Quantitation in gradient high performance liquid chromatography/inductively coupled plasma mass spectrometry investigated using diclofenac and chlorpromazine

The use of directly coupled high performance liquid chromatography/inductively coupled plasma mass spectroscopy (HPLC/ICPMS) employing chlorine (35Cl/37Cl) detection has been investigated with respect to the detection and quantitation of the drugs diclofenac and chlorpromazine. By integration of peak areas in the ‘chloratogram’ (the chlorine-specific HPLC chromatogram), a calibration curve was constructed, from which the concentrations could be determined. Chlorine-detected HPLC/ICPMS is quantitative over a wide range of concentrations of pharmaceutical relevance for metabolite detection and the results reproducible (standard deviation ± 0.43%) over multiple injections. Application of gradient chromatography and variation in the bulk mobile phase physicochemical properties has little effect on the ICPMS detection response for these compounds. This work indicates that the use of HPLC/ICPMS is likely to be quantitatively reliable for metabolism studies for a range of chlorinated xenobiotics.