Comparison of two validated gas-chromatographic methods for the determination of trihalomethanes in drinking water

Abstract

In this paper the results obtained using two validated gaschromatographic procedures on drinking water for the determination of trihalomethanes are compared. The volatile compounds, chloroform (CF), bromodichloromethane (BDCM), dibromochloromethane (DBCM) and bromoform (BF) were detected by purge and trap capillary column gas-chromatography with electrolytic conductivity detector (ELCD) and the simple and rapid gas-chromatographic method by electron capture detector (ECD) after liquid-liquid extraction with n-pentane. For purge and trap ELCD method the response for the volatile compounds was linear for the concentrations of 0.5 to 40 µg/L. For liquid-liquid extraction ECD method the response was linear for the concentrations of 0.5 to 100 µg/L. The comparison of both methods was achieved by analyzing samples of drinking water collected in the city of São. Paulo, Brazil. The ratios of concentrations obtained by the two methods (ECD/ELCD) were as follows: l.l3 ± 0.9 for chloroform; 0.93 ± 0.15 for BDCM and 0.92 ± 0.17 for DBCM. Bromoform was not detected in the drinking water samples. The ratio of 1.08 ± 0.047 for total triahalomethane-THMt (the sum of the three compounds) shows the equivalence of the compared methods.

Evaluating gas chromatography with a halogen-specific detector for the determination of disinfection by-products in drinking water

“…The volatile DBPs, e.g., THMs, HANs, and HKs, have been quantified using GC-MS (Richardson 2010 ) or GC with electron capture detection (ECD) (Chinn et al 2007 ; Hodgeson et al 1990 ; Tominaga and Mídio 2003 ). For the determination of more polar DBPs with ionizable functional groups (e.g., HAAs), derivatization is necessary prior to separation with GC.…”

Detecting Trihalomethanes Using Nanoporous-Carbon Coated Surface-Acoustic-Wave Sensors

“…8 Used in combination with purge and trap, GC-ECD can also achieve LODs <1 ppb for individual THM detection; however, all of these methods require some form of sample preparation. [9][10][11][12][13][14] Other detectors with GC have also been demonstrated, including microwave plasma emission, 15 thermal conductivity detection, 16 and atomic emission detection. 17 Arrays of surface acoustic wave (SAW) device sensors were successfully demonstrated to detect a large number of VOCs, including both chloroform and bromoform at 10 ppb concentrations in water, in combination with purge and trap methods, to develop a cost-effective alternative for on-site measurement of VOCs.…”