SEARCH · Search PubMed

Results for “Solid Phase Extraction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources

PubMed2004

Simple determination of trace amounts of anionic surfactants in river water by spectrophotometry combined with solid-phase extraction.

A simple and sensitive spectrophotometric method combined with solid-phase extraction (SPE) for the simultaneous determination of sodium linear-dodecylbenzenesulfonate (DBS) and sodium dodecyl sulfate (SDS) is described. The C2 (ethyl group bonded silicagel) cartridge could be repeatedly used more than 500 times for SPE, and it enabled the anionic surfactants to be concentrated by 50-fold. The calibration graph for DBS was linear in the range from 1.6 x 10(-8) M to 5.0 x 10(-7) M and for SDS from 2.0 x 10(-9) M to 3.0 x 10(-7) M. The relative standard deviation (n=5) for 5.0 x 10(-7) M DBS was 3.1% and for 2.5 x 10(-7) M SDS was 1.7%. The proposed method was applied to the simultaneous determination of DBS and SDS in river-water samples.

Anions↗

PubMed2006

[Simultaneous determination of twelve sulfonyl urea herbicide residues in rice by high performance liquid chromatography with solid-phase extraction].

A high performance liquid chromatographic (HPLC) method with solid-phase extraction was developed for screening of 12 sulfonyl urea herbicides in rice. The sample was cleaned up and extracted with ENVI-18 (C18) and ENVI-Carb (GCB) columns. The separation was performed on a Symmetryshield RP8 column (4.6 mm i.d. x 150 mm)with a linear gradient elution (acetonitrile and 5 mmol/L acetic acid as mobile phase), and the wavelength of an ultraviolet detector was set to 240 nm for the detection. The linear range was 0.1 - 10 mg/L, and the correlation coefficients were 0.9983-0.9999. Recoveries from rice samples spiked with 12 sulfonyl urea herbicides at spiking levels ranging from 0.01-0.50 microg/g were from 72.2% to 106.5%, with relative standard deviations from 0.6% to 6.4%. The lowest detection limits (S/N = 3) were 0.01-0.02 microg/g. The results indicate that the method is easier, faster, sensitive and has better purification effect. It also demonstrates that this multiresidue analytical method can meet the requirements for simultaneous determination of sulfonylurea herbicides in rice.

English Abstract↗

PubMed1996

Solid-phase extraction and liquid chromatographic quantitation of insect repellent N,N-diethyl-m-toluamide in plasma.

A sensitive and reliable method based on solid-phase extraction and reversed-phase liquid chromatography was developed and validated for the quantitation of insect repellent N,N-diethyl-m-toluamide (DEET) in plasma. N,N-diethyl-2-phenylacetamide was used as internal standard in the extraction which employed C18 solid-phase extraction cartridges. The wash solvent was 3 ml acetonitrile-ammonium acetate (pH 4.5; 0.03 M) (10:90, v/v), and the eluting solvent was 1 ml acetonitrile-ammonium acetate (pH 4.5; 0.03 M) (40:60, v/v). The eluent obtained from the extraction cartridge was directly analyzed on a reversed-phase C8 column with UV detection at 220 nm. A clean chromatogram and high sensitivity were achieved at this wavelength. The mobile phase was acetonitrile-ammonium acetate (pH 4.5; 0.03 M) (36:64 v/v). The retention time was 7.9 min for the internal standard and 9.6 min for DEET when the mobile phase was delivered at 1.0 ml min-1. The overall absolute recovery was 97.7% with a standard deviation (SD) of 3.9 (n = 9) for DEET and 100.2% with a SD of 3.4 (n = 3) for the internal standard. The limit of quantitation was found to be 15 ng ml-1 with a relative standard deviation of 12%. For the analyses of DEET-spiked plasma samples with five replicates each at 50, 500 and 1500 ng ml-1, the overall intra- and inter-day precisions were 5.7% and 5.5% respectively, and the overall intra- and inter-day accuracies were 2.0% and 2.4% respectively. The correlation coefficient for calibration plots in the concentration range 15-1500 ng ml-1 was typically 0.999. The method was applicable to both dog and human plasma samples and was successfully used in pharmacokinetic studies of DEET in beagle dogs after intravenous bolus and topical routes of administration.

Administration, Topical↗

PubMed2001

Molecularly imprinted solid-phase extraction sorbent for the clean-up of chlorinated phenoxyacids from aqueous samples.

