HPLC Determination of Melamine in Dairy Products and Feed with Molecularly Imprinted Solid Phase Extraction

Melamine was used as pattern plate in the preparation of melamine moleculary imprinted polymer (MIP), which was packed into the self-made funnel-like solid phase extraction (SPE) micro-column, to form a MIP-SPE microcolumn having selective adsorptive property toward melamine. 10 mL of the sample solution was passed through the micro column at a flow-rate of 0.5 mL·min-1. After rinsing the column with 5 mL each of H2O and mixture of CH3OH and H2O(1+1) in succession, the column was eluted with 8 mL of mixture of CH3OH and aq. NH3(95+5), and the eluate was evaporated to dryness by N2-blowing. The residue was dissolved with 1.00 mL of CH3OH, which was used for HPLC analysis. LC separation was performed by using Inertsil ODS-SP C18 column as stationary phase, and using a mixture of (A) mixed solution of 10 mmol·L-1 sodium octane sulfonate and 10 mmol·L-1 citric acid (pH 3.0) and (B) acetonitrile (mixed in the volumic ratio of 90+10) as mobile phase. UV-detection at 240 nm was adopted in the determination. Recovery was tested by standard addition method at 3 concentration levels, values of recovery found were ranged from 89.0% to 97.0%.