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PubMed2005

Solid state partitioning of trace metals in suspended particulate matter from a river system affected by smelting-waste drainage.

The partitioning of particulate trace metals was investigated during one year of monthly sampling of suspended particulate matter (SPM) at eight sites along the Lot-Garonne fluvial system, known for its polymetallic pollution. The chemical partitioning in five operationally defined fractions (exchangeable/carbonate, Fe/Mn oxides, organic matter/sulfides, acid soluble, residual) was determined using a multiple single extraction approach. This approach showed that Cd, Zn, Pb and Cu were mainly associated with acid soluble phases (84-95%, 65-88%, 61-82% and 55-80% of the respective total metal content), and therefore showed a high mean potential of mobilization and bioavailability. In the Riou-Mort River, draining the smelting-wastes, Zn, Cd and Mn showed high mobility as they were little associated with the residual fraction (1-2%) and mainly bound to the 'exchangeable' fraction of SPM (60-80%), probably weakly adsorbed on amorphous freshly-precipitated sulfide and/or oxide phases. Upstream and downstream of the anthropogenic source of metallic pollution, Mn and Cd, and Zn to a lesser extent, remained highly reactive. The other trace metals were mainly associated with the residual fraction and thus less mobile. However, the multiple single extraction scheme revealed that the most reactive transport phases were non-selectively extracted by the conventional extractants used here. These selectivity problems could not have been observed if sequential extraction was used.

Journal Article↗
PubMed2003

Preferential extraction of hydrocarbons from fire debris samples by solid phase microextraction.

Headspace analysis by extraction/GC-MS is a common method of detecting volatile hydrocarbon accelerants in fire debris samples. Solid-phase microextraction was tested to determine if there is selective extraction of chemically distinct compounds. It was found that both the polydimethylsiloxane (PDMS) and Carboxen/PDMS solid phase microextraction fibers show preferential extraction of aliphatic or aromatic compounds from the headspace depending on fiber type and temperature. The Carboxen/PDMS fiber type showed particular (although not exclusive) selectivity for extraction of aromatic hydrocarbons. Other experimental considerations of SPME are noted.

Journal Article↗
PubMed2006

Injection port derivatization following ion-pair hollow fiber-protected liquid-phase microextraction for determining acidic herbicides by gas chromatography/mass spectrometry.

Injection port derivatization following ion-pair hollow fiber-protected liquid-phase microextraction (LPME) for the trace determination of acidic herbicides (2,4-dichlorobenzoic acid, 2,4-dichlorophenoxyacetic acid, 2-(2,4-dichlorophenoxy)propionic acid, 3,5-dichlorobenzoic acid, 2-(2,4,5-trichlorophenoxy)propionic acid) in aqueous samples by gas chromatography/mass spectrometry (GC/MS) was developed. Prior to GC injection port derivatization, acidic herbicides were converted into their ion-pair complexes with tetrabutylammonium chloride in aqueous samples and then extracted by 1-octanol impregnated in the hollow fiber. Upon injection, ion pairs of acidic herbicides were quantitatively derivatized to their butyl esters in the GC injection port. Thus, several parameters related to the derivatization process (i.e., injection temperature, purge-off time) were evaluated, and main parameters affecting the hollow fiber-protected LPME procedure such as extraction organic solvent, ion-pair reagent type, pH of aqueous medium, concentration of ion-pair reagent, sodium chloride concentration added to the aqueous medium, stirring speed, and extraction time profile, optimized. At the selected extraction and derivatization conditions, no matrix effects were observed. This method proved good repeatability (RSDs <12.3%, n = 6) and good linearity (r2 > or = 0.9939) for spiked deionized water samples for five analytes. The limits of detection were in the range of 0.51-13.7 ng x L(-1) (S/N =3) under GC/MS selected ion monitoring mode. The results demonstrated that injection port derivatization following ion-pair hollow fiber-protected LPME was a simple, rapid, and accurate method for the determination of trace acidic herbicides from aqueous samples. In addition, this method proved to be environmentally friendly since it completely avoided open derivatization with potentially hazardous reagents.

Acids↗
PubMed1998

Determination of polychlorinated biphenyls in soybean infant formulas by gas chromatography.

