A simple and high-throughput method of ultrasonic extraction-capillary electrophoresis for determination of melamine in milk

Abstract

A simple, rapid, sensitive, and low cost method of ultrasonic extraction (USE) and capillary electrophoresis (CE) for the determination of melamine in milk is developed. The most widely used extraction methods of melamine (SPE and LLE) were compared with ultrasonic-assisted extraction by evaluating simplicity, cost and sample clean-up effect, and the conditions of CE were optimized. The melamine was extracted by acetonitrile under the action of ultrasonic energy. After centrifuging, diluting and filtering, the extract was analyzed by CE directly. The determination used 20 mM NaH₂PO₄ as running buffer (pH 2.6), UV detection at 208 nm, and an applied voltage of 18 kV. The proposed method demonstrated good performance concerning linearity (R² = 0.9989), precision (2.6–4.8%), limit of detection and quantification (LOD, 0.163 mg kg⁻¹; LOQ, 0.542 mg kg⁻¹) and accuracy (85.1–98.3%). The proposed method is rapid, convenient and low-cost for the determination of melamine in milk products.