Abstract:

A method using liquid-phase microextraction coupled to high performance liquid chromatography (LPME-HPLC) was proposed for the determination of melamine in dairy products. LPME was achieved with polypropylene hollow fiber for 30 min at 1000 r/min string rate using tributyl phosphate (TBP) as extraction solvent and 0.02 mol/L ammonium sulfate solution at pH 5.0 (pH 8.0 of donor phase) as acceptor phase. An Agilent C18 (4.6 mm × 250 mm, 5μm) column was used for chromatographic separation and the analyte was detected under optimized conditions. The proposed method provided a linear range of 0.01－100 μg/mL with R2 ＝ 0.9987, detection limit of 2.5 ng/mL (RSN = 3), RSD＜4.4% (n = 5) and spike recovery ranging 92.1%－ 102.4%. Less than 34 min is needed for single sample analysis with little organic solvent consumption. Moreover, this method has the advantages of high sensitivity and extraction efficient and good reliability, thereby benefiting the rapid determination of low content of melamine in complex dairy product matrices.

Key words: liquid-phase microextraction, high performance liquid chromatography, melamine, dairy products, rapid determination