A method previously developed for the analysis of organohalogenated compounds in dairy products is now validated for polychlorinated biphenyls (PCBs) determination in soybean infant formulas. The results of this study are consistent with those found for PCBs in powdered full-fat milk. The methodology is based on a solid-liquid extraction step enabling a semi-selective extraction of the apolar lipids of the matrix without affecting the efficiency for the recovery of PCBs. Mean recoveries for the spiked coplanar congeners studied were in the 88-114% range, with relative standard deviations (R.S.D.s) lower than 9.8%. The R.S.D.s related to the determination of endogenous PCBs were in the 1.5-10.0% range. The validated methodology was applied to the PCB analysis in different trademarks of soybean infant formulas commercialised in Spain. Toxic tetraequivalents of tetrachlorodibenzo-p-dioxin and daily intake corresponding to each one were calculated and compared with values previously published and with those found in literature for human breast milk in different countries.

Chromatography, Gas↗
PubMed2000

Liquid chromatographic-mass spectrometric analysis of supercritical-fluid extracts of rosemary plants.

A two-step supercritical fluid extraction process of rosemary leaves, on a pilot plant scale, is proposed to divide the oleoresin into two fractions with different antioxidant activities and essential oil composition. Rosemary leaves were extracted by using different conditions of pressure and temperature as well as different conditions for fractionation of the extracts. Conditions can be tuned to selectively extract one antioxidant fraction with almost no residual aroma. In the present investigation, the antioxidant fraction was exhaustively studied in terms of antioxidant activity measurements as well as of chemical composition. An LC-MS method was adapted to perform the analysis and identification of the compounds responsible for the antioxidant activity of the extracts. Different extraction and fractionation conditions were studied in order to correlate the process conditions with the antioxidant activities obtained.

Antioxidants↗
PubMed2001

High-performance liquid chromatographic assay for the determination of 2'-deoxy-3'-thiacytidine (lamivudine) in human plasma.

A method for the quantification of 2'-deoxy-3'-thiacytidine (lamivudine, 3-TC), which incorporated the use of 3-isobutyl-methylxanthine as internal standard (I.S.) was developed and validated in human plasma, using HPLC with UV absorbance detection. Using solid-phase extraction, 3-TC and I.S. were selectively extracted from human plasma. Subsequently, chromatographic separation was performed using a YMC phenyl column with ion-pair chromatography and detection at 270 nm. The method was validated over a concentration range of 10 to 5,000 ng/ml using 0.5 ml of human plasma. The extraction recovery for both 3-TC and I.S. was greater than 95%. The determination of inter- and intra-day precision (RSD) was less than 10% at all concentration levels, while the inter- and intra-day accuracy (% difference) was less than 6%.

Chromatography, High Pressure Liquid↗
PubMed1998

Supercritical fluid extraction of pesticides from meat: a systematic approach for optimisation.

A method for quantification of pesticide residues in meat and fatty matrices was developed using supercritical fluid extraction (SFE). The SFE method allows selective extraction of residues and subsequent gas chromatography analysis without further clean-up. Quantification was done by GC using nitrogen-phosphorus detection and electron capture detection. Initial method development was made using organophosphorus pesticides (OPPs). The dependence of fat and OPP residue recovery on supercritical fluid density, temperature, flow rate and extraction time was investigated through a reduced factorial design. Since temperature and density were found to have pronounced effect on the recovery of OPPs these extraction parameters were studied using a new arbitrary measure for co-extractivity. An optimisation score was established as relative pesticide recovery subtracted by relative fat recovery. Using this algorithm a response plane was modelled varying the primary factors temperature and density. The applicability of this approach and the algorithm was verified. The polarity range covered by the SFE method was demonstrated using OPPs: chlorpyrifos, chlorpyrifos-methyl, malathion, pirimifos-methyl and prothiofos. Additionally the final method was evaluated using four pesticides that are not OPPs: carbofuran, phorate, procymidone and vinclozolin. All pesticides showed good recovery (78-95%), and limits of detection (0.01-0.03 mg kg-1) and limits of determination (0.01-0.05 mg kg-1) meet the requirements set by the European Council (Directive 96/33/EEC). Compared to traditional methods based on organic solvent extraction, the SFE method is fast, less labour intensive, uses smaller amounts of potentially harmful solvents and has the potential to be fully automated.

Animals↗
PubMed1985

A fixation procedure suitable for autoradiography of endogenous long-chain acyl carnitine.

