Optimization of a modified QuEChERS method for the determination of tetracyclines in fish muscle by UHPLC-MS/MS

In this work a sample treatment based on a modified QuEChERS method combined with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was proposed to determine the residues of five common tetracyclines in fish muscle samples. The separation was achieved in less than 4 min and the analytes were detected in electrospray ionization in positive mode (ESI+) with multiple reaction monitoring mode. Parameters affecting the extraction step, such as the amount of sample and EDTA-Mcllvaine buffer and extraction solvent volumes, were optimized by means of experimental design. In order to obtain the lowest matrix effect, parameters affecting the clean-up step by dispersive solid phase extraction (dSPE), were also studied. Under optimum conditions, matrix effect was lower than vertical bar 15 vertical bar% in all cases. Limits of quantification were lower than 4.4 mu g kg(-1) for the compounds in the selected samples, being in compliance with the current legislation. The precision, expressed as relative standard deviation, was below 18.5% and the recoveries for fortified fish samples (salmon and panga) higher than 80%. These results revealed that the proposed method is simple, rapid, cheap and environmentally friendly, being successfully applicable for the determination of these residues in fish samples. (C) 2018 Elsevier B.V. All rights reserved.