Extraction of mono- and dicarboxylic acids from a curative water (original) (raw)
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Fresenius' journal of analytical chemistry, 2000
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.
Comparison of isolation methods of urinary organic acids by high-performance liquid chromatography
Journal of chromatography, 1982
Four methods for extracting organic acids from human urine prior to analysis by high-performance liquid chromatography (HPLC) were compared. The methods were manual solvent extraction with ethyl acetate and diethyl ether, continuous solvent extraction, anion exchange with pyridinium acetate as the eluting solvent and anion exchange with hydrochloric acid as the eluting solvent. All four methods produced samples that could be analyzed by reversed-phase HPLC, but the continuous solvent extraction and anion exchange with pyridinium acetate methods gave the best reproducibilities (approximately 6% relative standard deviations). Pretreatment of the urine with barium hydroxide and hydroxylamine hydrochloride prior to anion exchange did not markedly alter the HPLC profiles.
Indian Journal of Clinical Biochemistry, 2016
Pre analytical process of extraction for accurate detection of organic acids is a crucial step in diagnosis of organic acidemias by GCMS analysis. This process is accomplished either by solid phase extraction (SPE) or by liquid-liquid extraction (LLE). Both extraction procedures are used in different metabolic laboratories all over the world. In this study we compared these two extraction procedures in respect of precision, accuracy, percent recovery of metabolites, number of metabolites isolated, time and cost in a resource constraint setup. We observed that the mean recovery from SPE was 84.1 % and by LLE it was 77.4 % (p value \0.05). Moreover, the average number of metabolites isolated by SPE and LLE was 161.8 ± 18.6 and 140.1 ± 20.4 respectively. The processing cost of LLE was economical. In a cost constraint setting using LLE may be the practical option if used for organic acid analysis.
Journal of chromatography. A, 2018
The paper presents a new procedure for the determination of organic acids in a complex aqueous matrix using ultrasound-assisted dispersive liquid-liquid microextraction followed by injection port derivatization and GC-MS analysis. A deep eutectic solvent (choline chloride: 4-methylphenol in a 1:2 mol ratio) was used both as an extracting solvent and as a derivatizing agent to yield ion pairs which were next converted to methyl esters of organic acids in a hot GC injection port. The procedure was optimized in terms of selection of a deep eutectic solvent, disperser solvent, and the ratio of their volumes, pH, salting out effect, extraction time, injection port temperature and time of opening the split valve. The developed procedure is characterized by low LOD (1.7-8.3 μg/L) and LOQ (5.1-25 μg/L) values, good repeatability (RSD ranging from 4.0 to 6.7%), good recoveries for most of the studied analyte (81,5-106%) and a wide linear range. The procedure was used for the determination of...
Analysis of haloacetic acids in water by a novel technique: simultaneous extraction– derivatization
Water Research, 1998
ÐA simple and novel method has been developed for the analysis of haloacetic acids (HAAs), disinfection by-products (DBPs) formed during water chlorination. This method can be used to determine six of these acids, including chloro, bromo and chloro/bromo acids. The validity and reliability of the method were tested over 6 months on twenty French water samples. 50 ml of water are percolated over an ion-exchange resin, the strong acids are trapped and then eluted and simultaneously esteri®ed to give their methyl derivatives by a methyl alcohol solution acidi®ed with sulfuric acid. The esters are extracted by cyclohexane and analyzed by gas chromatography with electron-capture detection (GC/ ECD). Dalapon is used as a tracer in order to monitor the extraction process and trichloropropane as the internal standard. The detection limits for the HAAs analyzed are between 0.1 mg/l and 0.2 mg/l. The analysis of dierent water samples showed that all the haloacetic acids, except monobromoacetic acid, were present. The total HAAs in water originating from surface waters was less than 50 mg/l, but could exceed 100 mg/l for water originating from reservoir waters. In underground waters, the concentration of HAAs was negligible.
Journal of Chromatography A, 2004
Seven polymeric solid-phase extraction (SPE) sorbents were evaluated with regard to their ability to extract acidic, neutral and basic pharmaceuticals and estrogens simultaneously from water at neutral pH. Highest recoveries (70-100%) for the majority of the analytes were obtained with styrene-methacrylate and styrene-N-vinylpyrrolidone co-polymers. The latter one (Oasis HLB) was chosen for further refinement of an extraction method for the quantitative determination of acidic and neutral drugs in surface water samples at detection limits below 1 ng/l. A sequential elution protocol was applied for clean-up and separation of the extracted analytes into fractions suitable for further compound specific processing. The neutral analytes as well as the acidic compounds after derivatisation were quantified by GC-MS. Caffeine, ibuprofen, its metabolites and diclofenac were detected in river water samples in the 1-100 ng/l range.
European Journal of Mass Spectrometry
A method for the analysis of 11 haloacetic acids in water samples has been developed. It involves enrichment of the target analytes from water samples by solid-phase extraction, derivatization to methyl esters, and gas chromatography coupled with tandem mass spectrometry determination. Gas chromatography conditions were optimized for a good separation of all haloacetic acids in a short runtime. Data were acquired in the multiple reaction monitoring mode. Six solid-phase extraction sorbents among the most widely used in environmental analysis were tested. Bakerbond SDB was retained because it has been shown to provide the best results for a large class of targeted haloacetic acids. The performances of the developed method have been assessed according to the French Standard NF T 90-210. The calibration curves for all the studied haloacetic acids had consistent slopes with r2 values > 0.99. Quantification limits between 0.01 and 0.50 µg l−1 were achieved. Satisfactory repeatability ...
Chromatographia, 2013
An ion exclusion chromatography (IELC) comparison between a conventional ion exchange column and an ultra-high performance liquid chromatography (UHPLC) dynamically surfactant modified C18 column for the separation of an aliphatic carboxylic acid and two aromatic carboxylic acids is presented. Professional software is used to optimize the conventional IELC separation conditions for acetylsalicylic acid and the hydrolysis products: salicylic acid and acetic acid. Four different variables are simultaneously optimized including H 2 SO 4 concentration, pH, flow rate, and sample injection volume. Thirty different runs are suggested by the software. The resolutions and the time of each run are calculated and feed back to the software to predict the optimum conditions. Derringer's desirability functions are used to evaluate the test conditions and those with the highest desirability value are utilized to separate acetylsalicylic acid, salicylic acid, and acetic acid. These conditions include using a 0.35 mM H 2 SO 4 (pH 3.93) eluent at a flow rate of 1 mL min-1 and an injection volume of 72 L. To decrease the run time and improve the performance, a UHPLC C18 column is used after dynamic modification with sodium dodecyl sulfate. Using pure water as a mobile phase, a shorter analysis time and better resolution are achieved. In addition, the elution order is different from the IELC method which indicates the contribution of the reversed-phase mode to the separation mechanism.