ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) in a single 6 min run. Samples were prepared using a modified quick, easy, cheap, effective, rugged and safe (QuEChERS)-type extraction with ethyl acetate and Na2SO4-NaCl (2:1), concentration into dimethyl sulfoxide (DMSO), and defatting by liquid-liquid extraction (LLE) with n-hexane. No clean-up using solid-phase extraction (SPE) cartridges or dispersive solid-phase extraction (DSPE) was necessary. The linearity ranges (in μg kg−1) were 0.10-0.60 for chloramphenicol, 0.50-3.0 for dyes, 1.5-9.0 for nitroimidazoles, and 5.0-30.0 for the other drugs. The limits of quantitation (LOQ) were established at the lowest calibration curve levels. Except for chloramphenicol in the horse matrix, analyte recovery and reproducibility were satisfactory (recovery (fREC): 75.0 to 116.6%; coefficient of variation (CV): 1.2 to 29.9%). For the unapproved substances and the substances with a maximum residue level (MRL), respectively, the decision limits (CCα) were 0.14-4.10 and 5.28-1003.60 μg kg−1, while the detection capabilities (CCβ) were 0.13-3.33 and 5.46-11.56 μg kg−1.