The determination of antimicrobials in aquaculture fish is important to ensure food safety. Therefore, simple and fast multiresidue methods are needed. A liquid chromatography tandem mass spectrometry method was developed and validated for the quantification of 14 antimicrobials (quinolones and tetracyclines) in fish. Antimicrobials were extracted with trichloroacetic acid and chromatographic separation was achieved with a C18 column and gradient elution (water and acetonitrile). The method was validated (Decision 2002/657/EC) and it was fit for the purpose. Linearities were established in the matrix and the coefficients of determination were ≥0.98. The method was applied to Nile tilapia and rainbow trout (n = 29) and 14% of them contained enrofloxacin at levels above the limit of quantification (12.53-19.01 µg.kg) but below the maximum residue limit (100 µg.kg). Even though prohibited in Brazil and other countries, this antimicrobial reached fish. Measures are needed to ascertain the source of this compound to warrant human safety.

The present study sought to develop lipid bases from blends between patawa oil and palm stearin. These blends were analyzed before and after the chemical interesterification process for their fatty acid and triacylglycerol composition, free fatty acid (FFA) content, peroxide index, thermal properties, melting point, consistency, and solid fat content (SFC). Blends with unsaturated fatty acid contents between 60 and 70% were obtained, with a good ratio between saturated and unsaturated fatty acids, which indicates a healthy content of fatty acids. Variations in the triacylglycerol contents and melting and crystallization thermograms evidenced the reaction. The blend with 50% stearin and 50% patawa oil showed the best results after the chemical interesterification reaction regarding the possible application in fatty products for its appropriate melting point, SFC similar to that of soft table margarines, plastic and spreadable consistency at refrigeration temperature, thus combining physical and nutritional properties desirable for the food industry.

The objective of this study was to develop and validate a fast, sensitive and simple liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method for the screening of six classes of antibiotics (aminoglycosides, beta-lactams, macrolides, quinolones, sulfonamides and tetracyclines) in fish. Samples were extracted with trichloroacetic acid. LC separation was achieved on a Zorbax Eclipse XDB C18 column and gradient elution using 0.1% heptafluorobutyric acid in water and acetonitrile as mobile phase. Analysis was carried out in multiple reaction monitoring mode via electrospray interface operated in the positive ionization mode, with sulfaphenazole as internal standard. The method was suitable for routine screening purposes of 40 antibiotics, according to EC Guidelines for the Validation of Screening Methods for Residues of Veterinary Medicines, taking into consideration threshold value, cut-off factor, detection capability, limit of detection, sensitivity and specificity. Real fish samples (n=193) from aquaculture were analyzed and 15% were positive for enrofloxacin (quinolone), one of them at a higher concentration than the level of interest (50µgkg), suggesting possible contamination or illegal use of that antibiotic.

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