Determination of Antibiotics in Brazilian Surface Waters Using Liquid Chromatography–Electrospray Tandem Mass Spectrometry Marco Antonio F. Locatelli • Fernando F. Sodre ´ • Wilson F. Jardim Received: 26 March 2010 / Accepted: 10 May 2010 / Published online: 10 June 2010 Ó Springer Science+Business Media, LLC 2010 Abstract A liquid chromatography–electrospray tandem mass spectrometry (LC–MS/MS) method for the determi- nation of antibiotics in water was developed and applied to Brazilian surface waters. Amoxicillin, ampicillin, cefalexin (CEF), ciprofloxacin (CIP), norfloxacin (NOR), sulfa- methoxazole, tetracycline (TET), and trimethoprim were selected as target compounds due to their high consump- tion pattern in Brazil. LC and MS conditions were opti- mized to produce the maximum analytic response for each compound. Anion exchange and polymeric solid-phase extraction cartridges, in series, were employed during the extraction procedures. Recovery, linear range, limit of detection (LOD), and limit of quantification were calcu- lated. LOD varied from 0.13 ng L -1 for CIP and NOR to 0.76 ng L -1 for TET. Surface water samples from the Atibaia watershed (Sa ˜o Paulo State, Brazil) were analyzed. Results showed that seasonal and anthropogenic aspects dictated the levels of antibiotics in the samples. An overall frequency of detection of 55% was observed during the rainy period, whereas a higher percentage (88%) was noticed for samples collected during the dry season. In the Atibaia River, sample concentrations ranged from 29 ng L -1 for CEF to 0.5 ng L -1 for NOR. In a sewage-affected stream, however, concentrations up to 2422 ng L -1 CEF were found. Antibiotics represent a broad class of pharmaceuticals that are currently used worldwide in diverse applications. Data from the National Health Surveillance Agency (ANVISA) show that the annual consumption of antibiotics in Brazil exceeded 1200 tons in 2004 and 2005 (ANVISA 2006). According to this source, 28 b-lactams accounted for [ 70% of the antibiotics consumed in both years. The consumption of antibiotics during 2005 amounted to 390 tons of amoxicillin (AMX), followed by 184 tons of ampicillin (AMP), 163 tons of cefalexin (CEF), 133 tons of sulfamethoxazole (SMX), 45 tons of tetracycline (TET), 38 tons of norfloxacin (NOR), 30 tons of ciprofloxacin (CIP), and 27 tons of trimethoprim (TMP), among others. These compounds are responsible for [ 80% of all antibiotics consumed in Brazil and were selected to be investigated in this work. Despite the high total consumption, there is a lack of outpatient sales information for antibiotics in Brazil. This information is commonly used to extract the number of defined daily doses (DDDs) for a region according to the World Health Organization Collaborating Centre for Drug Statistics Methodology (WHOCC 2009). The DDD is based on the average daily dose used for the main indica- tion of a drug and is suitable for comparisons of drug use over time and in different countries. An estimate of Bra- zilian DDDs for different groups of antibiotics is presented in Fig. 1 together with values for the United States and some European countries (Goossens et al. 2007; Davey et al. 2008). The Brazilian values in Fig. 1 were computed using consumption data for 77 active substances in 2005 (ANVISA 2006) and the individual DDD for each active antibiotic (WHOCC 2009). Systemic antibiotic use in Brazil is moderate compared with other countries listed in Fig. 1. The consumption pattern is characterized by high use of M. A. F. Locatelli Á W. F. Jardim (&) Chemistry Institute, University of Campinas, POB 6154, Campinas, SP 13083-970, Brazil e-mail: wfjardim@iqm.unicamp.br F. F. Sodre ´ Chemistry Institute, University of Brası ´lia, POB 4478, Brası ´lia, DF 72919-910, Brazil 123 Arch Environ Contam Toxicol (2011) 60:385–393 DOI 10.1007/s00244-010-9550-1