Surface Desorption Atmospheric Pressure Chemical Ionization Mass Spectrometry for Direct Detection Melamine in Powdered Milk Products

A novel method was developed for the direct detection of trace amounts of melamine in powdered milk products by using surface desorption atmospheric pressure chemical ionization mass spectrometry(SDAPCI-MS) without any sample pretreat ment.Taking the advantage of multiple-stage tandem MS capability of an ion trap mass analyzer,all the signals detected from milk powders were quickly identified using the characteristic fragments of melamine,resulting in confident validation of the analytical results.The average time for a single sample analysis was less than 0.5 min;the speed was largely determined by the sample loading which took more than 29 s for each manual delivery.The recoveries for five samples spiked with 1-5 mg/kg melamine were 86.7%-112.8%,and the relative standard deviations of the method were 4.3%-10.3%.The limit of determination of this method was found to be 8.8 μg/kg.The data show SDAPCI-MSn is a powerful tool for rapid,semi-quantitative detection of melamine in food products.