Meng Chen

The widespread environmental dissemination of imidazole compounds necessitates robust analytical monitoring tools. This study developed a novel isotope-labeled surrogate-based high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) method for the simultaneous determination of 21 imidazoles in water, sediment, and soil. The optimized SPE protocol using Oasis HLB cartridges achieved high recoveries, with chromatographic separation completed in 25 min. Six isotope-labeled standards effectively corrected matrix effects (−57% to 8%), yielding MQLs < 1.0 ng·L⁻¹ (water) and 0.995), accuracy (60–120% recovery for 20/21 analytes), and precision (relative standard deviation, RSD < 15%). Its application in Jiulong River revealed significant contamination, detecting eight imidazoles in both water (up to 49.29 ng·L⁻¹) and sediment (up to 24.01 μg·kg⁻¹). This standardized tool enables routine monitoring of pharmaceutical residues across environmental compartments, supporting regulatory frameworks.

Hundreds of veterinary drugs are widely used in agricultural activities and continuously enter aquatic environments through various pathways, posing potential risks to ecosystem. Considering that sediments function both as sinks and sources of these contaminants, it is crucial to promptly and accurately acquire veterinary drug residue level in sediments. In this study, a highly effective analytical method for simultaneous determination of 103 veterinary drugs from 16 classes in sediments was developed using high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS). The extraction procedure was performed twice by ultrasound-assisted extraction with an acetonitrile-buffer mixture consisting of Na₂EDTA, Na₃PO₄·12H₂O, and Na₃C₆H₅O₇·2H₂O. The supernatant was cleaned using 500 mg/6 mL Oasis HLB solid-phase cartridges. The elution solutions were concentrated and redissolved in formic acid–methanol–water (0.1/20/79.9, v/v, FA-MeOH-H₂O) for detection. Results showed that all 103 target drugs exhibited good linearity with R² > 0.990 over a concentration range of 0.010 to 1000 μg·L⁻¹, and method detection limits (MDLs) ranged from 0.025 to 5 μg·kg⁻¹. The recoveries at three spiking levels (2, 5, and 10 times of the method quantification limits, MQLs) varied from 33% to 150%, 32% to 140%, and 40% to 140%, respectively, with relative standard deviations (RSDs, n = 3) of 0.7%~29%, 0.8%~23%, and 0.5%~20%. The matrix effects for all compounds ranged from –85% to 84% with 32 targets negligible, 51 moderate, and 20 significant. An isotope-labeled surrogate method was proposed for quantitation to effectively overcome matrix effects and improve accuracy with better recoveries of 60%~120% for 93 target drugs and RSDs (n = 3) all below 20%. This method was applied to determine 12 sediment samples collected from the Jiulong River, and 16 target drugs were detected in the concentrations range of 0.1~7.6 μg·kg⁻¹. The method is accurate, sensitive, and efficient, providing a powerful analytical tool for behavior and effect studies of multi-classed veterinary drug residue in sediment environments.

The purpose of this study was to develop and validate a simple, fast, and specific extraction method for the analysis of 64 antibiotics from nine classes (including sulfonamides, quinolones, tetracyclines, macrolides, lincosamide, nitrofurans, β-lactams, nitromidazoles, and cloramphenicols) in chicken eggs. Briefly, egg samples were simply extracted with a mixture of acetonitrile–water (90:10, v/v) and 0.1 mol·L^–1 Na₂EDTA solution assisted with ultrasonic. The extract was centrifuged, condensed, and directly analyzed on a liquid chromatography coupled to tandem mass spectrometry. Compared with conventional cleanup methods (passing through solid phase extract cartridges), the established method demonstrated comparable efficiencies in eliminating matrix effects and higher or equivalent recoveries for most of the target compounds. Typical validation parameters including specificity, linearity, matrix effect, limits of detection (LODs) and quantification (LOQs), the decision limit, detection capability, trueness, and precision were evaluated. The recoveries of target compounds ranged from 70.8% to 116.1% at three spiking levels (5, 20, and 50 μg·kg^–1), with relative standard deviations less than 14%. LODs and LOQs were in the ranges of 0.005–2.00 μg·kg^–1 and 0.015–6.00 μg·kg^–1 for all of the antibiotics, respectively. A total of five antibiotics were successfully detected in 22 commercial eggs from local markets. This work suggests that the method is suitable for the analysis of multiclass antibiotics in eggs.