Simultaneous analysis of 10 trihalomethanes at nanogram per liter levels in water using solid-phase microextraction and gas chromatography mass-spectrometry

Trihalomethanes are predominantly formed during disinfection of water via reactions of the oxidant with natural organic matter. Even though chlorinated and brominated trihalomethanes are the most widespread organic contaminants in drinking water, when iodide is present in raw water iodinated trihalomethanes can also be formed. The formation of iodinated trihalomethanes can lead to taste and odor problems and is a potential health concern since they have been reported to be more toxic than their brominated or chlorinated analogs. Currently, there is no published standard analytical method for I-THMs in water. The analysis of 10 trihalomethanes in water samples in a single run is challenging because the iodinated trihalomethanes are found at very low concentrations (ng/L range), while the regulated chlorinated and brominated trihalomethanes are present at much higher concentrations (above μg/L). An automated headspace solid-phase microextraction technique, with a programmed temperature vaporizer inlet coupled with gas chromatography-mass spectrometry, was developed for routine analysis of 10 trihalomethanes i.e. bromo-, chloro- and iodo-trihalomethanes in water samples. The carboxen/polydimethylsiloxane/divinylbenzene fiber was found to be the most suitable. The optimization, linearity range, accuracy and precision of the method are discussed. The limits of detection range from 1 ng/L to 20 ng/L for iodoform and chloroform, respectively. Matrix effects in treated groundwater, surfacewater, seawater, and secondary wastewater were investigated and it was shown that the method is suitable for the analysis of trace levels of iodinated trihalomethanes in a wide range of waters.The method developed in the present study has the advantage of being rapid, simple and sensitive. A survey conducted throughout various process stages in an advanced water recycling plant showed the presence of iodinated trihalomethanes at ng/L levels

Analysis of free amino acids in natural waters by liquid chromatography-tandem mass spectrometry

This paper reports a new analytical method for the analysis of 18 amino acids in natural waters using solid-phase extraction (SPE) followed by liquid chromatography-electrospray tandem mass spectrometry (LC–MS/MS) operated in multiple reaction monitoring mode. Two different preconcentration methods, solid-phase extraction and concentration under reduced pressure, were tested in development of this method. Although concentration under reduced pressure provided better recoveries and method limits of detection for amino acids in ultrapure water, SPE was a more suitable extraction method for real samples due to the lower matrix effects for this method. Even though the strong cation exchange resin used in SPE method introduced exogenous matrix interferences into the sample extracts (inorganic salt originating from the acid–base reaction during the elution step), the SPE method still incorporates a broad sample clean-up and minimised endogenous matrix effects by reducing interferences originating from real water samples. The method limits of quantification (MLQ) for the SPE LC–MS/MS method in ultrapure water ranged from 0.1 to 100 μg L−1 as N for the different amino acids. The MLQs of the early eluting amino acids were limited by the presence of matrix interfering species, such as inorganic salts in natural water samples. The SPE LC–MS/MS method was successfully applied to the analysis of amino acids in 3 different drinking water source waters: the average total free amino acid content in these waters was found to be 19 μg L−1 as N, while among the 18 amino acids analysed, the most abundant amino acids were found to be tyrosine, leucine and isoleucine

Odour reduction strategies for biosolids produced from a Western Australian wastewater treatment plant: Results from Phase I laboratory trials

This study investigated sources of odours from biosolids produced from a Western Australian wastewater treatment plant and examined possible strategies for odour reduction, specifically chemical additions and reduction of centrifuge speed on a laboratory scale. To identify the odorous compounds and assess the effectiveness of the odour reduction measures trialled in this study, headspace solid-phase microextraction gas chromatography-mass spectrometry (HS SPME-GC-MS) methods were developed. The target odour compounds included volatile sulphur compounds (e.g. dimethyl sulphide, dimethyl disulphide and dimethyl trisulphide) and other volatile organic compounds (e.g. toluene, ethylbenzene, styrene, p-cresol, indole and skatole). In our laboratory trials, aluminium sulphate added to anaerobically digested sludge prior to dewatering offered the best odour reduction strategy amongst the options that were investigated, resulting in approximately 40% reduction in the maximum concentration of the total volatile organic sulphur compounds, relative to control

