Concentrations of ketamine (KET) and its metabolite, norketamine (NK) in sewage water and surface water in Beijing were examined by HPLC-MS/MS. Samples were collected from all the thirteen sewage treatment plants in the urban area and four rivers flowing through the city. Average influent concentrations of KET and NK in 2013 summer ranged from <MQL to (19.5±5.1) ng·L-1 and <MQL to (6.2±2.1) ng·L-1, respectively. The calculated loads of KET and NK ranged from (0.1±0.0) to (8.6±2.4) mg·(1000 inh·d)-1 and (0.3±0.1) to (3.2±1.1) mg·(1000 inh·d)-1, respectively. The removal rate during treatment was low and even negative at some plants for KET and NK. KET was widely detected in surface waters (<MQL to 17.8 ng·L-1), whereas NK was below MQL in all surface water samples. Concentration of KET in Tonghui River was higher than those in most of the STPs, indicating direct disposal of KET and/or direct discharge of sewage into the river.
Keywords: Beijing; ketamine; norketamine; sewage; surface water.