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Solid-phase Extraction (solid-phase + extraction)
Kinds of Solid-phase Extraction Terms modified by Solid-phase Extraction Selected AbstractsDetermination of Diclofenac in Urine Samples by Molecularly-Imprinted Solid-Phase Extraction and Adsorptive Differential Pulse VoltammetryELECTROANALYSIS, Issue 15 2007Laura Fernández-Llano Abstract A molecularly imprinted polymer for diclofenac (DCF) was prepared by thermal polymerization over silica beads using 2-(dimethylamino)ethyl-methacrylate as functional monomer. After silica elimination by HF treatment, the polymer was applied to the selective solid-phase extraction of the drug from urine followed by its quantification by adsorptive differential pulse voltammetry. Results indicate that the drug could be selectively extracted from the sample and quantified at clinically relevant concentrations (,g/mL). [source] Development of a Solid-Phase Extraction,Enzyme-Linked Immunosorbent Assay for the Determination of 17,-19-Nortestosterone Levels in Antifatigue Functional FoodsJOURNAL OF FOOD SCIENCE, Issue 8 2009Yan Zhang ABSTRACT:, 17,-19-nortestosterone (17,-NT) has been illegally used in antifatigue functional foods to promote muscle growth and improve endurance. A rapid and sensitive solid-phase extraction,enzyme-linked immunosorbent assay (SPE-ELISA) method was developed and successfully applied to analyze the levels of 17,-NT in antifatigue functional foods. A polyclonal antibody against 17,-NT was produced from rabbits immunized with the 17,-NT-BSA conjugate, and a competitive direct enzyme-linked immunosorbent assay was developed for the rapid detection of 17,-NT. The concentration causing 50% inhibition (IC50) and the limit of detection (LOD) were found to be 0.08 and 0.0055 ng/mL, respectively; this was better than methods previously reported that had a LOD of 2.4 ng/mL. C18 cartridges were investigated for use in removing the effects of matrix in foods, and the sample purification protocol was optimized. Using the developed SPE-ELISA method, recoveries of functional food samples were obtained in the range of 71% to 91.5%. Moreover, 2 kinds of antifatigue functional foods were analyzed using the established ELISA and HPLC methods. The correlation coefficient of the results obtained using the 2 methods was greater than 0.98. Thus, the preliminary evaluation of the SPE-ELISA method proved that it is a specific, sensitive, and precise tool that can be used for the practical detection of 17,-NT in various antifatigue functional food samples. [source] ChemInform Abstract: Amide Bond Formation with a New Fluorous Carbodiimide: Separation by Reverse Fluorous Solid-Phase Extraction.CHEMINFORM, Issue 12 2008Carlos del Pozo Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Solid-Phase Extraction of Metoprolol onto (Methacrylic acid- ethylene glycol dimethacrylate)-based Molecularly Imprinted Polymer and Its Spectrophotometric DeterminationCHINESE JOURNAL OF CHEMISTRY, Issue 4 2010Mohammad Saber Tehrani Abstract A new adsorbent for molecularly imprinted solid phase extraction (MISPE) of metoprolol was synthesized using methacrylic acid (MAA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linking agent causing a non-covalent, bulk, thermal radical-polymerization. Control polymer (non-imprinted polymer) was prepared under well defined conditions without the use of metoprolol. The synthesized polymers were characterized by IR spectroscopy, X-ray diffraction and thermal analysis techniques. This polymer was used for the rapid extraction and preconcentration of metoprolol from real samples prior to spectrophotometric determination. Extraction efficiency and the influence of flow rates of sample and stripping solutions, pH, type of eluent for elution of metoprolol from polymer, break through volume and limit of detection were studied. The detection limit of the proposed method is 0.4 ng·mL,1. The method was applied successfully to the recovery and determination of metoprolol in tablets, human urine and plasma samples. [source] Determination of flurbiprofen enantiomers in plasma using a single-isomer amino cyclodextrin derivative in nonaqueous capillary electrophoresis,ELECTROPHORESIS, Issue 17 2008Anne Rousseau Abstract A nonaqueous capillary electrophoresis (NACE) assay was developed for the separation and determination of flurbiprofen enantiomers in plasma samples using 6-monodeoxy-6-mono(3-hydroxy)propylamino-,-cyclodextrin as chiral selector. The nonaqueous background electrolyte was made up of 40,mM ammonium acetate in methanol (MeOH), and flufenamic acid was employed as internal standard. Solid-phase extraction was used for sample cleanup prior to the NACE separation. The NACE method reproducibility was optimized by evaluating different capillary washing sequences between runs. After having tested various conditions, trifluoroacetic acid (1,M) in MeOH was