During the synthesis of ketamine, some inorganic elements might be present in wastewater. The determination of these elements provides useful information for investigation of illegal manufacturing site of ketamine. In this study, an analytical method for simultaneous determination of 8 inorganic elements namely Br, I, P, Mn, Al, Pd, Zn, Cu at trace level using inductively coupled plasma-mass spectrometry (ICP-MS). Validation results revealed high repeatability, good recovery (82.2 to 101.6%), good linearity (correlation coefficients of 0.996 – 1.000) within investigated range of 0.9 ppb to 55.5 ppb, and high sensitivity with limit of quantitation (LOQ) of 0.2 ppb to 16.0 ppb for element.