Search PubMed⌕ Search

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.

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

At least 1,171 records · Page 65Linked to original sources
PubMed2000

Novel use of a dual-zone restricted access sorbent: normal-phase solid-phase extraction separation of methyl oleate from polynuclear aromatic hydrocarbons stemming from semi-permeable membrane devices.

A normal-phase solid-phase extraction (SPE) method was developed utilizing a dual-zone restricted-access sorbent to separate methyl oleate from the 16 US Environmental Protection Agency priority-pollutant polynuclear aromatic hydrocarbons in a hexane matrix. This technique represents a new development in SPE methodology expanding the limited number of available normal-phase SPE sorbents. While based on a specific application (removal of methyl oleate from semipermeable membrane device extracts), this cleanup method could easily be adapted for other uses requiring the removal/isolation of methyl oleate and potentially related compounds.

Chromatography, Gas↗
PubMed2003

Fast fractionation of complex organic extracts by normal-phase chromatography on a solid-phase extraction polymeric sorbent. Optimization of a method to fractionate wine flavor extracts.

Some properties of LiChrolut-EN resins as normal-phase sorbent have been studied. Retention factors using pentane as solvent range from less than 2 (ethyl esters) to more than 56 (fatty acids and vanillin). All retention factors were smaller than 2 with dichloromethane. The efficiency of the bed was between 4 and 13 plates per cm. A method for the fast fractionation of wine flavor extracts has been further developed. Wine (75 ml) is extracted on a 0.5 g LiChrolut-EN bed. Volatile compounds are recovered in 5 ml of dichloromethane and the extract is further concentrated to 0.1 ml. Recoveries of the extraction procedure are above 85% for all compounds less polar than isoamyl alcohol. This extract is fractionated on a bed (5.0 cm height, 0.6 cm internal diameter) packed with 0.55 g of LiChrolut-EN resins. A first fraction is collected by the elution with 4 ml of pentane. A second one with 6 ml of a mixture pentane/dichloromethane (9:1) and a final fraction with 4 ml of dichloromethane. The first fraction is enriched in ethyl esters and some other non-polar compounds. The second fraction concentrates the alcohols and some volatile phenols, while the third is enriched in fatty acids, vanillin derivatives and some lactones. The recovery in the fractionation is complete. The profile obtained in the fractionation is very stable, and becomes distorted only when the column is loaded with an extract containing 80 mg of major volatiles (coming from more than 150 ml of wine). The fractionation of extracts from different wines showed that the performance of the process does not depend on the composition of the extract. Twenty-seven out of 32 studied compounds eluted reproducibly mainly in one fraction. The results suggest that the method can be applied as an aid for qualitative or quantitative analysis to any kind of organic extract as an alternative to liquid chromatography on silica-gel.

Chromatography, Liquid↗
PubMed2001

Use of molecularly imprinted polymers in the solid-phase extraction of clenbuterol from animal feeds and biological matrices.

Clenbuterol molecularly imprinted polymers (MIPs) as chromatographic stationary phase for the solid-phase extraction (SPE) of the drug from biological samples have been prepared. Propylene columns filled with 500 mg of clenbuterol MIPs have been tested with respect to their loading capacity, memory effects, selectivity toward related drugs (mabuterol, clenproperol, clenisopenterol, ritodrine) and specificity toward interferences arising from heterogeneous matrices such as animal feeds, bovine urine and liver. Analytes were concentrated on Extrelut 20 columns and the residues resuspended in 70% acetonitrile. Application, washing and elution fractions were collected and analyzed by HPLC-diode array detection. Results indicate this MIP approach in SPE is extremely selective for clenbuterol, mabuterol, clenproperol and clenisopenterol (>95% found in the eluate), with a loading capacity of about 20 microg/100 mg of stationary phase. Ritodrine showed a recovery rate of 51%. The molecular recognition mechanism is so specific to allow clenbuterol detection and identification by conventional detectors at level of interest (ppb) also from complex matrices such as feeds, urine and liver.

Adrenergic beta-Agonists↗
PubMedDate not supplied

Determination of basic drugs extracted from biological matrices by means of solid-phase extraction and wide-bore capillary gas chromatography with nitrogen-phosphorus detection.