finally selected. Concerning the solid-phase extraction procedure, good and reproducible analyte recoveries were obtained using MeOH for protein denaturation and a polymeric phase combining hydrophobic interactions with anion exchange properties (Oasis® MAX) was selected as extraction sorbent. The method selectivity was not only demonstrated toward a blank plasma sample but also toward other non-steroidal anti-inflammatory drugs. The method was then successfully validated with respect to response function, trueness, precision, accuracy, linearity and limit of quantification. [source] Sorption irreversibility of 1,4-dichlorobenzene in two natural organic matter,rich geosorbentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2009Michael Sander Abstract Hysteresis, a frequently observed phenomenon in sorption studies, is inconsistent with the key assumption of sorption reversibility in most fate and bioavailability models. Therefore, a study of the underlying causes of hysteresis is essential. Carbon-radiolabeled 1,4-dichlorobenzene (DCB) isotope tracer exchange was carried out at select points along the isotherms of DCB in a brown coal and a peat soil, holding total DCB concentration constant. Tracer exchange was performed both in the forward (sorption) and reverse (desorption) directions at the bulk sorption points and in the desorption direction at the corresponding bulk desorption points. Bulk DCB isotherms showed concentration-dependent hysteresis. However, tracer reequilibration in all cases was consistent with free exchange between sorbed and aqueous-phase molecules. These results rule out common experimental artifacts and demonstrate that sorption of bulk DCB is truly hysteretic (i.e., irreversible). The differences in rates between bulk and tracer sorption and desorption are consistent with the coupling of bulk DCB diffusion to other processes that retard equilibration, which we assign to matrix swelling or shrinking. Hysteresis is attributed to matrix deformation,specifically, to inelastic expansion and creation of voids accommodating sorbate molecules in the matrix, which leads to enhanced affinity in the desorption step. Comparing the results to previous results for naphthalene in the coal, we find that irreversible effects are similar for DCB and naphthalene in the coal but differ for DCB between the two sorbents. An explanation based on the different physical properties of these sorbents is provided. Solid-phase extraction of equilibrated DCB with Tenax® revealed a highly desorption-resistant fraction. While too small to account for the observed hysteresis, this fraction may represent molecules that become trapped as the matrix collapses and simultaneously stiffens during abrupt desorption. [source] Synthesis of 18F-labeled cyclooxygenase-2 (COX-2) inhibitor as a potential PET imaging agentJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 7 2006Haibin Tian Abstract A new PET tracer for COX-2 imaging, the 6-ethoxy-3-(4-methanesulfonylphenyl)-4-(4-[18F]fluorophenyl)pyran-2-one ([18F]EFMP), was synthesized. For F-18 radiolabeling, a trimethylammonium precursor and a brominated precursor were synthesized from 1,1,2,3-tetrachlorocycloprop-2-ene in 6 steps. The radiolabeling was achieved through nucleophilic substitution using no-carrier-added (n.c.a.) fluorine-18. Solid-phase extraction and semi-preparative-HPLC purification produced [18F]EFMP in 14.6±3.3% (n =4) decay corrected radiochemical yield with a specific activity of 487±85.1 (n =4) Ci/mmol and greater than 98% radiochemical purity. Copyright © 2006 John Wiley & Sons, Ltd. [source] Solid-phase extraction and reversed-phase high-performance liquid chromatography of the five major alkaloids in Narcissus confususPHYTOCHEMICAL ANALYSIS, Issue 6 2002Susana López Abstract A novel, fast and precise method, combining solid-phase extraction and reversed-phase high-performance liquid chromatography is described for the quantitative determination of five alkaloids (galanthamine, N -formylnorgalanthamine, haemanthamine, homolycorine and tazettine/pretazettine) from bulbs of wild Narcissus confusus, a high galanthamine-containing plant species growing in the Iberian Peninsula. Copyright © 2002 John Wiley & Sons, Ltd. [source] Determination and toxicokinetics comparison of ketamine and S(+)-ketamine in dog plasma by HPLC-MS methodBIOMEDICAL CHROMATOGRAPHY, Issue 3 2010Yu-xin Sheng Abstract ;A simple and reproducible method was developed for the quantification of ketamine and S(+)-ketamine in dog plasma using a high-performance liquid chromatography system coupled to a positive ion electrospray mass spectrometric analysis. Solid-phase extraction was used for extracting analytes from dog plasma samples. The analytes were separated on a Zorbax SB C18 column (100 × 2.1 mm, 3.5 ,m) with acetonitrile,formate buffer (10 mM ammonium formate and 0.3% formic acid) (17 : 83, v/v) as mobile phase at a flow-rate