Determination of fluoroquinolones in aquaculture products by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of fluoroquinolones-ciprofloxacin (CIPRO), danofloxacin (DANO), enrofloxacin (ENRO) and sarafloxacin (SARA)-in aquaculture products, specifically salmon, shrimp and tilapia. After initial sample extraction with an acidic acetonitrile solution, the extract was diluted with dichloromethane and centrifuged, then an aliquot was concentrated and applied to a C18 solid-phase extraction cartridge and concentrated for a second time. The resultant residue was dissolved in acetonitrile, diluted with water, and then further defatted with hexane. The fluoroquinolone residues were determined by UPLC with an HSS T3 C18 reverse-phase column using an ammonium hydroxide-formic acid buffer in an acetonitrile gradient with MS/MS detection using multiple reaction monitoring. Average recoveries for salmon tissue ranged from 73% for DANO to 95% for SARA, for shrimp from 71% for DANO to 109% for SARA, and from 62% for DANO to 111% for SARA in tilapia, fortified at the 1.0 ng g(-1) level. Standard curves were linear between 0.002 and 0.5 ng injected for all compounds. Detection limits of 0.2 ng g(-1) for CIPRO, DANO, ENRO, and SARA were easily obtainable. The operational errors, interferences, and recoveries for fortified samples demonstrate that this described method is suitable for routine use in a regulatory programme. The recommended method is simple, rapid, specific and reliable for the routine monitoring of fluoroquinolone residues in aquatic species such as salmon, tilapia and shrimp.

Simultaneous determination of emamectin and ivermectin residues in Atlantic salmon muscle by liquid chromatography with fluorescence detection.

A liquid chromatographic (LC) method for determining residues of the antiparasitic drugs emamectin (EMA) and ivermectin (IVR) in fish tissues has been developed. EMA and IVR residues are extracted with acetonitrile and cleaned up on a C18 solid-phase extraction column. Extracts are derivatized with 1-methylimidazole and trifluoroacetic anhydride and the components are determined by LC on a C18 reversed-phase column with fluorescence detection (excitation: 365 nm, emission: 470 nm). The mobile phase is 94% acetonitrile-water run isocratically. Calibration curves were linear between 1 and 32 ng injected for both EMA and IVR. The limit of detection for both analytes was 0.5 ng/g, with a limit of quantitation of 1.5 ng/g. Recoveries of EMA and IVR added to salmon muscle averaged 96 +/- 9% and 86 +/- 6%, respectively, at levels between 5 and 80 ng/g. The percent relative standard deviation for the described method was less than 7% over the range of concentrations studied. The operational errors, interferences, and recoveries for fortified samples compare favorably with an established IVR method. The recommended method is simple, rapid, and specific for monitoring residues of EMA and IVR in Atlantic salmon muscle.