Determination of Trihalomethanes in drinking water from three different water sources in Florianopolis-Brazil using purge and trap and gas chromatography

The water source to feed the public water system in Florianopolis, Santa Catarina State-Brazil is very diversified and it was used to investigate the formation of trihalomethanes (THM). A strong relationship between the presence of THM and the kind of water source was found. Water sources in contact with vegetation contained higher concentration of total trihalomethanes (TTHM). Water samples from the Cubatao-Piloes system had a mean TTHM value of 59.9 Pa L-1 while in Peri Lake, the mean TTHM was 152.3 mu g L-1. Samples from the North Shore system, based on wellsprings, had a mean TYHM of 19.4 mu g L-1. In the case of natural waters (spring water and wellsprings) THM was not observed. A system that combines purge-and-trap and gas chromatography with an electron capture detector was used in this study. After careful choice of the experimental conditions, the performance of the system was evaluated. Relative standard deviation, limit of detection and limit of quantification are 8-17 %, 0.01-0.03 mu g L-1 and 0.03-0.08 mu g L-1 respectively. Linear range falls within the range 0.1 to 8.0 mu g L-1 for all compounds. Precision ranged between 91.3 and 126.0%.