Laboratory Scale Investigations of Potential Odour Reduction Strategies in Biosolids

This study investigated sources of odours from biosolids produced from a Western Australian wastewater treatment plant and examined potential odour reduction strategies on a laboratory scale. Odour reduction methods that were trialled included chemical additions and reduction of centrifuge speed. Chemical addition trials were conducted by adding alum, polyaluminium chloride or ferric chloride to digested sludge that had been sampled prior to the dewatering stage. Trials of chemical addition (alum) to plant dewatered cake were also undertaken. The impact of reducing centrifuge speed on biosolids odour was also investigated using a laboratory scale centrifuge calibrated to operate such that the shear forces on the sample would, as closely as possible, represent those on the plant. To identify the odorous compounds present in biosolids and to assess the effectiveness of the odour reduction measures, headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS SPME-GC-MS) methods were developed. Target odour compounds included volatile sulphur compounds (e.g. DMS, DMDS, DMTS) and other volatile organic compounds (toluene, thylbenzene, styrene, p-cresol, indole, skatole and geosmin). In our laboratory trials, aluminium sulphate added to digested sludge prior to dewatering offered the best odour reduction strategy among the options that were investigated, resulting in approximately 40% reduction in peak concentration of the total volatile organic sulphur compounds (TVOSC), relative to a control sample

Analysis of emerging disinfection by-products in drinking water

Disinfection by-products (DBPs) were detected in drinking water over 35 years ago. Since then identification of DBP species has closely paralleled advances in analytical chemistry. Today over 600 individual DBP species, representing several chemical classes, have been identified in drinking water. Potential DBP health concerns reported by some toxicology and epidemiology studies include elevated risks of developing certain cancers or adverse reproductive outcomes. New drinking water regulations must be evidence-based, requiring next-generation DBP studies that better link advances in analytical methods with a focus on DBPs that have the biological plausibility to cause the adverse outcomes we seek to avoid. The strategic development of the nationwide DBP occurrence study in the United States has helped to refocus today's global DBP research agenda toward a new generation of emerging DBPs of health significance. Notable DBP classes now being studied include: halonitromethanes, haloamides, halogenated furanones, haloaldehydes, haloquinones, as well as N-nitrosamines and iodo-DBPs. Improvements in extraction, separation, and detection technologies have improved our ability to identify DBP species that were once difficult, if not impossible, to detect by gas chromatography methods. Liquid chromatography/mass spectrometry applications are providing new insights into the monitoring of nonvolatile, high-molecular-weight, highly polar, hydrophilic, and thermally labile target compounds in drinking water. On-line monitoring and expanded studies evaluating swimming pool exposures are the latest innovations in the ongoing interdisciplinary research related to the analysis of emerging DBPs

Breakpoint chlorination and free-chlorine contact time: Implications for drinking water N-nitrosodimethylamine concentrations

North American drinking water utilities are increasingly incorporating alternative disinfectants, such as chloramines, in order to comply with disinfection by-product (DBP) regulations. N-Nitrosodimethylamine (NDMA) is a non-halogenated DBP, associated with chloramination, having a drinking water unit risk two to three orders of magnitude greater than currently regulated halogenated DBPs. We quantified NDMA from two full-scale chloraminating water treatment plants in Alberta between 2003 and 2005 as well as conducted bench-scale chloramination/breakpoint experiments to assess NDMA formation. Distribution system NDMA concentrations varied and tended to increase with increasing distribution residence time. Bench-scale disinfection experiments resulted in peak NDMA production near the theoretical monochloramine maximum in the subbreakpoint region of the disinfection curve. Breakpoints for the raw and partially treated waters tested ranged from 1.9:1 to 2.4:1 (Cl2:total NH3-N, M:M). Bench-scale experiments with free-chlorine contact (2 h) before chloramination resulted in significant reductions in NDMA formation (up to 93%) compared to no free-chlorine contact time. Risk-tradeoff issues involving alternative disinfection methods and unregulated DBPs, such as NDMA, are emerging as a major water quality and public health information gap