Multiresidue determination of 21 pharmaceuticals in crayfish (Procambarus clarkii) using enzymatic microwave-assisted liquid extraction and ultrahigh-performance liquid chromatography-triple quadrupole mass spectrometry analysis.

In this paper, a multiresidue enzymatic-microwave assisted extraction prior to ultrahigh performance liquid chromatography and triple quadrupole mass spectrometry analysis has been developed for the determination of 21 pharmaceuticals in crayfish (Procambarus Clarkii) samples. The analysed compounds corresponding to 6 therapeutic families were: fluoroquinolones (ciprofloxacin, danofloxacin, enrofloxacin, flumequine, gatifloxacin, grepafloxacin, marbofloxacin and norfloxacin); tetracyclines (chlortetracycline and oxytetracycline); sulphonamides (sulfamethoxazole, sulfadiazine, sulfamethazine, sulfamerazine); penicillins (amoxicillin); anfenicols (chloramphenicol, thiamphenicol and florfenicol); non-steroidal anti-inflammatory drugs (ibuprofen and salicylic acid) and trimethoprim an antibiotic that is frequently co-administered with sulfamethoxazole. The main factors affecting the extraction efficiency were optimized for 0.5 g of lyophilized tissue. The enzymatic microwave extraction was carried out using an extraction time of 5 min with 5 mL of an acetonitrile: water (1:1, v/v) mixture, 50 μL of Proteinase-K solution and 5 μL of formic acid at 50 W. After centrifugation, the liquid extract was evaporated and the residue was reconstituted with 1 mL of 0.1% (v/v) formic acid. Chromatographic and MS parameters, in both positive and negative ionization modes, were also optimized. The mobile phase used consisted on a mixture of 0.1% (v/v) formic acid aqueous solution and acetonitrile in gradient elution mode at a 0.4 mL min-1 flow rate. The proposed method was validated and recoveries over 70% were obtained for all the analytes with detection limits in the 0.6-12 ng g-1 range. The proposed method was successfully applied to crayfish specimens from Doñana National Park, Spain.