A tissue processing procedure was evaluated for fixation of endogenous long-chain acyl carnitine (LCA) to facilitate autoradiographic subcellular localization of this amphiphile. Suspensions of neonatal rat myocytes labeled with exogenous 14C-palmitoyl carnitine retained 85.2% of the radiolabel after tissue processing. Autoradiography demonstrated no significant translocation of radiolabeled LCA from myocytes to unlabeled sheep erythrocytes mixed in equal proportions and processed together. To evaluate endogenous LCA fixation, cultured myocytes were incubated for 3 days with 3H-carnitine. Radioactivity was distributed in LCA, short-chain acyl carnitine, and free carnitine pools in proportion to the physiological concentrations of the metabolites traced. Before tissue processing, LCA contained 4.5% of total radioactivity. After tissue processing, labeled water-soluble components were lost and 88% of the retained radioactivity was in the LCA pool. The enrichment of endogenous LCA radioactivity was attributable to the selective extraction of endogenous short-chain and free carnitine. Nearly 75% of endogenous LCA was preserved. In contrast, 99.5% of both endogenous short-chain and free carnitine were extracted. Thus, endogenous LCA can be selectively preserved, permitting quantitative subcellular localization of this amphiphile with ultrastructural autoradiography.

Animals↗
PubMed1982

Biosynthesis of hyaluronic acid in cultures of chondrocytes from the Swarm rat chondrosarcoma.

The synthesis of hyaluronic acid by cultured chondrocytes from the Swarm rat chondrosarcoma was examined using [3H]glucosamine as a precursor. [3H]Hyaluronate in samples was estimated as the specific unsaturated disaccharide released by incubation with chondroitinase ABC under conditions where all [3H]hyaluronate was converted to disaccharide even in the presence of excess chondroitin sulfate. The products of digestion of chondroitin sulfate and hyaluronate were well separated by cellulose thin layer chromatography. A second method involving quantitation of the 3H-oligosaccharides released by digestion with Streptomyces hyaluronidase gave nearly identical results. [3H]Hyaluronate formed about 12% of the [3H]glycosaminoglycans synthesized by the chondrocytes, although levels as high as 20% were found in one set of cultures. The incorporation of [3H]glucosamine into chondroitin sulfate and hyaluronate was linear and at a constant ratio over a 24-h period. The distributions of [35S]proteoglycans, [3H]chondroitin sulfate, and [3H]hyaluronate between the medium, a 4.0 M guanidine HCl extract of the cell layer, and the cell residue, were investigated over 24 h. Both hyaluronate and proteoglycan accumulated in the medium with little retention in the cell layer. Pulse-chase experiments indicated that a greater proportion of the [3H]hyaluronate than the [3H]chondroitin sulfate was initially retained in the cells, but that subsequently [3H]hyaluronate accumulated more rapidly in the medium, suggesting differences in the transit time through the extracellular matrix for the two molecules once secreted from the cell. In cultures labeled for 6 h, 4.0 M guanidine HCl extracted 66% of the hyaluronate and 58% of the chondroitin sulfate associated with the cell layer, while 1% Zwittergent, a zwitterionic detergent, extracted 59% and 29%, respectively. The selective extraction with detergent suggests that there is a pool of hyaluronate in the cell layer which is not associated with proteoglycan aggregates. Equilibrium density gradient centrifugation of cell layer extracts and culture media, under dissociative conditions, showed that 89% of the [3H]hyaluronate banded at densities between 1.43-1.55 g/ml with a peak at 1.47 g/ml. Disaccharide analyses of the gradient fractions showed that the main proteoglycan component contained primarily chondroitin 4-sulfate but also revealed a minor proteoglycan at lower densities which was considerably enriched in chondroitin 6-sulfate.

Animals↗
PubMed2004

Selective digestion and novel cleanup techniques for detection of benzo[a]pyrene diol epoxide-DNA adducts by capillary electrophoresis/mass spectrometry.

Benzo[a]pyrene (BP) is a ubiquitous environmental polycyclic aromatic hydrocarbon (PAH) which, upon metabolic conversion to reactive benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), has been found to attach covalently to DNA. Given the low level of DNA adducts typically present in vivo or in vitro, an essential first step prior to capillary electrophoresis/mass spectrometry (CE/MS) (or liquid chromatography/mass spectrometry (LC/MS)) analysis of the DNA digests is the removal of the bulk non-adducted nucleotides, enzymes or salts, and isolation of enriched adducts. This report focuses on the development of novel sample handling methods aimed at facilitating the analysis of BPDE-DNA adducts by CE/MS. This approach involves a simple variation on the digestion procedure, in combination with the use of metal affinity ZipTips for the more efficient cleanup of BPDE-DNA adducts formed in vitro for subsequent CE/MS analysis. The previously described digestion procedure, consisting of micrococcal nuclease, spleen phosphodiesterase and nuclease P1, allows for selective dephosphorylation of normal nucleotides, while leaving adducted nucleotides intact. Metal affinity ZipTips, typically used for selective extraction of phosphopeptides, were used here for extraction of adducted nucleotides. The utility of metal affinity SPE was tested on mixtures of dG and dGp, wherein nucleotide extracts contained no detectable nucleosides by CE/UV analysis. An in vitro BPDE-DNA incubation was then digested using the above procedure. Metal affinity solid-phase extraction (SPE) was subsequently used for the selective isolation of phosphorylated components, i.e., adducted nucleotides, from the mixture of enzymes and non-adducted nucleosides. SPE extracts were enriched in nucleotide adducts and analyzed using sample stacking and CE/MS. This method has several advantages over previously described cleanup procedures for dGp-BPDE adducts: fast, simple, uses commercially available materials, no need for excessive dilution (small scale), the suitability for use with automation, and possible applicability to other bulky hydrophobic adducts.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed2001

