Contrary to the current expectations, the standard addition method was found to be strongly influenced by matrix effects. The proposed system for sulphite analyses, constituted by a gas diffusion unit in line with a wall-jet amperometric FIA detector modified with a supramolecular porphyrin film, was shown to be an attractive alternative to the time-consuming Monier-Williams method, allowing IOX1 chemical structure fast, reproducible and accurate analyses of free sulphite species in fruit juices.

In fact, a linear response between 0.64 and 6.4 ppm of sodium sulphite, LOD = 0.043 ppm, relative standard deviation of ±1.5% and analytical frequency of 85 analyses/h (or even more) can be obtained using the optimised conditions. In addition, the new FIA system uses small amounts of sample, consumes minute amounts of reagents, has low cost, and is suitable for online production control and monitoring. The applications will be limited in the case of too viscous samples or samples containing solid particles that may obstruct the channels and will cause fluctuations of the laminar flow of the donor and acceptor solutions. The authors gratefully acknowledge the financial support from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Instituto

do Milênio de Materiais Complexos (IM2C). “
“Chlorine is applied to drinking water in order to deactivate microorganisms and/or to ensure the residual concentrations in drinking water distribution systems, thus protecting water from microorganism regrowth. A multiplicity Lumacaftor ic50 of viral, bacterial, protozoan, and parasitic diseases can be transmitted via contaminated drinking Parvulin water. Infections can range from asymptomatic to mild discomfort, debilitation and even death (Rodriguez & Serodes, 2001). In the chlorination process, chlorine can react with natural organic matter including humic and fulvic substances. The trihalomethanes (THMs) are formed in this process, and the formation of halogenated compounds depends on the type and concentration

of natural organic matter, bromide ion concentration, chlorine form and dose, pH, temperature and organic nitrogen concentration (Aboul and Wells, 2006 and Rodriguez et al., 2004). The THMs formed are chloroform (CHCl3), dichlorobromomethane (CHCl2Br), chlorodi-bromomethane (CHClBr2) and bromoform (CHBr3) (Uyak, Ozdemir, & Toroz, 2007). In 1974, for the first time studies in the United States showed a positive correlation between water supply and cancer. There was a study conducted by EPA in 113 water treatment plants. THMs were found in all the stations that used chlorine as a disinfection process (Melnick, 1989). EPA and the European Union (EU) have set the maximum contaminant level (MCL) for THMs in drinking water at 80 and 100 μg L−1, respectively (The council of the European Union, 1998 and United States Environmental Protection Agency, 2001).