Occurrence and fate of the human pharmaceutical metabolite ritalinic acid in the aquatic system

To investigate the occurrence and fate of ritalinic acid – the main human metabolite of the psychostimulant drug methylphenidate – in the aquatic environment, a HPLC–electrospray–MS/MS method for the quantification of ritalinic acid in wastewater, surface water and bank filtrate was developed. Carbamazepine known as very stable in the aquatic environment was analyzed as anthropogenic marker in parallel. Furthermore, the removal of ritalinic acid was studied in a sewage treatment plant using an activated sludge system during a field study and in lab-scale plants. In good agreement between lab-scale and field studies a low removal rate of 13% and 23%, respectively, was determined. As a consequence, the concentration of ritalinic acid in the wastewater effluents were in the range of