Validation of a robust LLE-GC-MS method for determination of trihalomethanes in environmental samples.

An analytical liquid-liquid extraction-gas chromatography-mass spectrometry (LLE-GC-MS) method was developed and validated for the determination of trihalomethanes (THMs) in environmental samples. The compounds studied were trichloromethane (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and tribromomethane (TBM). The calibration curves for the THMs showed high linearity in the range of 1-1000 µg L-1. Studies of intra-day and inter-day precision, limit of detection (LOD), limit of quantification (LOQ), accuracy, and recovery were performed with low (10 µg L-1), medium (40 µg L-1), and high (200 µg L-1) concentrations of THMs. The intra-day and inter-day precision RSD varied in the ranges of 0.17-6.95% and 0.26-15.70%, respectively. No statistical differences were observed between the analysis of the concentration of certified reference materials (CRM 4M8140-U) and the values reported by CRM, indicating the good accuracy of the proposed method. The recovery was 88.75-119.21%. The LOD and LOQ were smaller than 0.13 and 0.40 µg L-1. Compared with reported LLE-GC-MS methods, the validated method had similar LOD and enhanced LOQ, precision, accuracy, and recovery. Also, the method is robust, selective to THMs, and the total time for the extraction and GC separation of THMs is about 18 min. The method was useful for detecting and quantifying low concentrations of TCM (40-80 µg L-1) formed by water chlorination in the presence of Microcystis aeruginosa cyanobacteria, thus demonstrating its applicability for monitoring THMs in real samples.

Occurrence of endocrine disrupting compounds in water sources of Belo Horizonte Metropolitan Area, Brazil.

Endocrine disrupting compounds (EDCs) have attracted the attention of the scientific community because of the effects of EDCs on aquatic fauna and the potential threat they pose to human health. There are a handful of papers on the monitoring of EDCs in Brazilian surface waters, hence this research was aimed at assessing, by using liquid chromatography coupled to mass spectrometry (LC-MS), the presence of 17 beta-estradiol, 17 alpha-ethynylestradiol and 4-nonylphenol in surface waters used for supplying the Belo Horizonte Metropolitan Area, Minas Gerais state, Brazil. The one-year monitoring period of three water sources showed that 4-nonylphenol was detected in all samples in a concentration range of 44 to 1918 ng L(-1), whilst the natural and synthetic estradiols were hardly detected (only in approximately 15% of samples) and always in low concentrations (2 to 54 ng L(-1)). Samples of partially treated water, collected in three water treatment plants before the chlorination step, showed that the steps of prechlorination, flocculation-sedimentation and sand filtration did not efficiently remove the EDCs studied.