of 0.2 mL/min. Detection was operated under selected ion monitoring mode. [M + H]+ at m/z 238 for ketamine and S(+)-ketamine and [M + H]+ at m/z 180 for phenacetin (internal standard) were selected as detecting ions, respectively. The method was linear in the concentration range 51.6,2580 ng/mL. The intra- and inter-day precisions (RSD %) were within 11.3% and the assay accuracies ranged from 80.0 to 101.4%. Their average recoveries were greater than 91.1% at all test concentrations. The analytes were proved to be stable during all sample storage, preparation and analysis procedures. The method was successfully applied to the toxicokinetics study and comparison of ketamine and S (+)-ketamine following intravenous administration to dogs. Copyright © 2009 John Wiley & Sons, Ltd. [source] Solid-phase extraction and analysis of paroxetine in human plasma by ultra performance liquid chromatography,electrospray ionization mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 2 2010Mitesh Bhatt Abstract A rapid, sensitive and rugged solid-phase extraction ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for determination of paroxetine in human plasma. The procedure for sample preparation includes simple SPE extraction procedure coupled with Hypersil Gold C18 column (100 mm , 2.1 mm, i.d., 1.9 ,m) with isocratic elution at a flow-rate of 0.350 mL/min and fluoxetine was used as the internal standard. The analysis was performed on a triple-quadrupole tandem mass spectrometer by multiple reactions monitoring mode via electrospray ionization. Using 500 ,L plasma, the methods were validated over the concentration range 0.050,16.710 ng/mL for paroxetine, with a lower limit of quantification of 0.050 ng/mL. The intra- and inter-day precision and accuracy of the quality control samples were within 10.0%. The recovery was 69.2 and 74.4% for paroxetine and fluoxetine respectively. Total run time was only 1.9 min. The method was highly reproducible and gave peaks with excellent chromatography properties. Copyright © 2009 John Wiley & Sons, Ltd. [source] Development and validation of a sensitive LC-MS/MS method with electrospray ionization for quantitation of pramipexole in human plasma: application to a clinical pharmacokinetic studyBIOMEDICAL CHROMATOGRAPHY, Issue 2 2009D. Vijaya Bharathi Abstract A highly sensitive and specific LC-MS/MS method has been developed and validated for the estimation of pramipexole (PPX) with 500 µL human plasma using memantine as an internal standard (IS). The API-4000 was operated under multiple-reaction monitoring mode (MRM) using the electrospray ionization technique. Solid-phase extraction was used to extract PPX and IS from human plasma. The resolution of peaks was achieved with 0.01 m ammonium acetate buffer (pH 4.4):acetonitrile (30:70, v/v) on a Discovery CN column. The total chromatographic run time was 3.0 min and the elution of PPX and IS occurred at approximately 2.32 and 2.52, respectively. The MS/MS ion transitions monitored were 212.10 , 153.10 for PPX and 180.20 , 107.30 for IS. The method was proved to be accurate and precise at linearity range of 20,3540 pg/mL with a correlation coefficient (r) of ,0.999. The intra- and inter-day precision and accuracy values found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a pharmacokinetic study in human volunteers following oral administration of 0.25 mg PPX tablet. Copyright © 2008 John Wiley & Sons, Ltd. [source] A validated new method for nevirapine quantitation in human plasma via high-performance liquid chromatographyBIOMEDICAL CHROMATOGRAPHY, Issue 1 2006Courtney F. Silverthorn Abstract A fully validated and clinically relevant assay was developed for the assessment of nevirapine concentrations in neonate blood plasma samples. Solid-phase extraction with an acid,base wash series was used to prepare subject samples for analysis. Samples were separated by high performance liquid chromatography and detected at 280 nm on a C8 reverse-phase column in an isocratic mobile phase. The retention times of nevirapine and its internal standard were 5.0 and 6.9 min, respectively. The method was validated by assessment of accuracy and precision (statistical values <15%), specificity, and stability. The assay was linear in the range 25,10,000 ng[sol ]mL (r2 > 0.996) and the average recovery was 93% (n = 18). The lower limit of quantification (relative standard deviation <20%) was determined to be 25 ng[sol ]mL for 50 µL of plasma, allowing detection of as little as 1.25 ng of nevirapine in a sample. This value represents an increase in sensitivity of up to 30-fold over previously published methods. Copyright © 2005 John Wiley & Sons, Ltd. [source] Concentration of chosen oxycholesterols in plasma of pregnant women with pregnancy-induced hypertensionBIOMEDICAL CHROMATOGRAPHY, Issue 1 2002Piotr Bodzek Solid-phase extraction (SPE) was applied for isolation of oxycholesterols from