Pipetting sample preparation with water eluent followed by water mobile phase HPLC analysis for residual monitoring of melamine in milk

The author introduces a small-scale, time shortening, economical sample preparation with water eluent followed by an isocratic water phase HPLC system for quantifying melamine in cow’s milk. Sample preparation is achieved by homogenization using a handheld ultrasonic-homogenizer with water followed by MonoTipⓇC18 pipette tip contains silica monolith bonded with octadecyl group with water eluent. For determination and identification of analyte, the HPLC uses an analytical C18 column, an isocratic 100% water, and a photo-diode array detector. The procedure, performed under a 100% water conditions, uses no organic solvents and poisonous reagents at all and is, therefore, harmless to both humans and the environment. The method validation data were well within the international method acceptance criteria. The total analytical time and quantitation limit were < 6 min/sample and 0.24 μg/mL, respectively. The present technique may be proposed as an international harmonized analytical method for routine residue monitoring for melamine in milk.