Surface Desorption Atmospheric Pressure Chemical Ionization Mass Spectrometry for Detection of Melamine in Kidney Stone Samples

The clinical human kidney stone samples that generated no satisfactory signal in direct analysis using surface desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS) were dissolved in acetic acid/methanol solutions, and then deposited on a paper surface for DAPCI-MS analysis without desalination. The results showed that the melamine and the uric acid as well, in the stone samples were rapidly detected and identified by using DAPCI-MS2. The detection limits were about 3.4 x 10(-15) g/mm(2) for melamine on the paper surface. The analytical results obtained using DAPCI-MS were validated by using conventional ESI-MS. The data demonstrate that DAPCI-MS2 is a promising technique for clinical diagnosis of nephrolithiasis caused by either melamine or uric acid, particularly because of its high specificity, high throughput and good accuracy.