Caffeine as a chemical tracer for contamination of urban rivers

ABSTRACT The growing urbanization in urban centers have continuously contributed to the deterioration of water quality in rivers. The use of caffeine as a chemical tracer for anthropic activities is an approach to the environmental monitoring of urban waterbodies, as its use is limited to humans and less susceptible to sampling error comparing to other traditional parameters for anthropic pollution. To analyze the possibility of using caffeine as a water quality parameter, the anthropic influence over three watersheds (Atuba, Belem and Palmital) from the Greater Curitiba was observed over five sampling campaigns. The caffeine was analyzed by liquid chromatography tandem diode array detection, after the solid phase extraction. Traditional parameters of water quality monitoring, such as ammoniacal nitrogen, thermotolerant coliforms, biochemical oxygen demand and orthophosphate, were measured for comparison. The results indicate anthropic influence over the basins, probably due to the lack of infrastructure, thus leading to the assumption of untreated domestic wastewater being discharged. The most degraded river was the Belem river (caffeine concentration of 23.08 µg.L-1). Caffeine presented itself as an appropriate approach for environmental monitoring, presenting a good correlation with the traditional parameters, such as for thermotolerant coliforms (R = 0.7375).