Determination of Melamine in Dairy Products, Fish Feed, and Fish by Capillary Zone Electrophoresis with Diode Array Detection

This paper describes an approach to determine melamine (MEL) in liquid milk, yogurt, whole milk powder, fish feed, and fish at residue levels using capillary zone electrophoresis with diode array detection (CZE-DAD) for the first time. Suspicious samples were extracted with 1% trichloroacetic acid while 1 mL of chloroform was used to precipitate fat in the real samples. After centrifuging and filtering, the extract was analyzed by CZE-DAD directly. By investigating the variables of extraction, separation, and detection in detail, the entire analytical procedure including sample preparation could be completed within 30 min. The limits of detection and quantitation for MEL were found to be 0.01 and 0.05 mu g mL(-1), respectively. The proposed method was successfully applied for the analysis of MEL in dairy products, fish feed, and fish with total recoveries ranging from 93 to 104%.