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A C18 column packed with core-shell particles was used for the chromatographic separation of sulphonamides in feed and meat by a conventional high performance liquid chromatography system coupled with a diode array detector. Two analytical methods, already used in our laboratory, have been modified without any changes in the extraction and clean-up steps and in the liquid chromatography instrumentation. Chromatographic conditions applied on a traditional 5-μm column have been optimized on a column packed with 2.6 μm core-shell particles. A binary mobile phase [acetate buffer solution at pH 4.50 and a mixture of methanol acetonitrile 50: 50 (v/v)] was employed in gradient mode at the flow rate of 1.2 mL with an injection volume of 6 μL. These chromatographic conditions allow the separation of 13 sulphonamides with an entire run of 13 minutes. Preliminary studies have been carried out comparing blanks and spiked samples of feed and meat. A good resolution and the absence of interferences were achieved in chromatograms for both matrices. Since no change was made to the sample preparation, the optimized method does not require a complete revalidation and can be used to make routine analysis faster. [ABSTRACT FROM AUTHOR]

A simple, sensitive and selective multiresidue high-performance liquid chromatography with diode array detection method for determination of 13 sulphonamides in eggs was developed and validated. Sample extraction and clean-up conditions were carefully studied and factors as gradient elution and column temperature were found as key parameters to improve separation efficiency. The method was validated following the European Commission Decision 2002/657/EC criteria adopting spiking levels of 20, 40 and 60 μg kg −1 “As Low As Reasonably Achievable”. The necessary requirements for precision (RSD R % below 23%) and trueness (recovery ranging from 45.2% to 87.5%) were fulfilled. Decision limit (CCα) values below 18.5 μg kg −1 , comparable to those reported in LC-MS detection, demonstrated the suitability of the method in residues surveillance plans for the sulphonamides analysis in eggs at the carry-over level without the use of sophisticated and expensive instrumentation. [ABSTRACT FROM AUTHOR]

In the present study, a column packed with core-shell particles was used for the separation and the quantification of 13 sulphonamides in milk by conventional high-performance liquid chromatography coupled with diode array ultraviolet detection (HPLC/UV-DAD). Preliminary experiments were carried out to investigate selectivity of different stationary phases. Best results were achieved using a C 18 column packed with 2.6 μm core-shell particles (diameter 4.6 mm, length 75 mm). A binary gradient elution based on acetate buffer solution at pH 4.50 and a mixture of methanol acetonitrile 50:50 (v/v) was employed at the flow rate of 1.2 mL min −1 with an injection volume of 6 μL. These chromatographic conditions allowed the efficient separation of 13 sulphonamides in about 8 min. To evaluate the suitability of the method for official control analysis, the most important validation parameters were investigated according to the European Decision 657/2002/EC as established for analysis of drug residues in food. Sulphonamides were recovered from milk samples by a simple and quick preparation procedure consisting of an extraction step with chloroform/acetone and a purification step with n -hexane. Mean recoveries from raw milk ranged between 55% and 86% at the Maximum Residual Limit of 100 μg kg −1 , and RSDs% resulted lower than Thompson and Horwitz RSD% reference values for all sulphonamides. The LOQ value (2.7–15 μg kg −1 ) was low enough to satisfy legal limits suggested by European Regulation 37/2010/EC. [ABSTRACT FROM AUTHOR]