New capillary electrophoresis method for the determination of furosine in dairy products.

A new capillary electrophoresis (CE) method was established for the quantitative determination of furosine in dairy products. Sample preparation and suitable electrophoretic conditions allowed accurate and reproducible quantitation of furosine in dairy products. Sample preparation consisted of drying hydrolyzed samples, redissolving them in 0.2 M NaOH, and purifying them by solid-phase extraction. The electrophoretic separation was carried out in an uncoated capillary maintained at 30 degrees C using 0.1 M phosphate buffer containing the additive hexadecyl trimethylammonium bromide (HDTAB, 1.2 mM) (pH 7.0) under 10 kV voltage and reverse polarity. Coefficients of variation of less than 2.25% for migration time and 5.80% for peak areas indicated that the technique was reproducible. The calibration curve followed a linear relationship with a highly significant (p < 0.01) coefficient of multiple determination (R (2) = 0.997). The limit of quantitation was 0.5 ppm, a concentration that corresponds to 4.5 mg/100 g of protein in milk samples. Furosine concentration (mg/100 g of protein) ranges of different dairy products (raw, pasteurized, UHT, and evaporated milks and yogurt) agreed with ranges previously reported. Therefore, the CE method presented is a suitable technique for the routine assessment of furosine in dairy products.