plasma lipid extract from pregnant women with hypertension and from a control group. Separation of oxycholesterols fraction was performed in an SD II horizontal chamber (Chromdes, Poland) using silica gel and octadecyl RPC18 silica gel TLC plates (Merck and Machery Nagel). Visualization was carried out under UV light after Liebermann,Burchard reaction specific for cholesterol and its derivatives. The oxycholesterols (5-cholestene-3,-ol-7-one, sum of 5-cholestene-3,, 7,-diol and 5-cholestene-3,, 7,-diol and sum of 5,,6,-epoxycholestan-3,-ol and 5,,6,-epoxycholestan-3,-ol) were quantified by chromatograms scanning in reflectance and fluorescence mode using a CS 9301 densitometer (Shimadzu). The total concentration of the investigated oxycholesterols in the plasma of pregnant women was up to 5000,ng/mL and was statistically significantly higher in women with pregnancy induced hypertension (PIH). Copyright © 2001 John Wiley & Sons, Ltd. [source] Historical review of sample preparation for chromatographic bioanalysis: pros and consDRUG DEVELOPMENT RESEARCH, Issue 3 2007Min S. Chang Abstract Sample preparation is a major task in a regulated bioanalytical laboratory. The sample preparation procedure significantly impacts assay throughput, data quality, analysis cost, and employee satisfaction. Therefore, selecting and optimizing an appropriate sample preparation method is essential for successful method development. Because of our recent expertise, this article is focused on sample preparation for high-performance liquid chromatography with mass spectrometric detection. Liquid chromatography with mass spectrometric detection (LC-MS) is the most common detection technique for small molecules used in regulated bioanalytical laboratories. The sample preparation technologies discussed are pre-extraction and post-extraction sample processing, protein precipitation (PPT), liquid,liquid extraction (LLE), offline solid-phase extraction (SPE), and online solid-phase extraction. Since all these techniques were in use for more than two decades, numerous applications and variations exist for each technique. We will not attempt to categorize each variation. Rather, the development history, a brief theoretical background, and selected references are presented. The strengths and the limitations of each method are discussed, including the throughput improvement potential. If available, illustrations from presentations at various meetings by our laboratory are used to clarify our opinion. Drug Dev Res 68:107,133, 2007. ©2007 Wiley-Liss, Inc. [source] Determination of Diclofenac in Urine Samples by Molecularly-Imprinted Solid-Phase Extraction and Adsorptive Differential Pulse VoltammetryELECTROANALYSIS, Issue 15 2007Laura Fernández-Llano Abstract A molecularly imprinted polymer for diclofenac (DCF) was prepared by thermal polymerization over silica beads using 2-(dimethylamino)ethyl-methacrylate as functional monomer. After silica elimination by HF treatment, the polymer was applied to the selective solid-phase extraction of the drug from urine followed by its quantification by adsorptive differential pulse voltammetry. Results indicate that the drug could be selectively extracted from the sample and quantified at clinically relevant concentrations (,g/mL). [source] Catalytic Voltammetric Determination of Cladribine in Biological SamplesELECTROANALYSIS, Issue 5-6 2003Noemí de-los-Santos-Álvarez Abstract An electrochemical method for the citotoxic prodrug cladribine determination is proposed. Graphite electrodes modified with cladribine showed a redox process with a formal potential of 0.173,V at pH 6, after the oxidation of the adenine moiety of the drug, whose current can be employed as analytical signal with a detection limit of 75,nM by square-wave voltammetry. As these oxidation products exhibit great electrocatalytic activity toward the electro-oxidation of NADH at low potentials, the analytical response can further be amplified. As a result, the detection limit was improved up to 1,nM using differential pulse voltammetry. The method was applied to the determination of cladribine in serum and urine samples after solid-phase extraction. No electroactive interferences were found in both fluids. The method allows the selective detection of the drug in the presence of the main metabolite, 2-chloroadenosine, which is not able to electrocatalize the NADH oxidation. [source] Preparation and evaluation of the highly cross-linked poly(1-hexadecane-co-trimethylolpropane trimethacrylate) monolithic column for capillary electrochromatographyELECTROPHORESIS, Issue 20 2009Minghua Lu Abstract In this paper, a novel highly cross-linked porous monolithic stationary phase having a long alkyl chain ligand (C16) was introduced and evaluated in CEC. The monolithic stationary phase was prepared by in situ copolymerization of 1-hexadecene, trimethylolpropane trimethacrylate, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) in the presence of ternary porogenic solvent (cyclohexanol/1,4-butanediol/water). In preparing monoliths, the ternary cross-linker trimethylolpropane trimethacrylate was usually applied to preparing molecularly imprinted polymers or molecularly imprinted solid-phase extraction, instead of binary cross-linker ethylene dimethacrylate. 