SRM-MS Analysis of CPZ Uptake in Cells

Standards and metabolite extracts from cells were resuspended in methanol and processed using the previously described LC gradient on the Micro200 LC instrument coupled with the 5600+ TripleTOF mass spectrometer. The ion source nebulizer gas and heater gas were set at 18 psi, and the curtain gas was set at 20 psi. The ion spray voltage was set at 5000 V with a DP set at 100. A TOF scan was performed over the mass range of 100–500 Da. A product ion scan of 279.18 was collected over a range of 50–300 Da using a CE of 25 V. The extracted ion chromatogram (XIC) of the m/z 279.18 → m/z 139.09 transition and the MS/MS fragmentation pattern were both used to verify the identity of CPZ. A standard curve based on peak height versus concentration of the CPZ standards was constructed for quantification.