A molecularly imprinted polymer (MIP) was synthesized using the herbicide 2,4,5-trichlorophenoxyacetic acid as a template, 4-vinylpyridine as an interacting monomer, ethylendimethacrylate as a cross-linker and a methanol-water mixture as a porogen. The binding properties and the selectivity of the polymer towards the template were investigated by frontal and zonal liquid chromatography. The polymer was used as a solid-phase extraction material for the clean-up of the template molecule and some related herbicides (2,4-dichlorophenoxyacetic acid, fenoprop, dichlorprop) from river water samples at a concentration level of ng/ml with quantitative recoveries comparable with those obtained with a traditional C18 reversed-phase column when analyzed by capillary electrophoresis. The results obtained show that the MIP-based approach to the solid-phase extraction is comparable with the more traditional solid-phase extraction with C18 reversed-phase columns in terms of recovery, but it is superior in terms of sample clean-up.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed2001

A 384-well solid-phase extraction for LC/MS/MS determination of methotrexate and its 7-hydroxy metabolite in human urine and plasma.

A solid-phase extraction procedure, in a 384-well format, has been developed for methotrexate and its primary metabolite, 7-hydroxymethotrexate, in human urine and plasma. This format has not been utilized previously for solid-phase extraction of drugs from biological fluids. The 384-well plates contained a C-18 stationary phase bonded to silica particles which are incorporated into a glass-fiber membrane. Methotrexate and 7-hydroxymethotrexate have been quantified across the curve range of 1 to 50 microg/mL and 50 to 1000 ng/mL, respectively, in urine and from 5 to 250 ng/mL and 5 to 100 ng/mL, respectively, in plasma. Both analytes are quantified by linear regression using 20-microL sample aliquots. Experiments to evaluate the influence of particle size, elution volume, and injection volume on signal intensity were conducted and are reported, along with the results of experiments examining cross contamination between wells. Recovery was determined to be > or = 95% from urine. Results from a run of 384 samples analyzed over a 14-h period indicate that 384-well SPE can be successfully utilized to increase analytical run sizes and sample throughput for LC/MS/MS determination of small drug molecules in biological samples.

Chromatography, Liquid↗

PubMed1996

Evaluation of a solid-phase extraction procedure for the simultaneous determination of morphine, 6-monoacetylmorphine, codeine and dihydrocodeine in plasma and whole blood by GC/MS.

Different procedures of solid-phase extraction were re-examined and a new solid-phase extraction procedure was developed using gas chromatography-mass spectrometry for the simultaneous detection and quantitation of morphine, 6-monoacetylmorphine, codeine and dihydrocodeine in plasma and whole blood. The effects of different types of sorbent and buffer solutions on the recoveries and purity of the extracts were also studied. Some preparation techniques on whole blood samples were also investigated. The method developed using Chromabond C18 (100) with spiked plasma samples had good recoveries for all opiates of interest: morphine 93.1% +/- 7.4%, 6-monoacetylmorphine 68.0% +/- 6.7%, codeine 77.0% +/- 8.3% and dihydrocodeine 67.9% +/- 8.4%. The detection limit of all compounds was less than 5 micrograms/L. The blank plasma showed no interfering peaks in the GC/MS-analysis.

Autopsy↗

PubMed2005

Integrated microfluidic device for solid-phase extraction coupled to micellar electrokinetic chromatography separation.

An integrated microdevice was utilized for the autonomous coupling of solid-phase extraction (SPE) to micellar electrokinetic chromatography (MEKC). Porous plugs of polymethacrylate polymer approximately 200 microm in length) were fabricated by ultraviolet irradiation in microchannels. Microcolumns of hydrophobic beads packed against the polymethacrylate plugs were utilized for the quantitative extraction of rhodamine B, yielding preconcentration factors over 200 for a 90-s extraction. The calculated detection limit for this dye was 60 fM. A sample of coumarin dyes were concentrated by SPE, eluted in a nonaqueous solvent from a separate on-chip reservoir, and injected by a gated valve onto a separate column for MEKC analysis. Using the integrated device, a completely automated sequence of extraction, elution, injection, separation, and detection were performed in less than 5 min. Observed separation efficiencies were high, with plate heights below 2 microm. The analysis was at least 3 times faster than semiautomated, conventional, solid-phase extraction, while requiring no user intervention. The design, fabrication, and autonomous operation of the device is discussed.

Chromatography, Micellar Electrokinetic Capillary↗

PubMedDate not supplied

Rapid screening for 100 basic drugs and metabolites in urine using cation exchange solid-phase extraction and high-performance liquid chromatography with diode array detection.

