Determination of Thirty-five Veterinary Drug Residues in Black Chicken by Modified QuEChERS-Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry

In this study, a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method with using a reduced graphene oxide-modified melamine sponge (r-GO@MeS) as matrix purification material was developed for the determination of 35 veterinary drug residues in black chicken meat by ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). First of all, the effects of metal chelating agents (Na₂EDTA), dehydrating agents (MgSO₄, Na₂SO₄) and acetic acid (HAc) addition (0%, 0.5%, 1%, 3%, 5%) on the extraction efficiency of veterinary drugs were thoroughly studied. According to the results, most of quinolones tended to chelate with magnesium ions, resulting in low recoveries of veterinary drugs in the extraction solution, while the appropriate addition of Na₂EDTA and HAc could improve the overall drug recoveries. Therefore, 2.5 mL of 0.1 mmol/L Na₂EDTA aqueous solution and 10 mL of 0.5% HAc-ACN were used as extraction solvents, with 2.0 g of anhydrous Na₂SO₄ and 0.5 g of NaCl as dehydrating agents. Then the effects of sponge dosages (sponge volume/extract volume of 0.45, 0.60, 0.75, 0.90, 1.05 cm³/mL) and different purification modes (dynamic cycles of 1, 5, 10, static time of 1, 5, 10 min) on the purification efficiency were investigated in terms of veterinary drug recoveries. The results showed that a moderate dosage of 0.75 cm3/mL and fast ten dynamic purification cycles tended to give out more acceptable recoveries for all drugs. The method validation results showed that the recoveries of all monitored drug were obtained in the range of 66.6%-118.8% with three different spiked levels of 50, 100, 150 μg/kg. The intra- and inter-day precisions were evaluated in terms of relative standard deviations (RSDs) by repeatability tests conducted on the same day or three consecutive days, which were acquired less than 13.8% and 14.6%, respectively. In the range of 5-200 μg/kg, good linearities were acquired with the correlation coefficients (R²) no less than 0.998. Additionally, the limits of detection (LODs) and quantitation (LOQs) were obtained in the range of 0.1-6 μg/kg and 0.3-15 μg/kg, respectively. By construction of matrix-matched curves and solvent curves, the matrix effect was calculated as -19.4%-19.8%, demonstrating an insignificant matrix effect by using the developed r-GO@MeS materials. Comparatively, the developed r-GO@MeS has the same or even better matrix purification effect as the other three commercial adsorption materials, such as PSA, GCB, C18. Furthermore, the purification process was achieved within several seconds by the quick and convenient soaking-squeezing cycles, and the matrix separation need no extra measures such as high-speed centrifugation and strong magnetic field assistance. This method has the advantages of speed, convenience and low cost, and shows great potential in the field of multi-residue detection of veterinary drugs.