RESUMEN
Comparison of four methods including liquid-liquid extraction (LLE), direct aqueous injection (DAI), purge and trap (PAT) and head space (HS) were carried out in this work for determination of volatile organic compounds (VOCs) including trihalomethanes (THMs) in drinking water. This comparison is made especially to show the advantages and disadvantages and specifically the different detection limits (DL) that can be obtained for a given type of analysis. LLE is applicable only for determination of the THMs concentrations, while DAI, PAT, HS methods with different DL each of them are applicable for all VOCs, with PAT to be the most sensitive. Sampling apparatus and procedure for all these methods except of PAT are very simple and easy, but possible disadvantages for LLE and DAI are the low sensitivity and especially the detection only of THMs with LLE.
Asunto(s)
Trihalometanos/análisis , Contaminantes Químicos del Agua/análisis , Abastecimiento de Agua , Técnicas de Química Analítica/métodos , Monitoreo del Ambiente/métodos , Compuestos Orgánicos/análisis , Sensibilidad y Especificidad , Manejo de Especímenes , VolatilizaciónRESUMEN
The behaviour of the haloketones (HKs) 1,1-Dichloropropanone (1,1-DCP), 1,1,1-Trichloropropanone (1,1,1-TCP) and 1,3-Dichloropropanone (1,3-DCP) in ultrapure water solutions and in fortified drinking water samples was investigated. Their concentrations were determined at regular time intervals by the use of a gas chromatography-electron capture detector (GC-ECD) method. Two different temperatures were studied. The results have shown that HKs decompose both in ultrapure water solutions and in drinking water samples. The decomposition rates are higher in the drinking water samples, especially at higher temperature. 1,1,1-TCP is the compound which decomposes fastest followed by 1,3-DCP and 1,1-DCP. Chloroform was formed both in the ultrapure water solutions and in the drinking water samples, probably due to the decomposition of 1,1,1-TCP. In the drinking water samples, formation of chloral hydrate was also observed.
Asunto(s)
Cetonas/análisis , Contaminantes Químicos del Agua/análisis , Abastecimiento de Agua , Cromatografía de Gases , Monitoreo del Ambiente/métodos , Temperatura , Purificación del AguaRESUMEN
On a monthly basis, on a one year period, disinfection by-products (DBPs) and volatile organic compounds (VOCs) were measured in raw water and in treated water of four water treatment plants (WTP) as well as from eight representative points of the distribution network of Athens. Liquid-liquid extraction (LLE) method followed by gas chromatography (GC) with electron capture detection (ECD) and mass spectrometry (MS) was used for the determination of the DBPs, while the purge-and-trap (PAT) technique followed by GC-MS was used for the determination of the VOCs. The DBPs that have been studied included trihalomethanes (THMs), haloacetonitriles (HANs), haloketones (HKs), chlorate hydrate (CH) and chloropicrin (CP), while forty-one VOCs were also studied including THMs. Chloroform (CM), dichlorobromomethane (DCBM), chlorodibromomethane (CDBM) were the major organic compounds found in all treated water samples. HANs, HKs, CH and CP were detected in treated samples but at lower concentrations.
Asunto(s)
Desinfectantes/química , Trihalometanos/análisis , Contaminantes Químicos del Agua/análisis , Abastecimiento de Agua , Monitoreo del Ambiente , Cromatografía de Gases y Espectrometría de Masas , Grecia , Compuestos Orgánicos/análisis , VolatilizaciónRESUMEN
An investigation of the decomposition of dihaloacetonitriles (DHANs) in water solutions and fortified drinking water samples was conducted. The concentrations of dichloroacetonitrile (CHCl2CN, DCAN), bromochloroacetonitrile (CHBrClCN, BCAN) and dibromoacetonitrile (CHBr2CN, DBAN) were determined by a gas chromatography mass spectrometry (GC-MS) method at regular time intervals and different temperatures. The effect of sodium thiosulfate (Na2S2O3), which is used as a preservative in water samples, was also examined. The rates of decomposition were determined for each compound. The results show that the reactions are faster in fortified drinking water samples than in ultrapure water solutions. They are also favored at higher temperature, especially when sodium thiosulfate is present. The highest decomposition rate is shown by DCAN, followed by BCAN and DBAN, while at the presence of sodium thiosulfate the decomposition of DBAN is the fastest.
Asunto(s)
Acetonitrilos/metabolismo , Abastecimiento de Agua , Cromatografía de Gases y Espectrometría de Masas , TemperaturaRESUMEN
An investigation into the occurrence of volatile organic compounds (VOCs) was conducted for a period of two years in the surface waters of Northern Greece. Samples from four rivers and five lakes were taken seasonally and analyzed for VOCs. The analysis has been performed by purge-and-trap (PAT) gas chromatographic-mass spectrometric (GC-MS) technique. The most commonly encountered VOCs in surface waters were chloroform, carbon tetrachloride, trichloroethylene, dichlorobromomethane, tetrachloroethylene, and chlorodibromomethane.