Development and Application of Simultaneous Analytical Method for Pharmaceuticals and Metabolites in Environmental Water Samples

It has been recognized in recent years that the occurrence of a wide variety of pharmaceuticals in the aquatic environment is chiefly due to secondary effluent from sewage treatment plants, where the residual pharmaceuticals contained may possibly be in the range of ng·L-1 to μg·L-1. However, little is still known of the occurrence and behavior of pharmaceutical metabolites such as conjugates, epoxides and hydroxides in an aquatic environment. The authors developed an instrumental analytical method with liquid chromatography - tandem mass spectrometry (LC/MS/MS) for the simultaneous determination of three pharmaceuticals and their five metabolites. The minimum quantifiable level of target compounds was 0.62 to 11ng·L-1. The developed analytical method was successfully applied to actual environmental water samples taken at a sewage treatment plant and a water purification plant located in the Tokyo metropolitan area. Seven out of eight target compounds were detected in the range of 50ng·L-1 to 16μg·L-1 after processing in primary sedimentation tanks in the sewage treatment plant. Six compounds were also detected in the range of 13 to 38ng·L-1 in downstream river water. Both carbamazepine and its metabolite were persistent in groundwater and even in finished water in the water purification plant.