This paper illustrates the challenge faced by analytical chemists when trying to measure selected compounds representative of various classes of prescription and hospital drugs. Because hundreds of drugs belonging to a wide variety of chemical groups are allowed for use, an array of analytical methods has to be implemented. As an example, as part of the European Poseidon Project, five different methods were required to measure eight drugs and personal care products. These methods are discussed in detail. Examples of application to surface and ground waters from the Paris area are also reported. The antibiotics roxithromycin and sulfamethoxazole were detected for the first time in the Seine River downstream of Paris. The behaviour of the eight target compounds during aquifer recharge and drinking water treatment is described. An incident involving the detection of micrograms per litre levels of the personal care product Galaxolide in a drinking water distribution system is reported. The value of the pharmaceuticals and personal care products selected as potential indicators is also discussed.