1-Hexadecene was introduced to provide the non-polar sites (C16) for chromatographic retention, while AMPS was used to generate the EOF for transporting the mobile phase through the monolithic capillary. Monolithic columns were prepared by optimizing proportion of porogenic solvent and AMPS content in the polymerization solution as well as the cross-linkers. The monolithic stationary phases could generate a strong and stable EOF in various pH values and exhibit an RP-chromatographic behavior for neutral compounds. For charged compounds, the separation was mainly based on the association of hydrophobic, electrostatic and electrophoretic interaction. [source] Electrical field-assisted solid-phase extraction coupled on-line to capillary electrophoresis-mass spectrometryELECTROPHORESIS, Issue 10 2008Gabriel Morales-Cid Abstract A substantial demand currently exists for analytical methods affording the determination of very low concentrations of analytes in complex matrices, such as those of environmental and biological samples, as simply as possible. However, the pretreatment of complex samples, which is unavoidable prior to CE-MS analysis, is usually complicated and time-consuming. In this work, we used voltage-assisted SPE for the first time as an alternative to conventional treatments for preconcentrating and purifying analytes. To this end, we used a simple flow system coupled on-line to CE-MS equipment. The system is quite robust and provides reproducible peak areas (the precision ranges from 2.5 to 3.8%). Also, it provides increased sensitivity affording the determination of trace amounts (nanogram per liter levels) of analytes in only a few milliliters of sample. The proposed system was applied to the determination of members of two compound families (viz. tetracyclines and amines). [source] Combined use of supported liquid membrane and solid-phase extraction to enhance selectivity and sensitivity in capillary electrophoresis for the determination of ochratoxin A in wineELECTROPHORESIS, Issue 7 2008Sara Almeda Abstract This paper proposes a novel strategy to enhance selectivity and sensitivity in CE, using supported liquid membrane (SLM) and off-line SPE simultaneously. The determination of ochratoxin A (OA) in wine has been used to demonstrate the potential of this methodology. In the SLM step, the donor phase (either a 20,mL volume of a standard solution at pH,1 or a wine sample at pH,8) was placed in a vial, where a micromembrane extraction unit accommodating the acceptor phase (1,mL water, pH,11) in its lumen was immersed. The SLM was constructed by impregnating a porous Fluoropore Teflon (PTFE) membrane with a water-immiscible organic solvent (octanol). In the off-line SPE step, the nonpolar sorbent (C-18, 4,mg) selectively retained the target ochratoxin, enabling small volumes of acceptor phase (1,mL) to be introduced. The captured analytes were eluted in a small volume of methanol (0.1,mL). This procedure resulted in sample cleanup and concentration enhancement. The method was evaluated for accuracy and precision, and its RSD found to be 5%. The LODs for OA in the standard solutions and wine samples were 0.5 and 30,,g/L, respectively. The results obtained demonstrate that SLM combined with off-line is a good alternative to the use of immunoaffinity columns prior to CE analysis. [source] In-capillary solid-phase extraction,capillary electrophoresis for the determination of chlorophenols in waterELECTROPHORESIS, Issue 16 2006Luo-Hong Zhang Abstract A novel CE method combined with SPE in a single capillary was developed for analysis of chlorophenols in water. A frit of 0.5,mm was first made by a sol-gel method, followed by packing a SPE sorbent in the inlet end of the capillary. Two phenol derivatives, 2,4-dichlorophenol and 2,4,5-trichlorophenol, were used as the model compounds. By loading sample solutions into the capillary, the two chlorophenols were extracted into the sorbent. They were desorbed by injecting only about 4,nL of methanol. Finally, the analytes were separated by conventional CE. The technique provided a concentration enhancement factor of over 4000-fold for both chlorophenols. The detection limits (S/N,=,3) of 2,4-dichlorophenol and 2,4,5-trichlorophenol were determined to be 0.1,ng/mL and 0.07,ng/mL, respectively. For replicate analyses of 5,ng/mL of 2,4-dichlorophenol, within-day and between-day RSDs of migration time, peak height and peak area were in the range of 1.8,2.0%, 4.0,4.4% and 4.1,4.6%, respectively. The method shows wide linear range, acceptable reproducibility