A system involving the combination of cation exchange solid-phase extraction and gradient elution HPLC with diode array detection was developed for the isolation and identification of basic drugs in urine. At least 100 basic drugs commonly encountered in urinary drug screening and many popular illicit drugs could be identified. Detailed study of 30 of these compounds showed that in addition to the procedure's simplicity and convenience, recoveries were close to 100% in most cases. The method was compared with an existing liquid-liquid extraction/capillary gas chromatography procedure and was at least as effective for extracting and identifying basic drugs, and especially effective at extracting problematic compounds including morphine, benzoylecgonine, temazepam, and oxazepam. Additional advantages of solid-phase extraction technology include the elimination of time-consuming shaking and centrifugation steps, elimination of reusable glassware, and reduced sample-operator contact with potentially infectious samples.

Cations↗

PubMed2003

Multiresidue method for fourteen fungicides in white grapes by liquid-liquid and solid-phase extraction followed by liquid chromatography-diode array detection.

A quantitative, selective and sensitive HPLC method for the analysis of 14 fungicides in white grapes for vinification is described. The proposed method is based on liquid-liquid extraction (LLE) and solid-phase extraction (SPE) followed by liquid chromatography and diode array detection (HPLC-DAD). Dichloromethane-acetone (75:25, v/v) was the most appropriate solvent mix for extracting fungicides in white grapes. Silica cartridges resulted the most appropriate for extract purification purposes. Quality parameters of the proposed multiresidue method presented good recovery (ca. 85% for almost all target compounds) and precision (between 1.5 and 16%), and detection limits lower than maxima residual limits set by the 76/895/ECC and 90/642/ECC Directive. Five different white grapes for vinification produced in Rias Baixas area in Galicia (NW Spain) were analyzed in order to assess the performance of the method with real samples and to determine whether the concentration of the pesticides used exceed their maxima residue levels (MRLs). Results showed that grape concentrations for those identified fungicides were lower than those established by European legislation.

Chromatography, High Pressure Liquid↗

PubMed2001

Solid-phase extraction of polycyclic aromatic hydrocarbons in surface water. Negative effect of humic acid.

The effect of humic acid on solid-phase extraction of polycyclic aromatic hydrocarbons (PAHs) from surface water was studied. The hydrophobic PAHs show significant association with humic acid, and this was confirmed to be the cause of negative effect when conventional reversed-phase solid-phase extraction (RP-SPE) was employed to extract the analytes from aqueous samples. As an alternative, dynamic ion-exchange (DIE) SPE could simultaneously extract both the fraction of the analytes which was associated with humic acid, and that which was freely dissolved. Using the 16 US Environmental Protection Agency priority PAHs as model compounds, the recoveries of the highly hydrophobic components by DIE-SPE were 10-30% higher than those by RP-SPE for a 1000-ml water sample dissolved with Aldrich humic acid (of 4.1 mg/l dissolved organic carbon content). A similar result was also obtained for 500 ml of natural surface water although the difference in recoveries between the two methods for this sample was smaller than that for the simulated sample. For validation of the method, the artifacts in connection with DIE-SPE in extracting the fraction of analytes which was freely dissolved and that which was associated with humic acid were investigated.

Humic Substances↗

PubMed2007

A rapid and specific approach for direct measurement of pravastatin concentration in plasma by LC-MS/MS employing solid-phase extraction.

A rapid, specific and sensitive LC-MS/MS assay using solid-phase extraction (SPE) for the determination of pravastatin, in human plasma is described. The plasma filtrate obtained after SPE, using a polymer base, a hydrophilic-lipophilic balance (HLB) cartridge, was submitted directly to short-column liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay, with negligible matrix effect on the analysis. For validation of the method, the recovery of the free analytes was compared with that from an optimized extraction method, and the analyte stability was examined under conditions mimicking the sample storage, handling, and analysis procedures. The extraction procedure yielded extremely clean extracts with a recovery of 107.44 and 98.93% for pravastatin and IS, respectively. The intra-assay and inter-assay precisions for the samples at the LLOQ were 3.30 and 7.31% respectively. The calibration curves were linear for the dynamic range 0.5-200 ng/mL with correlation coefficient r > or = 0.9988. The intra- and inter-assay accuracy ranged from 95.87 to 112.40%. The method is simple and reliable with a total run time of 3 min. This novel validated method was applied to the pharmacokinetic (PK) study in human volunteers receiving a single oral dose of 40 mg immediate release (IR) formulation.

