ABSTRACT
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.
ABSTRACT
There exists a high demand for fast, simple, and reliable methodologies for determining the presence of organochlorine pesticides (OCPs) on environmental samples. Moreover, the toxicity and accumulation of potential OCPs in several environments have led to the development of technologies that achieve their removal from contaminated waters. In this study, a novel method combining a dispersive liquid-liquid microextraction procedure based on the solidification of floating organic drop is developed and validated for the extraction, preconcentration, and determination of 10 OCPs: α-BHC, p,p'-DDE, δ-BHC, dieldrin, p,p'-DDT, endosulfan I, endosulfan sulfate, heptachlor, heptachlor epoxide (isomer B), and methoxychlor in water samples. The results show that the calibration curves were linear for all the studied compounds, and the coefficients of correlation higher than 0.99. The variation coefficient for precision and accuracy was lower than 10%, and the accuracy ranged from 93 to 105%. Low limit of detection and limit of quantification values ranging from 0.06-3.00 ng mL-1 and 0.20-10 ng mL-1 were obtained, respectively. The capability of the proposed method was confirmed using an analysis of the water samples before and after the degradation process; this was achieved by employing nanomaterials, while performing an analysis of 160 real samples that were sourced from a Brazilian river. A cobalt-doped magnetite was applied for the environmental remediation of the studied compounds, and it was verified that the novel material has the potential to be used in environmental remediation with a degradation efficiency exceeding 80% for the majority of the studied compounds.
Subject(s)
Hydrocarbons, Chlorinated , Magnetite Nanoparticles , Pesticides , Water Pollutants, Chemical , Brazil , Gas Chromatography-Mass Spectrometry , Hydrocarbons, Chlorinated/analysis , Pesticides/analysis , Water , Water Pollutants, Chemical/analysisABSTRACT
RESUMO Estudos demonstram que a utilização do cloro em estações de tratamento de água (ETA) pode contribuir para a formação de subprodutos orgânicos halogenados indesejados, tais como os trialometanos (TAM), quando há presença de matéria orgânica algogênica, composta de algas e cianobactérias. A Microcystis aeruginosa é uma espécie de cianobactéria com frequentes registros em eventos de florações no país e é relacionada com a formação de TAM durante a cloração da água. Desse modo, este estudo teve como objetivo o desenvolvimento e a validação do método analítico por extração líquido-líquido para detecção e quantificação de TAM por cromatografia gasosa acoplada à espectrometria de massas (ELL-CG-EM), bem como a aplicação deste para avaliar a formação de TAM em ensaios de cloração de células de Microcystis aeruginosa, simulando situações em ETA. O método obteve baixo tempo de análise (< 12 minutos), excelente seletividade, precisão, repetitividade e sensibilidade, com possibilidade de aplicação para análises de rotina em detrimento de outras técnicas consideradas mais automatizadas. Foram observadas alta demanda de cloro durante os ensaios e elevada concentração dos subprodutos quando submetida à dose de cloro gasoso (Cl2) de 2,5 e 5 mg.L-1, com destaque para o triclorometano, sendo outras espécies de monitoramento obrigatório não detectadas ou não formadas, o que pode ser justificado pela ausência de bromo.
ABSTRACT Studies have shown that the use of chlorine in water treatment plants (WTPs) can contribute to formation of undesirable halogenated organic by-products, such as trihalomethanes (THMs), when algae and cyanobacteria are present. Microcystis aeruginosa is a cyanobacteria specie with frequent recordings of flowering events in the country and is related to the formation of THMs during water chlorination. Thus, the objective of this study was to develop and validate Liquid-Liquid Extraction the analytical method for detection and quantification of THMs by gas chromatography coupled to mass spectrometry (LLE-GC-MS), as well as the application of the method to evaluate the formation of TAMs from Microcystis aeruginosa cells chlorination tests, simulating situations in WTPs. The method obtained low time of analysis (< 12 minutes), excellent selectivity, precision, repeatability and sensitivity, with possibility of application for routine analysis to the detriment of other techniques considered more automated. High chlorine demand was observed during the tests and high concentration of by-products when submitted to the chlorine gas (Cl2) dose of 2.5 and 5 mg.L-1, with emphasis on trichloromethane. Other species of mandatory monitoring were not detected or not formed, justified by the absence of bromine.
ABSTRACT
In this study, a method was developed to evaluate the degradation of haloacetic acids (HAAs) in water by a heterogenous Fenton-like process catalyzed by cobalt-doped magnetite nanoparticles (Fe3 - xCoxO4), extraction of the contaminants by liquid-liquid extraction (LLE), and analysis by gas chromatography-mass spectrometry (GC-MS). The developed method was efficient in the degradation of HAAs, with the following degradation values: 63%, 62%, 30%, 39%, 37%, 50%, 84%, 41%, and 79% for monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, trichloroacetic acid, bromochloroacetic acid, dibromoacetic acid, bromodichloroacetic acid, dibromochloroacetic acid, and tribromoacetic acid compounds, respectively. Through the application of the Allium cepa test, the cytotoxicity, genotoxicity, and mutagenicity of HAAs were evaluated. The results confirm its genotoxic and mutagenic effects on Allium cepa meristematic cells. Through this study, it was possible to verify the effectiveness of the developed method and its potential as a proposal for environmental remediation.
Subject(s)
Biological Assay , Chloroacetates/toxicity , Mutagens/toxicity , Toxicity Tests , Acetates/toxicity , Acetic Acid , DNA Damage , Dichloroacetic Acid/toxicity , Environmental Monitoring , Gas Chromatography-Mass Spectrometry , Hydrocarbons, Brominated/toxicity , Trichloroacetic Acid/toxicity , Water/analysis , Water SupplyABSTRACT
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.