Determination of human and veterinary antibiotics in indirect potable reuse systems

This paper reports the optimization and validation of an analytical method for the determination of the residual concentration of the prescription antibiotics metronidazole, trimethoprim, sulfamethoxazole, azithromycin, clindamicyn, clarithromycin, erythromycin-H2O, roxithromycin and tylosin in wastewater and advanced treated wastewater. The method applied was used in a study of removal efficiency of these compounds at a full scale operational water reclamation plant using microfiltration-reverse osmosis (MF-RO) (Kwinana, Western Australia). The analytical procedure involves off-line solid-phase extraction (SPE) followed by liquid chromatography - tandem mass spectrometry (LC-MS/MS) operated in multiple reaction monitoring mode. Method validation included determination of linearity, accuracy, precision, method limits of quantitation (MLQs), reproducibility and matrix effect. SPE recoveries were generally higher than 89% for both pre- and post- RO water, except for erythromycin which yielded approximately 50% recovery. The overall precision of the method was better than 16% RSD (relative standard deviation), for all compounds and matrices. MLQ ranged between 23-53 ng/L and 2.5-31 ng/L for pre- and post- RO water, respectively. In-house reproducibility expressed as RSD was generally better than 10%. Inter-laboratory tests revealed a generally good agreement between concentrations of antibiotics reported by all participants. Results demonstrate that MF/RO treatment is capable of removing antibiotics present at relevant environmental concentration in secondary effluent (from the low to-mid ng/L range) to below MLQs (2.5-31 ng/L), and more importantly, three to six orders of magnitude below the health guideline values developed for this project. Estimated RO rejections ranged between > 91 and 99%

Rapid analysis of iodinated X-ray contrast media in secondary and tertiary treated wastewater by direct injection liquid chromatography-tandem mass spectrometry

The iodinated x-ray contrast media (ICM) are the most widely administered intravascular pharmaceuticals and are known to persist in the aquatic environment. A rapid method using direct injection liquid chromatography-tandem mass spectrometry (DI-LC-MS/MS) has been developed to measure eight ICM. These include iopamidol, iothalamic acid, diatrizoic acid, iohexol, iomeprol, iopromide, plus both ioxaglic acid and iodipamide, which have not previously reported in the literature. The LC-MS/MS fragmentation patterns obtained for each of the compounds are discussed and the fragments lost for each transition are identified. Matrix effects in post-RO water, MQ water, tap water and secondary effluent have also been investigated. The DI-LC-MS/MS method was validated on both secondary and tertiary treated wastewater, and applied to samples from an advanced activated sludge wastewater treatment plant (WWTP) and a water recycling facility using microfiltration (MF) and reverse osmosis (RO) in Perth, Western Australia. As well as providing information of the efficacy for RO to remove specific ICM, these results also represent the first values of ICM published in the literature for Australia

Chlorination of Amino Acids: Reaction Pathways and Reaction Rates

Chlorination of amino acids can result in the formation of organic monochloramines or organic dichloramines, depending on the chlorine to amino acid ratio (Cl:AA). After formation, organic chloramines degrade into aldehydes, nitriles and N-chloraldimines. In this paper, the formation of organic chloramines from chlorination of lysine, tyrosine and valine were investigated. Chlorination of tyrosine and lysine demonstrated that the presence of a reactive secondary group can increase the Cl:AA ratio required for the formation of N,N-dichloramines, and potentially alter the reaction pathways between chlorine and amino acids, resulting in the formation of unexpected by-products. In a detailed investigation, we report rate constants for all reactions in the chlorination of valine, for the first time, using experimental results and modelling. At Cl:AA = 2.8, the chlorine was found to first react quickly with valine (5.4x104 M-1 s-1) to form N-monochlorovaline, with a slower subsequent reaction with N-monochlorovaline to form N,N-dichlorovaline (4.9x102 M-1 s-1), although some N-monochlorovaline degraded into isobutyraldehyde (1.0x10-4 s-1). The N,N-dichlorovaline then competitively degraded into isobutyronitrile (1.3x10-4 s-1) and N-chloroisobutyraldimine (1.2x10-4 s-1). In conventional drinking water disinfection, N-chloroisobutyraldimine can potentially be formed in concentrations higher than its odour threshold concentration, resulting in aesthetic challenges and an unknown health risk

Isotope dilution liquid chromatography - tandem mass spectrometry for simultaneous identification and quantification of beta-casomorphin 5 and beta-casomorphin 7 in yoghurt

