Determination of pharmaceuticals and antiseptics in water by solid-phase extraction and gas chromatography/mass spectrometry: analysis via pentafluorobenzylation and stable isotope dilution.
ABSTRACT A sensitive yet robust analytical method is presented for the simultaneous determination of 12 human pharmaceuticals (valproic acid, phenytoin, ibuprofen, gabapentin, acetaminophen, gemfibrozil, naproxen, ketoprofen, secobarbital, phenobarbital, 5-fluorouracil, and diclofenac) and 6 antiseptics (biosol, biphenylol, p-chloro-m-cresol, p-chloro-m-xylenol, chlorophene, and triclosan). The method employs solid-phase extraction (SPE) followed by a novel pentafluorobenzylation using a mixture of acetontrile/water (1/1, v/v). The method is simple to perform (derivatization can be completed in a single test tube) and eliminates the need for any solvent/SPE cartridge drying or blow-down. It affords excellent resolution, high sensitivity and reproducibility, and freedom from interference even for matrices as complex as untreated sewage. The method was applied to the analysis of sewage samples using 15 isotopically labeled surrogates, which resulted in the detection of 10 of the 12 pharmaceuticals and all of the antiseptics sought. Ten of 15 surrogates were synthesized from pure analytes by a simple H-D exchange reaction employing D(2)O and D(2)SO(4). Measured recoveries were sensitive to matrix effects and varied substantially among analytes, indicative of the limitations associated with using a single surrogate standard.
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ABSTRACT: In this report, we refer to pharmaceuticals that are widespread in the urban aquatic environment and that mainly originate from wastewater treatment plants or non-point source sewage as "wastewater-marking pharmaceuticals" (WWMPs). To some extent, they reflect the condition or trend of water contamination and also contribute to aquatic environmental risk assessment. The method reported here for screening typical WWMPs was proposed based on academic concerns about them and their concentrations present in the urban aquatic environment, as well as their properties of accumulation, persistence, eco-toxicity and related environmental risks caused by them. The screening system consisted of an initial screening system and a further screening system. In the former, pharmaceuticals were categorised into different evaluation levels, and in the latter, each pharmaceutical was given a normalised final evaluation score, which was the sum of every score for its properties of accumulation, persistence, eco-toxicity and environmental risk in the aquatic environment. The system was applied to 126 pharmaceuticals frequently detected in the aquatic environment. In the initial screening procedure, five pharmaceuticals were classified into the "high" category, 16 pharmaceuticals into the "medium" category, 15 pharmaceuticals into the "low" category and 90 pharmaceuticals into the "very low" category. Subsequently, further screening were conducted on 36 pharmaceuticals considered as being of "high", "medium" and "low" categories in the former system. We identified 7 pharmaceuticals with final evaluation scores of 1-10, 10 pharmaceuticals with scores of 11-15, 15 pharmaceuticals with scores from 16 to 20 and 4 pharmaceuticals with scores above 21. The results showed that this screening system could contribute to the effective selection of target WWMPs, which would be important for spatial-temporal dynamics, transference and pollution control of pharmaceuticals in the urban aquatic environment. However, there remains a number of pharmaceutical parameters with measured data gaps, such as organic carbon adsorption coefficients and bioconcentration factors, which, if filled, would improve the accuracy of the screening system.Environmental Science and Pollution Research 02/2014; 21(11). · 2.76 Impact Factor
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ABSTRACT: A simple and sensitive gas chromatography–electron ionization–mass spectrometry (GC-EI-MS) method using dried plasma spot testing cards was developed for determination of valproic acid and gabapentin concentrations in human plasma from patients receiving in-home medical care. We have proposed that a simple, easy and dry sampling method is suitable for in-home medical patients for therapeutic drug monitoring. Therefore, in the present study, we used recently developed commercially available easy handling cards: Whatman FTA DMPK-A and Bond Elut DMS. In-home medical care patients can collect plasma using these simple kits. The spots of plasma on the cards were extracted into methanol and then evaporated to dryness. The residues were trimethylsilylated using N-methyl-N-trimethylsilyltrifluoroacetamide. For GC-EI-MS analysis, the calibration curves on both cards were linear from 10 to 200 µg/mL for valproic acid, and from 0.5 to 10 µg/mL for gabapentin. Intra- and interday precisions in plasma were both ≤13.0% (coefficient of variation), and the accuracy was between 87.9 and 112% for both cards within the calibration curves. The limits of quantification were 10 µg/mL for valproic acid and 0.5 µg/mL for gabapentin on both cards. We believe that the present method will be useful for in-home medical care. Copyright © 2014 John Wiley & Sons, Ltd.Biomedical Chromatography 05/2014; · 1.95 Impact Factor
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ABSTRACT: A sample preparation procedure that combines a liquid-liquid extraction (LLE) with a dispersive solid-phase extraction (DSPE) has been devised to determine residues of four phenoxyacid herbicides, two aminopolycarboxylic acids and five acidic anti-inflammatory drugs in small volumes of river water samples. Two aliquots of acetone (3 and 0.5mL) were used to extract the analytes from a 10mL water sample at pH 2 containing 5mg of octadecylsilane (ODS) sorbent and NaCl at a 5.5M concentration. Acetone was isolated by the salting-out effect, collected, evaporated and the extract was treated with BF3/methanol to obtain the methyl esters of the analytes and determine them by GC with mass spectrometric detection. Recoveries were comprised between 82% and 114% with relative standard deviations about 5-15% (n=5) within a concentration range about 0.03-44µgL(-1). The amount of ODS added to sample resulted to be a significant factor in the recovery for most of the analytes as deduced from an experimental design; the sample pH was not a so critical factor. A robustness study of the proposed sample preparation was carried out as defined by Youden and Steiner and an estimation of the uncertainties of the measured concentrations was made following the EURACHEM/CITAC guidelines, too.Talanta 11/2013; 116:678-87. · 3.50 Impact Factor