Determination of basic drugs from biological matrices at concentration levels of 100-200 ng/mL was accomplished by using mixed-mode Bond Elut Certify columns and a gas chromatograph equipped with a nitrogen-phosphorus detector. The extraction procedure developed for general drug screening on a GC-FID system was found suitable for the extraction of basic drugs from plasma and whole blood for GC-NPD analysis. For urine samples, an extra wash step with 20% acetonitrile in water was required to obtain clean extracts. The recoveries of 18 basic drugs ranged from 77.7 to 104.5%, with relative standard deviations less than 7.0%.

Animals↗
PubMed1997

[Solid phase extraction and high performance liquid chromatographic determination of enalapril in human plasma].

A reversed phase high performance liquid chromatographic method utilizing solid phase extraction has been described for the determination of enalapril in human plasma. The C18 sorbent cartridges were conditioned and plasma samples were applied, washed with 20 mmol.L-1 HCl (2 x 0.5 ml) and petroleum ether (boiling range 60-90 degrees C) subsequently; and eluted with methanol (3 x 0.5 ml). The eluent was evaporated to dryness, reconstituted in 100 microliters mobile phase and injected. Chromatographic separation was achieved on a Spherisorb C8 column (200 mm x 4.6 mm, 5 microns), with ethanol--water--10% H3PO4--triethylamine (30:70:1.5:0.1) at a flow rate of 1.0 ml.min-1. UV detection was set at 215 nm. The calibration ranges were 2.5-150 ng.ml-1 with regression coefficient of 0.997 and detection limit of 1.5 ng.ml-1. The within-day RSD and between-day RSD were < 8.73%, the recovery of method > 91.6%. This method was applied to the pharmacokinetic analysis of enalapril in 8 human volunteers.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2002

Use of semi-permeable membrane devices and solid-phase extraction for the wide-range screening of microcontaminants in surface water by GC-AED/MS.

An automated GC-MS-based screening method was developed for over 400 industrial, agrochemical and household chemicals. Extracted ion chromatograms were used and the method was aimed at creating a minimum number of false positives. The compound polarity range usually associated with solid-phase extraction was extended to include very apolar, bioaccumulative, compounds by using the complementary semi-permeable membrane device technique. Real-life samples were taken at four locations in the main Dutch river systems and one in an agricultural area. Some 150 compounds were detected in the low-ng/l to low-microg/l range. Next to the target compounds, several brominated and chlorinated non-target compounds were detected by means of GC with atomic emission detection and tentatively identified using mass spectral library searching.

Automation↗
PubMedDate not supplied

Measurement of theophylline metabolites produced by reaction with hepatic microsome by high performance liquid chromatography following solid phase extraction.

An analytical method has been developed with which to measure the microsomal enzyme activities responsible for oxidative theophylline metabolism. Three metabolites: 3-Methylxanthine (3-MX); 1-methylxanthine (1-MX); 1,3-dimethyluric acid (1,3-DMU), with acetaminophen as an internal standard (IS), were separated by solid phase extraction using a Sep-Pak C18 cartridge, followed by high performance liquid chromatography on a reversed-phase column with isocratic elution using 25 mM acetate buffer containing 4% acetonitrile and 2.5 mM tetra-n-butylammonium hydrogen sulphate (pH 5.25) as the mobile phase. The analytes were clearly resolved and no interference with foreign peaks was observed. A linear relationship was obtained for the metabolites over the concentration range of 0.5-5.0 micrograms/mL, and their analytical recovery was almost 100%. This method can be used to assess drug interactions involving alterations in the biotransformation of theophylline.

Animals↗
PubMed2002

Simultaneous determination of metabolites of trimethylbenzenes, dimethylbenzylmercapturicacid and dimethylhippuric acid, in human urine by solid-phase extraction followed by liquid chromatography tandem mass spectrometry.

We describe a novel method for the determination of three kinds of dimethylbenzylmercapturic acids (DMM) and six kinds of dimethylhippuric acids (DMH), found in urine as metabolites of trimethylbenzenes, based on liquid chromatography/electrospray ionization tandem mass spectrometry. A solid-phase extraction procedure was used for the extractions of DMM and DMH from a urine sample, and the separation was performed on a reversed-phase C(30) column. The analytes were ionized by electrospray in the positive-ion mode. Operating in the multiple reaction monitoring mode, the linearity of the relative mass spectrometric responses to the internal standard versus analyte concentrations were established in the range 0.1-100 ng ml(-1). The extraction procedure was rapid and the relative standard deviations were below 5%. The detection limits of DMM and DMH in the urine by the proposed method were in the ranges 0.26-0.41 and 0.42-2.0 ng l(-1), respectively. Furthermore, DMM and DMH were detected in a urine sample from an individual who did not suffer from occupational exposure to trimethylbenzenes, by using this method.

