Isotopic internal standard correction for the determination of diludine residue in animal-derived matrix samples using enhanced matrix removal-lipid clean-up combined with ultra-performance liquid chromatography-tandem mass spectrometry

Abstract

A robust method has been established for the successfully determination of diludine (DHP) levels in animal-derived matrix samples, utilizing enhanced matrix removal-lipid clean-up (EMR-lipid) combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS). DHP-13C4 was employed as an isotopically labeled internal standard to estimate the recovery, matrix effect, and process efficiency. The water-acetonitrile mixture was utilized to extract the edible tissues (muscle, fat, kidney, and liver) of cattle and chicken, while the salting out method was employed for extracting egg and milk. The extracts were then mixed with water and acetonitrile to a constant volume, and subjected to clean-up via cartridge. Subsequently, the analytes were transferred onto a reversed-phase C18 analytical column and quantified by triple-quadrupole tandem mass spectrometry in multiple-reaction monitoring mode. Quantification was accomplished using a solvent calibration curve in conjunction with an internal standard method. The proposed method showed good linearity in the range of 0.5–50 ng mL−1 (R2 ≥ 0.999), high sensitivity (the limit of detection was 2.5 μg kg−1, and the limit of quantification was 5 μg kg−1), a high spiked recovery rate (between 82.6% and 109.4%), and repeatability (the relative deviation within the batch and the relative deviation between batches were ≤ 7.5%).