Dissolved total saccharides (DTS) and dissolved free monosaccharides (DFMS) in streamwater were determined by high‐performance liquid chromatography with pulsed amperometric detection (HPLC‐PAD). HPLC identification was verified with gas chromatography/mass spectrometry measurements. The method for DTS was improved by using a column with an anion exchange capacity of 4,500 µeq and a mobile phase of 350 mM NaOH. The detection limits for individual monosaccharides ranged from 2 to 14 nM. The average recovery for monosaccharide standards was 82% after hydrolysis, and 75% of the monosaccharides in streamwater hydrolysates were recovered following a desalting procedure. Hydrolysis of model substances showed recoveries of monosaccharides between 78 and 98%. The C.V. for a hydrolyzed stream sample was 15% for the DTS. Stream samples stored at room temperature after filtration and acidification to pH 1.1 were stable for at least 23 d. Concentrations of DTS in White Clay Creek, including sugar alcohols and amino sugars, ranged from 0.64 to 12.70 µM and accounted for 2.9–12.1% of the dissolved organic carbon pool. Neutral sugars dominated the DTS pool, and glucose and galactose were the most abundant molecules. Concentrations of DFMS ranged from 0.05 to 0.38 µM and accounted for 0.06–0.33% of the dissolved organic carbon pool.
An extraction technique using MTBE (methyl tert. butyl ether) and reagent water in combination with ion chromatography and conductivity determination was developed to quantify dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) concentrations in raw water after chlorination. The detection limit of the method was 0.45 and 1.50 microg/L for DCAA and TCAA, respectively. Mean values of recovery ranged from 90 to 96% for DCAA and 95 to 108% for TCAA. The evaluation of recovery and precision of the method indicates that the performance characteristics are comparable with gas chromatographic (GC) methods reported in literature. In addition, the procedure is simple, fast, and does not need any derivatization step. Application of the analytical method to the determination of DCAA and TCAA in real samples is shown.
In the present study an analytical method was optimized for the determination of alpha-endosulfan, beta-endosulfan, endosulfan sulfate, endosulfan ether and endosulfan lactone in small volumes of environmental aqueous samples using solid-phase microextraction (SPME) and gas chromatography-electron capture detection (GC-ECD). A 100 micro m polydimethylsiloxane (PDMS) phase was used for the extraction. The limit of detection (LOD) for the analytes varied between 0.01 and 0.03 micro g L(-1) with a relative standard deviation of 3 to 11%. The influence of the ionic strength on the extraction efficiency was investigated for the individual compounds. alpha-Endosulfan, beta-endosulfan, endosulfan sulfate and endosulfan ether were extracted successfully without salt addition. The extraction efficiency of endosulfan lactone was improved with 30% NaCl content. A general decrease in extraction efficiency for alpha-endosulfan, beta-endosulfan, endosulfan sulfate and endosulfan ether with high NaCl content (20-30%) in the solution was observed due to glass surface adsorption. No effect of dissolved organic material (DOM) on the extraction efficiency was observed. The extraction coefficients changed between Log K=2.17 and 3.33. A sample from the Antarctic region was analyzed using the optimized GC-ECD/SPME method. To confirm the results obtained for the real sample a GC with a mass spectrometer (MS) was used. Endosulfan sulfate, the most toxic metabolite of endosulfan, was found in the sample at a concentration of 0.3 micro g L(-1).
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