Acetylcysteine↗
PubMed2005

Determination of pesticides and PCBs in honey by solid-phase extraction cleanup followed by gas chromatography with electron-capture and nitrogen-phosphorus detection.

A multiresidue method for determination of 15 organochlorine pesticides (OCPs), six polychlorinated biphenyls (PCBs), and seven organophosphorus pesticides (OPPs) is implemented for routine determinations of residues in honey. The method involves solid-phase extraction cleanup and determination by GC-ECD/NPD. Quantitation limits ranged from 0.1 to 0.6 microg kg-1 honey for OCPs and PCBs, and from 5.0 to 25.0 microg kg-1 honey for OPPs. Recoveries of OCPs ranged between 77.4 and 94.0%; for PCBs they were from 63.8 to 73.5%. Recovery assays for OPPs varied from 66.7 to 98.1%. The method was applied to the analysis of 111 honey samples from Aragon, Spain. The results obtained indicated a low level of contamination by pesticide residues and PCBs, which can contribute to ensuring the consumer has a safe wholesome supply of honey.

Calibration↗
PubMed1992

Determination of benzene metabolites in urine of mice by solid-phase extraction and high-performance liquid chromatography.

A method was developed for quantitative measurement of trans,trans-muconic acid, catechol, hydroquinone and phenol in urine. Hydrolysis of esterified and glucuronized phenolic compounds was effected by specific enzymes. The hydrolysed mixture was purified and separated by solid-phase extraction with an anion exchanger, followed by extraction with diethyl ether. By using a clean-up procedure the natural background from mouse urine could be reduced, so that the detection limit of the metabolites was in the range 3-60 mg/l. Optimization of the chromatographic conditions resulted in a short high-performance liquid chromatography analysis time. Phenol had the longest retention time of about 10 min. The clean-up procedure could also be used for phenylmercapturic acid, an additional benzene metabolite, but for sensitive high-performance liquid chromatographic detection of phenylmercapturic acid other conditions are necessary.

Animals↗
PubMed1991

Determination of p-methylthiobenzamide and p-methylthiobenzamide-S-oxide from rat plasma using solid-phase extraction and high-performance liquid chromatography.

p-Methylthiobenzamide (PMTB) is a thiocarbonyl compound exhibiting marked hepatotoxicity and nephrotoxicity. We describe a high-performance liquid chromatographic method for analyzing PMTB and a metabolite, p-methylthiobenzamide-S-oxide (PMTBSO), from rat plasma using a solid-phase extraction technique. In this way, PMTB and PMTBSO can be extracted from 0.5 ml of plasma and separation achieved by an ODS analytical column in as little as 9 min. The mobile phase used was methanol-water (55:45, v/v) and the wavelength for detection was 290 nm. The limits of detection in plasma were 15 ng/ml for PMTB and 33 ng/ml for PMTBSO; the absolute recovery from spiked plasma samples was greater than 84.4% for both compounds and the internal standard. The method was linear throughout the range used with correlation coefficients greater than 0.969. The intra-day accuracy ranged from 1.52 to 15.23% relative error for the PMTB concentration range 151-3025 ng/ml; accuracy of 4.97% or less was obtained for PMTBSO concentrations of 1672-20,068 ng/ml. The intra-day precision (coefficient of variation) of the procedure was found to be no greater than 5.28% for PMTB and 7.9% for PMTBSO. Inter-day accuracy and precision measurements were similar.

Animals↗
PubMed2006

Flow injection on-line solid phase extraction coupled with inductively coupled plasma mass spectrometry for determination of (ultra)trace rare earth elements in environmental materials using maleic acid grafted polytetrafluoroethylene fibers as sorbent.