and excellent sensitivity, and it was applied to the analyses of spiked river water samples. The capillary packed with the SPE sorbents can be used for more than 400 runs without performance deterioration. [source] Determination of tobacco-specific N -nitrosamines in rabbit serum by capillary zone electrophoresis and capillary electrophoresis-electrospray ionization-mass spectrometry with solid-phase extractionELECTROPHORESIS, Issue 11 2006Chenchen Li Abstract In this paper, we propose a new strategy for separation and determination of tobacco-specific N -nitrosamines (TSNAs), a group of strong carcinogens found only in tobacco products, by using CZE and CE-MS associated with SPE. Six TSNAs: N'-nitrosonornicotine, N'-nitrosoanatabine, N'-nitrosoanabasine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, and 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanol were simultaneously separated by either of two CZE methods, one of which worked with ammonium formate buffer (pH,2.5) and another with citrate buffer (pH,2.4), as well as a CE-MS method. The CZE conditions including pH and concentration of running buffer, capillary length, applied voltage, and capillary temperature were systematically optimized. For CE-MS method, an optimized sheath liquid consisted of methanol,water was used at a flow rate of 10,,L/min. With SPE procedure, our proposed CE-MS method was successfully applied to determine TSNAs after 15,min metabolism in rabbits. A comparison study between CZE and CE-MS methods for quantitative purposes was carried out, showing that both methods provided similar separation efficiency, selectivity, repeatability, linearity, and recovery. However, CE-MS method was better suited for the analysis of TSNAs in complicated biological samples for its sensitivity and extra information on molecular structure. Having good accordance with our previous work by using LC-MS, the new CE-MS method is expected to be an alternative to the LC-MS method and applied to study the metabolism of TSNAs. [source] Combination of cationic surfactant-assisted solid-phase extraction with field-amplified sample stacking for highly sensitive analysis of chlorinated acid herbicides by capillary zone electrophoresisELECTROPHORESIS, Issue 18 2005Yan Xu Abstract This report describes a novel online field-amplified sample stacking (FASS) procedure to analyze 16 chlorinated acid herbicides. By using a poly(vinyl alcohol) (PVA)-coated capillary to reduce electroosmotic flow and introducing a methanol,water plug before sample loading, the sample injection time could be very long without loss of sample and separation efficiency. Under the optimized condition, the FASS procedure could provide great sensitivity enhancement (5000,10,000-fold) and satisfactory reproducibility (relative standard deviations of migration times less than 2.4%, relative standard deviations of peak areas less than 8.0%). Combined with cationic surfactant-assisted solid-phase extraction (CSA-SPE), the limit of detection of the herbicides ranged from 0.269 to 20.3,ppt, which are two orders lower than those of the US Environmental Protection Agency standard method 515.1. The CSA-SPE-FASS-CE method was successfully applied to the analysis of local pond water. [source] Nonaqueous capillary electrophoretic separation of polyphenolic compounds in wine using coated capillaries at high pH in methanolELECTROPHORESIS, Issue 24 2003Zuzana Demianová Abstract Nonaqueous capillary electrophoretic separation of a group of flavonoids (quercetin, myricetin, catechin, epicatechin) and resveratrol in wine was investigated in methanol at high pH. Malonate background electrolyte (pH* 13.5, ionic strength I = 14.2 mmol/L) provided highly repeatable separations of the analytes. Tests of untreated and coated (poly(glycidylmethacrylate- co - N -vinylpyrrolidone)) capillaries showed the analysis to be faster (6.5 min vs. 25 min) and the repeatability better in the coated capillaries. The coating procedure was simple and highly repeatable and the coating was stable during 40,45 runs. Determination of the last migrating peaks (epicatechin, resveratrol and catechin) was achieved merely by evaporating the wine samples and reconstituting the residue in methanol. For determination of the first migrating peaks (quercetin and myricetin) the samples were submitted to solid-phase extraction in C8 cartridges. [source] Determination of bupivacaine and metabolites in rat urine using capillary electrophoresis with mass spectrometric detectionELECTROPHORESIS, Issue 14 2003Ryan M. Krisko Abstract A method using capillary electrophoresis-mass spectrometry (CE-MS) was developed for the structural elucidation of bupivacaine and metabolites in rat urine. Prior to CE-MS analysis, solid-phase extraction (SPE) was used for sample cleanup and preconcentration purposes. Exact mass and tandem mass spectrometric (MS/MS) experiments were performed to obtain