Administration, Oral↗

PubMed2006

Development and application of a method for the analysis of N-acylhomoserine lactones by solid-phase extraction and ultra high pressure liquid chromatography.

A robust method based on solid-phase extraction (SPE) followed by ultra high pressure liquid chromatography (with trade name of Ultra Performance Liquid Chromatography: UPLC; Waters, Milford, MA, USA) is proposed for the determination of five derivatives of N-acylhomoserine lactones (AHLs) that play a biological role as signal molecules of several gram-negative bacteria. Different commercial SPE cartridges were tested for sample extraction, clean-up and preconcentration. Since the sample matrix was a complex growth media, careful optimization of the SPE with respect to washing procedure, elution solvent and sample solvent was necessary. No sample loss was observed when up to 100 mL spiked full media was added onto the cartridge. Applying UPLC for the determination of AHLs, the performance characteristics of the method showed good separation efficiency and high speed. In order to demonstrate the applicability of the method, supernatants with the known AHL producer Burkholderia cepacia LA3 grown in different media were investigated. Additionally, the method was successfully used for the degradation/uptake study of AHLs from a liquid matrix in which barley was grown under controlled condition.

4-Butyrolactone↗

PubMed2004

Chiral analysis of butaclamol enantiomers in human plasma by HPLC using a macrocyclic antibiotic (vancomycin) chiral stationary phase and solid phase extraction.

An enantioseparation of the antipsychotic drug butaclamol in human plasma by high-performance liquid chromatography (HPLC) with solid phase extraction is presented. The separation was achieved on the vancomycin macrocyclic antibiotic chiral stationary phase (CSP) Chirobiotic V with a polar ionic mobile phase (PIM) consisting of methanol : glacial acetic acid : triethylamine (100:0.2:0.05, v/v/v) at a flow rate of 0.5 ml/min. The detection wavelength was 262 nm. Bond Elut C18 solid phase extraction cartridges were used in the sample preparation of butaclamol samples from plasma. The method was validated over the range of 100-3,000 ng/ml for each enantiomer concentration (R(2) > 0.999). Recoveries for (+)- and (-)-butaclamol were in the range of 94-104% at the 300-2,500 ng/ml level. The method proved to be precise (within-run precision ranged from 1.1-2.6% and between-run precision ranged from 1.9-3.2%) and accurate (within-run accuracies ranged from 1.5-5.8% and between-run accuracies ranged from 2.7-7.7%). The limit of quantitation (LOQ) and limit of detection (LOD) for each enantiomer in human plasma were 100 ng/ml and 50 ng/ml, respectively.

Anti-Bacterial Agents↗

PubMedDate not supplied

Pretreatment of urine samples for the analysis of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid using solid-phase extraction.

An extraction and concentration procedure using a unique solid-phase extraction tube was developed for the analysis of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid in urine. Absolute and relative recoveries of the drug metabolite were found to be greater than 85% and 92%, respectively. The extraction procedure allows quantitation of the drug metabolite by GC/MS, HPLC with UV detection, or GC with flame ionization detection. The extraction procedure was verified with urine samples obtained from marijuana users as well as spiked urine samples.

Chromatography, Gas↗

PubMed2004

Development of a validated liquid chromatography method for the simultaneous determination of eight fat-soluble vitamins in biological fluids after solid-phase extraction.

In the present study, a simple and rapid reversed-phase HPLC procedure has been developed for the simultaneous determination of eight fat-soluble vitamins (retinol, menadione, menaquinone, delta-tocopherol, cholecalciferol, alpha-tocopherol, alpha-tocopherol acetate and phylloquinone) in biological fluids: blood serum and urine. The analytical column, Phenomenex Luna C18 (150 mm x 4.6 mm) 3 microm, was operating at ambient temperature. Mobile phase consisted of a mixture of CH3OH-CH3CN delivered using a linear gradient, starting with a composition of 50-50% v/v and ending at 30-70% at a flow rate of 1.3 ml/min. Xanthophyll was used as internal standard (2 ng/microl). Detection and identification was performed using a photodiode array detector. Eluent monitoring was achieved at 280 nm for vitamins and 450 nm for the internal standard. However, quantitation was performed at maximum wavelength for each vitamin. Detection limits were found in the range of 1.4-6.6 ng per 20-microl injected samples, while linearity held up to 25 ng/microl. The statistical evaluation of the method was examined performing intra-day (n = 6) and inter-day calibration (n = 7) and was found to be satisfactory, with high accuracy and precision results. The biological fluids were treated using solid-phase extraction cartridges, to remove all endogenous interferences from sample matrix. The solid-phase extraction protocol was optimized in terms of retention and elution. High extraction recoveries from biological matrices: blood serum and urine, (average recovery ranging between 95 and 97.6% for blood serum and between 94.2 and 95.8% for urine) were achieved for the eight fat-soluble vitamins, using Cyclohexyl J.T. Baker SPE cartridges with methanol as eluent, requiring small volumes, 100 microl of blood serum and 100 microl of urine.