A highly selective and sensitive liquid chromatography–tandem mass spectrometry method was developed and validated for the simultaneous identification and quantification of beta-casomorphin 5 (BCM5) and beta-casomorphin 7 (BCM7) in yoghurt. The method used deuterium labelled BCM5-d10 and BCM7-d10 as surrogate standards for confident identification and accurate and quantification of these analytes in yoghurt. Linear responses for BCM5 and BCM7 (R2 = 0.9985 and 0.9986, respectively) was observed in the range 0.01–10 ng/μL. The method limits of detection (MLDs) in yoghurt extracts were found to be 0.5 and 0.25 ng/g for BCM5 and BCM7, respectively. Analyses of spiked samples were used to provide confirmation of accuracy and precision of the analytical method. Recoveries relative to the surrogate standards of these spikes were in the range of 95–106% for BCM5 and 103–109% for BCM7. Precision from analysis of spiked samples was expressed as relative standard deviation (%RSD) and values were in the range 1–16% for BCM5 and 1–6% for BCM7. Inter-day reproducibility was between 2.0–6.4% for BCM5 and between 3.2–6.1% for BCM7. The validated isotope dilution LC–MS/MS method was used to measure BCM5 and BCM7 in ten commercial and laboratory prepared samples of yoghurt and milk. Neither BCM5 nor BCM7 was detected in commercial yoghurts. However, they were observed in milk and laboratory prepared yoghurts and interestingly their levels decreased during processing. BCM5 decreased from 1.3 ng/g in milk to 1.1 ng/g in yoghurt made from that milk at 0 day storage and <MLQ at 1 and 7 days storage. BCM7 decreased from 1.9 ng/g in milk to <MLQ in yoghurts immediately after processing. These preliminary results indicate that fermentation and storage reduced BCM5 and BCM7 concentration in yoghurt

Determination of sixteen polycyclic aromatic hydrocarbons in aqueous and solid samples from an Italian wastewater treatment plant

This study addresses the issue of whether it is possible to accurately predict the removalefficiencies of metals of environmental concern (i.e., Al, Ag, As, B, Ba, Cd, Cr, Fe, Mn, Hg, Ni,Pb, Cu, V, and Zn) in a wastewater treatment plant. The plant in question (at Fusina, Venice,Italy) is fed by mixed wastes from municipal and industrial sources (300 000 equivalentinhabitants) and discharges the treated effluent into the Venice lagoon. The year-long samplingcampaign (2001-2002) yielded a substantial amount of analytical data and relatively wide rangesof concentrations of metals in the influent samples, which made it possible to study the removalefficiencies by plotting the terms (inlet concentration - outlet concentration) vs (inlet concentration)for each metal investigated. The data in the plots were fitted using the linear regressionmodel Y ) BX. The slope rates (terms B), which were estimated by the least-squares method,have been adopted as the removal efficiencies, and they can be considered as constants in theconcentration ranges recorded in this work. The relative abundance of metals in the rawwastewaters feeding Fusina WWTP followed the order Al &gt; Fe &gt; B &gt; Zn &gt; Ba &gt; Mn &gt; Cu &gt;Pb &gt; Hg ) Ni &gt; Cr ) As &gt; V &gt; Ag &gt; Cd, while in the effluent the order was Fe &gt; Al &gt; Zn &gt;Mn &gt; Ba &gt; Ni &gt; Cu &gt; Pb &gt; Cr &gt; Ag &gt; As &gt; Hg ) V &gt; Cd. The removal percentages (%) of themetals were Al ) 92 ( 1; Ag ) 94 ( 1; As ) 76 ( 3; B ) n.d.; Ba ) 85 ( 2; Cd ) 85 ( 2; Cr )87 ( 1; Fe ) 90 ( 1; Mn ) 61 ( 2; Hg ) 93 ( 1; Ni ) 50 ( 3; Pb ) 92 ( 1; Cu ) 93 ( 1; V )74 ( 2; and Zn ) 75 ( 3

A review of the determination of organic compounds in Bayer process liquors

Bayer process liquors present a difficult and complex matrix to the analytical chemist, and the history of the application of modern analytical techniques to this problem is a case study in innovation. All Bayer process liquors contain organic compounds, in amounts varying from traces to several grams per litre. The total organic carbon content of Bayer liquors may be less than 5 g/L up to as much as 40 g/L. The presence of these organic impurities is of concern to Bayer technologists because they can have significant impacts on the economics of the process and the quality of the product. This review examines the history and current state-of-the-art of the analysis of organics in Bayer process liquors, and provides guidance on the applicable techniques matched to a comprehensive list of the compounds most likely to be present

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

Validation of Dual Membrane Treatment for Indirect Potable Reuse

The Western Australia's Premier's Collaborative Research Program (PCRP) project 'Characterising Treated Wastewater for Drinking Purposes Following Reverse Osmosis Treatment' commenced in October 2005, to determine the potential risks of replenishing drinking water aquifers with MF/RO treated secondary wastewater from Perth?s wastewater treatment plants. A brief report on the project won the Michael Flynn Award for the best poster paper at Ozwater 10. The results included those published in Water, February 2010, by Rodriguez et al, entitled Efficiency of RO for removal of Chemical Contaminants. Consequently, this version has been drafted to cover the other aspects of the study, principally the identification of suitable indicators which could be used to validate treatment performance