structural information about the unknown metabolites. Two instruments with different mass analyzers were used for mass spectrometric detection. A quadrupole time-of-flight (Q-TOF) and a magnetic sector hybrid instrument were coupled to CE and used for the analysis of urine extracts. Hydroxybupivacaine as well as five other isomerically different metabolites were detected including methoxylated bupivacaine. [source] Wastewater treatment plants as a pathway for aquatic contamination by pharmaceuticals in the Ebro river basin (Northeast Spain)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2007Meritxell Gros Abstract The occurrence of 28 pharmaceuticals of major human consumption in Spain, including analgesics and anti-inflam-matories, lipid regulators, psychiatric drugs, antibiotics, antihistamines, and ,-blockers, was assessed along the Ebro river basin, one of the biggest irrigated lands in that country. Target compounds were simultaneously analyzed by off-line solid-phase extraction, followed by liquid chromatography-tandem mass spectrometry. The loads of detected pharmaceuticals and their removal rates were studied in seven wastewater treatment plants (WWTPs) located in the main cities along the basin. Total loads ranged from 2 to 5 and from 0.5 to 1.5 g/d/1,000 inhabitants in influent and effluent wastewaters, respectively. High removal rates (60,90%) were achieved mainly for analgesics and anti-inflammatories. The other groups showed lower rates, ranging from 20 to 60%, and in most cases, the antiepileptic carbamazepine, macrolide antibiotics, and trimethoprim were not eliminated at all. Finally, the contribution of WWTP effluents to the presence of pharmaceuticals in receiving river waters was surveyed. In receiving surface water, the most ubiquitous compounds were the analgesics and anti-inflammatories ibuprofen, diclofenac, and naproxen; the lipid regulators bezafibrate and gemfibrozil; the antibiotics erythromycin, azithromycin, sulfamethoxazole, trimethoprim, and less frequently, ofloxacin; the antiepileptic carbamazepine; the antihistamine ranitidine; and the ,-blockers atenolol and sotalol. Although levels found in WWTP effluents ranged from low ,g/L to high ng/L, pharmaceuticals in river waters occurred at levels at least one order of magnitude lower (low ng/L range) because of dilution effect. From the results obtained, it was proved that WWTP are hot spots of aquatic contamination concerning pharmaceuticals of human consumption. [source] Characterization of polycyclic aromatic hydrocarbon bioavailability in estuarine sediments using thin-film extractionENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2007Christopher J. Golding Abstract It is well documented that the bioavailability of hydrophobic organic chemicals (HOCs) can vary substantially among sediments. This makes risk assessments based on total sediment concentrations problematic. The present study investigates the application of thin-film solid-phase extraction to measure bioavailable concentrations of phenanthrene in estuarine sediment by comparing concentrations of phenanthrene in the amphipod Corophium colo and in thin ethylene/vinyl acetate films at different concentrations in three geochemically different sediments. For all sediment types, concentrations of phenanthrene in sediments and thin films followed linear relationships, indicating first-order exchange kinetics. Organism/thin-film concentration ratios did not vary systematically among sediment types but dropped significantly with increasing phenanthrene concentration in the sediments. While at low phenanthrene concentrations in the sediment fugacities of phenanthrene in the amphipods approached the fugacities in the thin films, they were significantly lower than those in the sediments at higher concentrations. While phenanthrene concentrations in the three sediment types were identical, biota sediment accumulation factors and concentrations in amphipods and thin films were consistently lower in sediments enriched with black carbon than in sediments with sedimentary organic matter bearing a more diagenetic organic signature. It is concluded that, for the range of concentrations tested, thin-film solid-phase extraction can be a useful tool in the characterization of differences in bioavailability of HOCs among sediment types. [source] Identification of androstenedione in a river containing paper mill effluent,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2001Ronald Jenkins Abstract Effluent from a paper mill discharging into the Fenholloway River, Taylor County, Florida, USA, contains chemicals that masculinize females of the resident population of eastern mosquitofish (Gambusia holbrooki), as evidenced in females by elongated anal fins, which is normally a male-specific trait. To identify androgenic components in the effluent, water collected from the Fenholloway River and a control tributary was