RESUMO
RESUMO O estudo teve como objetivo o desenvolvimento e a validação de um método analítico para detecção e quantificação de ácidos haloacéticos por meio da extração líquido-líquido e da análise por cromatografia gasosa acoplada à espectrometria de massas. Para a validação, consideraram-se parâmetros como linearidade, precisão, limites de detecção e quantificação e seletividade. Adicionalmente, aplicou-se o método para avaliar a formação de ácidos haloacéticos em ensaios de cloração de células de Cylindrospermopsis raciborskii com o oxidante hipoclorito de cálcio, simulando situações em estações de tratamento de água. O método apresentou baixo tempo de análise, excelente seletividade, precisão, repetitividade e sensibilidade, com possibilidade de aplicação para análises de rotina em substituição à cromatografia a gás por captura de elétrons. Observou-se a formação de ácidos haloacéticos durante os ensaios com doses de 2,5 e 5,0 mg.L-1 do oxidante, com destaque para os ácidos dicloroacético e tricloroacético.
ABSTRACT The objective of the study was to develop and validate an analytical method for the detection and quantification of haloacetic acids through liquid-liquid extraction and gas chromatography-mass spectrometry analysis. For validation, parameters such as linearity, precision, detection and quantification limits, and selectivity were considered. Additionally, the method was applied to evaluate the formation of haloacetic acids in in Cylindrospermopsis raciborskii cell chlorination assays with the calcium hypochlorite oxidant, simulating full scale situations in water treatment plants. The method presented low analysis time, excellent selectivity, precision, repeatability, and sensitivity, with possibility of application for routine analysis in substitution gas chromatography by electron capture. The formation of haloacetic acids was observed during the tests with 2.5 and 5.0 mg.L-1 doses of the oxidant, with emphasis on dichloroacetic and trichloroacetic acids.
RESUMO
Haloacetic acids are the main disinfection by-products in chlorinated drinking water,which are known or suspected to carcinogenic. Many countries have promulgated haloacetic acids as the routine monitoring item for drinking water safety. In order to better control the formation of haloacetic acids in chlorinated drinking water,many techniques and analysis methods were exploited. This review summarized the development of techniques and analysis methods and the comparative analysis was conducted in technique cost,method detection limit,sensitivity,resistance to disturb and sample pretreatment. The electrospray mass spectrometry is the best choice,but the instrument and operation cost is much higher,so the standard method based on the gas chromatography will still be the popular method for drinking water quality analysis.
RESUMO
Objective Characteristics of removing disinfection by-product precursors by conventional processes were studied in a certain city that lives on surface water. Methods Gas chromatography was employed to determine trihalomethane and haloacetic acids in water. Sampling time was from January to April in 2003 and there were 5 sampling sites each time. Results Trihalomethane formation potential(THMFP) in the source water was 15.00-39.83 ?g/L and in the supply drinking water it was 13.42-13.85 ?g/L. It showed that the conventional water treatment processes played a positive role in controlling THMFP. Haloacetic acids formation potential(HAAFP) in source water changed from 61.79 ?g/L to 78.72 ?g/L and the average removing rate of HAAFP by conventional processes was 44.13%. Conclusion Further studies are needed about organic matters in different kinds of source water in different areas and reactivity of DBP precursors with chlorine and DBPs generating ability. All these studies will contribute to control DBPs in drinking water.