Towards an understanding of solvent extraction--electroanalytical characterization of chloride-leaching solutions.

Solvent extraction has been employed to purify media simulating chloride-leaching solutions resulting from complex sulfide concentrate processing, and cyclic voltammetry (CV) has been chosen to characterize those hydrometallurgical aqueous phases. The possibilities of the CV technique were investigated by the evaluation of the adequacy of a specific organic extractant, triisobutylphosphine sulfide, aimed to efficiently and selectively extract silver from a complex chloride medium, additionally containing tenfold to 40-fold molar concentrations of iron, copper and lead. The influence of the oxidation state of the metallic ions present in the feed solution, namely Cu(II) and Cu(I), is considered. The possibilities of CV analysis for the characterization of stripping solutions are also illustrated.

Journal Article↗
PubMed2004

Efficient isolation of polyaromatic fraction from aliphatic compounds in complex extracts using dimethylformamide-pentane partitionings.

A liquid-liquid partitioning method was optimized for the rapid and quantitative separation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) from aliphatic hydrocarbons in complex primary extracts. This technique was based on the selective extraction of PAHs and PCBs from an aliphatic solvent into dimethylformamide (DMF). Partition experiments demonstrated that the optimal performance was achieved with a DMF (5% H2O)-n-pentane binary system. The optimized application of two consecutive DMF (5% H2O)-n-pentane treatments to extracts from two different polluted sediments facilitated the elimination of alkanes and unresolved complex mixture by more than 94% while the average recoveries of spiked deuterated-PAHs and 13C labeled PCBs ranged from 84 to 94 and 75 to 96%, respectively.

Dimethylformamide↗
PubMed2002

Supercritical fluid extraction for the detection of 2-dodecylcyclobutanone in low dose irradiated plant foods.

Supercritical carbon dioxide extraction [152 bar (15,200 kPa), 80 degrees C, 4 ml min(-1), 60 min], performed on lipids (2 g) previously extracted from irradiated plant foods, allowed a selective extraction of 2-dodecylcyclobutanone and its further detection by gas chromatography-mass spectrometry in 50 Gy irradiated cowpeas and 100 Gy irradiated rice. However, because of the higher quantities of lipid impurities in these test samples compared to those present in meat samples, a longer and slightly more polar capillary column than the one proposed in the official standard EN 1785 method should be used to obtain a satisfactory resolution.

Chromatography, Gas↗
PubMed2002

Supercritical fluid extraction and high-performance liquid chromatographic determination of phloroglucinols in St. John's Wort (Hypericum perforatum L.).

A small-scale supercritical fluid extraction (SFE) method was developed for the selective extraction of phloroglucinols from St. John's wort (SJW) leaf/flower mixtures using supercritical carbon dioxide (CO(2)). The extraction efficiency was investigated as influenced by pressure, temperature, time, and modifier. The optimized condition of SFE was carried out at 3.80 x 10(4) kpa (5500 psi) and 50 degrees C. Samples were held in static extraction for 10 min, followed by a dynamic extraction for 90 min at the flow rate of 1 mL/min. A simple and sensitive HPLC method was developed for the analysis of hyperforin and adhyperforin, the major phloroglucinols, in the SFE extract of SJW.

Chromatography, High Pressure Liquid↗
PubMed1998

Selective detergent-extraction from mixed detergent/lipid/protein micelles, using cyclodextrin inclusion compounds: a novel generic approach for the preparation of proteoliposomes.