fractionated using solid-phase extraction and reverse-phase high-performanceliquid chromatography. Two Fenholloway River fractions induced androgen receptor-dependent transcriptional activity in transient transfection cell culture assays. Of these, androstenedione was confirmed by liquid chromatography-mass spectrometry with multiple reaction monitoring. [source] Phenolic compounds and some quality parameters of pumpkin seed oilEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2010Mirjana Andjelkovic Abstract Pumpkin seed oil has become a recognized source of phenolic compounds. The main aim of this paper was to evaluate the concentration of phenolic compounds and their extraction from pumpkin seed oil. The total phenolics content (TPC) measured in the pumpkin seed oil samples ranged from 24.71 to 50.93,mg GAE/kg of oil. The individual phenolics were tyrosol, vanillic acid, vanillin, luteolin and sinapic acid. Hexane and acetone were the best solvents for the washing step, and methanol for the elution of the phenolics in the solid-phase extraction (diol-SPE), whereas bleaching caused a significant increase in the TPC obtained (24.5,30.7%). Additionally, some other oil characteristics were evaluated. The mean oxidative stability of the oils (OSI) was around 4,h, with 5.43,h for the most stable oil. The maximum antioxidant capacity measured by the reduction of the DPPH radical was 62%, which was comparable to 0.16,mM Trolox equivalent. The color of the oil was expressed by L*a*b* coefficients and its hue and saturation. Whereas all samples had similar lightness, their rates of green, red, yellow and blue color were different. Moreover, TPC correlated negatively with lightness, b* and saturation (,0.49, ,0.48, and ,0.43), and positively with a* and hue (0.58 and 0.52). [source] Extracellular glycosylphosphatidylinositol-anchored mannoproteins and proteases of Cryptococcus neoformansFEMS YEAST RESEARCH, Issue 4 2007Richard A. Eigenheer Abstract Extracellular proteins of Cryptococcus neoformans are involved in the pathogenesis of cryptococcosis, and some are immunoreactive antigens that may potentially serve as candidates for vaccine development. To further study the extracellular proteome of the human fungal pathogen Cry. neoformans, we conducted a proteomic analysis of secreted and cell wall-bound proteins with an acapsular strain of Cry. neoformans. Proteins were identified from both intact cells and cell walls. In both cases, extracellular proteins were removed with trypsin or ,-glucanase, and then all proteins/peptides were purified by solid-phase extraction, spin dialysis, and HPLC, and identified by liquid chromatography,mass spectrometry. This study identified 29 extracellular proteins with a predicted N-terminal signal sequence and also a predicted glycosylphosphatidylinositol anchor motif in more than half. Among the novel proteins identified were five glycosylphosphatidylinositol-anchored proteins with extensive Ser/Thr-rich regions but no apparent functional domains, a glycosylphosphatidylinositol-anchored aspartic protease, and a metalloprotease with structural similarity to an elastinolytic metalloprotease of Aspergillus fumigatus. This study suggests that Cry. neoformans has the machinery required to target glycosylphosphatidylinositol-anchored proteins to the cell wall, and it confirms the extracellular proteolytic ability of Cry. neoformans. [source] Simultaneous determination of maraviroc and raltegravir in human plasma by HPLC-UVIUBMB LIFE, Issue 4 2009Stefania Notari Abstract Therapeutic drug monitoring is pivotal to improve the management of HIV infection. Here, a new HPLC,UV method to quantify simultaneously maraviroc and raltegravir levels in human plasma is reported. Remarkably, this is the first method for maraviroc determination in human plasma. The volume of the plasma sample was 600 ,L. This method involved automated solid-phase extraction with Oasis HLB Cartridge 1 cc (30 mg divinylbenzene and N -vinylpyrrolidone) and evaporation in a water bath under nitrogen stream. The extracted samples were reconstituted with 200 ,L 50/50 of mobile-phase solution (0.01 M KH2PO4 and acetonitrile). Twenty microliters of these samples were injected into a HPLC,UV system, the analytes were eluted on an analytical dC18 Atlantis column (150 mm × 4.6 mm I.D.) with a particle size of 5 ,m. The mobile phase (0.01 M KH2PO4 and acetonitrile) was delivered at 1.0 mL/min with isocratic elution. The total run time for a single analysis was 10 min; maraviroc and raltegravir were detected by UV at 197 and 300 nm. The calibration curves were linear up to 2,500 ng/mL. The absolute recovery ranged between 93 and 100%. The HPLC,UV method reported here has been validated and is currently applied to monitor plasma levels of maraviroc and raltegravir in HIV-infected patients. © 2009 IUBMB IUBMB Life, 61(4):470,475, 2009 [source] | ||||||||||||||||||||||||||||||||||