Chromatography, High Pressure Liquid↗

PubMed2001

Determination of thiodyglycol in groundwater using solid-phase extraction followed by gas chromatography with mass spectrometric detection in the selected-ion mode.

A highly sensitive analytical procedure is described for determining thiodiglycol in groundwater. Samples are initially fortified with 3,3'-thiodipropanol (surrogate), then both species are extracted using sequential solid-phase extraction with both C18 and Ambersorb 572 columns. The C18 column, which removes extraneous groundwater components, is discarded; the Ambersorb 572 column is dried thoroughly before eluting polar components with a small volume of dichloromethane. The extract is taken to dryness using dry flowing nitrogen, and the resulting residue is derivatized using N-(tert.-butyldimethylsilyl)-N-methyltrifluoroacetamide and pyridine. The derivatized products are diluted to a final volume with toluene, chromatographed using a fused-silica capillary column, and detected with a quadrupole mass spectrometric detector in its selected-ion mode. Two independent, statistically unbiased, procedures were used to evaluate the detection limits for thiodiglycol; the values ranged between 4 and 16 microg(-1) groundwater.

Calibration↗

PubMed2004

Screening for dihydropyridine calcium channel blockers in plasma by automated solid-phase extraction and liquid chromatography/tandem mass spectrometry.

A liquid chromatographic/tandem mass spectrometric (LC/MS/MS) screening method was developed for the screening of 11 calcium channel blockers of the 1,4-dihydropyridine type in plasma samples for forensic and clinical cases. Plasma samples were extracted by automated solid-phase extraction. Analysis was performed using a reversed-phase C(18) column, gradient elution and a triple-quadrupole mass spectrometer with TurboIonSpray source in positive mode and multiple reaction monitoring. This method was found to be selective and sensitive for the detection of the target compounds at their therapeutic plasma concentrations.

Automation↗

PubMed2005

Selective quantification of trace palladium in road dusts and roadside soils by displacement solid-phase extraction online coupled with electrothermal atomic absorption spectrometry.

There is a growing concern about the effect of palladium on human health because of the toxicity and increasing occurrence of palladium as a result of its extensive use in automotive catalytic converters. Development of reliable analytical methodologies for the determination of palladium in environmental materials is of great importance for critical evaluation of the possible risks for human health. In this work, a displacement solid-phase extraction technique was developed and online coupled to electrothermal atomic absorption spectrometry (ETAAS) for selective and sensitive determination of trace palladium in environmental samples without need of any special selective complexing agents, selective sorbents, and masking agents. The developed methodology involved the online formation of copper pyrrolidine dithiocarbamate (Cu-PDC), and the resultant Cu-PDC was extracted onto a microcolumn packed with the sorbent from a cigarette filter. Trace Pd(II) was selectively preconcentrated through loading the sample solution onto the microcolumn by online displacement reaction between Pd(II) and the extracted Cu-PDC on the microcolumn. The retained analyte was subsequently eluted with 40 microL of ethanol for online ETAAS determination. Interferences from coexisting heavy metal ions with lower stability of their PDC complexes relative to Cu-PDC were minimized. The tolerable concentrations of Cd-(II), Fe(III), Co(II), Mn(II), Cr(III), and Zn(II) were up to 2, 6, 40, 2, 1.5, and at least 100 mg L(-1), respectively. Compared with conventional solid-phase extraction methodology, the developed displacement solid-phase extraction protocol gave 2-4 orders of magnitude improvement in the maximum tolerable concentrations of coexisting heavy metal ions. With the consumption of only 2.8 mL of sample solution, an enhancement factor of 52 and a detection limit (3sigma) of 18 ng L(-1) were achieved at a sample throughput of 30 samples h(-1). The precision (RSD, n = 13) was 2.5% at the 1 microg L(-1) level. The present methodology was successfully applied to selective determination of trace palladium in local road dusts and roadside soils.

Automation↗