A novel generic approach is described for the selective extraction of detergents from mixed detergent/lipid/protein micelles for the preparation of proteoliposomes of defined lipid-protein ratio. The approach is based on the much higher affinity of inclusion compounds of the cyclodextrin type for detergents in comparison with bilayer-forming lipids. This approach has distinct advantages over other procedures currently in use. It produces good results with all detergents tested, independent of type and critical micelle concentration, and appears to be generally applicable. It yields nearly quantitative recovery of membrane protein in the proteoliposome fraction. Finally, no large excess of lipid is required; a molar ratio of lipid to protein of 100 to 1 already produces proteoliposomes with functional membrane protein, but higher ratios are well tolerated. The size of the vesicles thus obtained depends on the detergent used. Separation of the resulting proteoliposomes from the detergent-cyclodextrin complexes was most easily achieved by centrifugation through a discontinuous sucrose gradient. A variety of detergents was tested in this procedure on the bovine rod visual pigment rhodopsin in combination with retina lipids. In all cases good yields of proteoliposomes were obtained, which contained fully functional rhodopsin.

Animals↗
PubMed2003

Comparison of the mutagenic activity of XAD4 and blue rayon extracts of surface water and related drinking water samples.

The combination of mutagenicity tests and selective extraction methodologies can be useful to indicate the possible classes of genotoxic organic contaminants in water samples. Treated and source water samples from two sites were analyzed: a river under the influence of an azo dye-processing plant discharge and a reservoir not directly impacted with industrial discharges, but contaminated with untreated domestic sewage. Organic extraction was performed in columns packed with XAD4 resin, that adsorbs a broad class of mutagenic compounds like polycyclic aromatic hydrocarbons (PAHs), arylamines, nitrocompounds, quinolines, antraquinones, etc., including the halogenated disinfection by-products; and with blue rayon that selectively adsorbs polycyclic planar structures. The organic extracts were tested for mutagenicity with the Salmonella assay using TA98 and TA100 strains and the potencies were compared. A protocol for cleaning the blue rayon fibers was developed and the efficiency of the reused fibers was analyzed with spiked samples. For the river water samples under the influence of the azo-type dye-processing plant, the mutagenicity was much higher for both blue rayon and XAD4 extracts when compared to the water from the reservoir not directly impacted with industrial discharges. For the drinking water samples, although both sites showed mutagenic responses with XAD4, only samples from the site under the influence of the industrial discharge showed mutagenic activity with the blue rayon extraction, suggesting the presence of polycyclic compounds in those samples. As expected, negative results were found with the blue rayon extracts of the drinking water collected from the reservoir not contaminated with industrial discharges. In this case, it appears that using the blue rayon to extract drinking water samples and comparing the results with the XAD resin extracts we were able to distinguish the mutagenicity caused by industrial contaminants from the halogenated disinfection by-products generated during water treatment.

Cellulose↗
PubMed1985

An improved technique for extracting catecholamines from body fluids.

This paper describes a technique for selectively extracting catecholamines from body fluids prior to quantification by high-performance liquid chromatography with electrochemical detection. The technique is a two-stage process, the first stage involves the extraction of cations from the sample whilst the second stage is a liquid-liquid extraction involving the complexation of the cationic catecholamines with diphenylborate. This technique provides a very specific extraction procedure which results in chromatograms with no interfering compounds, and gives absolute recoveries of 70-80% for noradrenaline (NA), adrenaline (A) and dihydroxybenzylamine (internal standard), with similar relative recoveries of the 3 compounds. The intra-assay coefficients of variation for the measurement of catecholamines in venous plasma taken from resting subjects, are 8-9% for both NA and A, whilst the inter-assay values are 8% for NA and 20% for A.

Aluminum Oxide↗
PubMed2004

Tocopherol measurement in edible products of vegetable origin.

Since natural antioxidants present increasing interest for food industry due to their beneficial effect on health, new potential sources have been screened among edible aromatic plants and a microalgae, Spirulina platensis. The determination was performed after optimising a previously validated method, because important differences have been found among values described in literature for tocopherol content in products of vegetable origin. Values obtained ranged from 3.42 mg alpha-tocopherol/100 g of dill to 132.2 mg/100 g of fresh bay and from 0.14 mg gamma-tocopherol/100 g of spearmint to 3.45 mg/100 g of parsley. In all cases results were calculated from fresh leaves. Preliminary experiments were developed with bay (Laurus nobilis) plant to devise the supercritical fluid extraction of tocopherols, generating environmentally friendly processes to selectively extract fractions enriched with antioxidant compounds while removing fractions corresponding to essential oils, that is, those that correspond to the characteristic aroma of the plants. Another striking result has been the tocopherol content in the microalgae, 1.3 mg alpha-tocopherol/100 g of dried commercial spirulina, which do not justify the supposed source of antioxidant vitamins. Results suggest the need of more reliable determinations of tocopherols in vegetable sources to be included in databases.

Chromatography, Supercritical Fluid↗