A new sorbent, maleic acid grafted polytetrafluoroethylene fiber (MA-PTFE), was prepared and evaluated for on-line solid-phase extraction coupled with inductively coupled plasma mass spectrometry (ICP-MS) for fast, selective, and sensitive determination of (ultra)trace rare earth elements (REEs) in environmental samples. The REEs in aqueous samples at pH = 3.0 were selectively extracted onto a microcolumn packed with the MA-PTFE fiber, and the adsorbed REEs were subsequently eluted on-line with 0.9 mol l(-1) HNO3 for ICP-MS determination. The new sorbent extraction system allows effective preconcentration and separation of the REEs from the major matrix constituents of alkali and alkali earth elements, particularly their separation from barium that produces considerable isobaric interferences of 134Ba16O1H+, 135Ba16O+, 136Ba16O1H+, and 137Ba16O+ on 151Eu+ and 153Eu+. With the use of a sample loading flow rate of 7.4 ml min(-1) for 120 s preconcentration, enhancement factors of 69-97 and detection limits (3s) of 1-20 pg l(-1) were achieved at a sample throughput of 22 samples h(-1). The precision (RSD) for 16 replicate determinations of 50 ng l(-1) of REEs was 0.5-1.1%. The developed method was successfully applied to the determination of (ultra)trace REEs in sediment, soil, and seawater samples.

Journal Article↗
PubMed2005

Determination of glabridin in human plasma by solid-phase extraction and LC-MS/MS.

Glabridin is a major flavonoid included specifically in licorice (Glycyrrhiza glabra L.), and has various physiological activities including antioxidant and anti-inflammatory effects. We have developed and validated an analytical method for determination of glabridin in human plasma by solid-phase extraction (SPE) and LC-MS/MS. Glabridin was extracted from plasma by SPE using a C8 cartridge and analyzed by LC-MS/MS using mefenamic acid as an internal standard (IS). The analyte were separated by a C18 column on LC, and monitored with a fragment ion of m/z 201 formed from a molecular ion of m/z 323 for glabridin and that of m/z 196 from m/z 240 for IS during negative ion mode with tandem MS detection. The lower limit of quantitation (LLOQ) of glabridin was 0.1 ng/mL in plasma, corresponding to 1.25 pg injected on-column. The calibration curves exhibited excellent linearity (r>0.997) between 0.1 and 50 ng/mL. Precision and accuracy were <17 and <+/-7% at LLOQ, and <11 and <+/-5% at other concentrations. Glabridin was recovered >90%, and was stable when kept at 10 degrees C for 72 h, at -20 degrees C until 12 weeks, and after three freeze-thaw cycles. This is the first report on determination of glabridin in body fluids by the selective, sensitive, and reproducible method.

Chromatography, Liquid↗
PubMed2005

Determination of atazanavir in human plasma using solid-phase extraction and high-performance liquid chromatography.

Atazanavir is a new HIV-1 protease inhibitor. A simple high-performance liquid chromatographic method using UV detection was developed and validated for the analysis of atazanavir in human plasma. The sample clean up was carried out using solid-phase extraction with OASIS MCX cartridge. The chromatographic separation was achieved on a Kromasil C18 (150 mm x 3 mm, 5 microm) column with a mobile phase consisting of acetonitrile and water (38:62 v/v) delivered isocratically. The effluent of the column was monitored at a wavelength of 210 nm. The assay was linear over the concentration range of 0.156 to 10 microg/ml and the limit of quantification was 0.156 microg/ml. The method was also validated with respect to recovery, precision, accuracy and specificity. This method is suitable for therapeutic drug monitoring of atazanavir and can be easily reproduced with standard equipment.

Acetonitriles↗
PubMed1997

Simultaneous determination of a novel anticancer drug, TAS-103, and its N-demethylated metabolite in monkey plasma by high-performance liquid chromatography using solid-phase extraction.

A simple and rapid method for the analysis of a novel anticancer drug, TAS-103, and its metabolite demethyl-TAS-103 in monkey plasma has been developed. This method is based on high-performance liquid chromatography with visible detection at 460 nm after solid-phase extraction with a Sep-Pak Vac PS-2 cartridge. The extraction recoveries of each compound, including the internal standard TAS-1-1018, were from 88 to 102%. The quantitation limit of each compound was 5.0 ng/ml in 0.5 ml of plasma. The coefficients of variation for each compound ranged from 0.9 to 4.9%, and relative errors for each compound ranged from -3.8 to 4.6%. Both compounds in monkey plasma were stable at -80 degrees C for 39 days and the extracts were stable at ambient temperature for 24 h. This method has been demonstrated to be useful for the pharmacokinetic study of TAS-103 in monkey plasma after intravenous administration.

Aminoquinolines↗
PubMedDate not supplied

Multiresidue determination of pesticides in drinking and related waters by solid-phase extraction and liquid chromatography with ultraviolet detection: interlaboratory study.

As part of a project funded by the European Commission (EC) for the development and evaluation of multiresidue methods for analysis of drinking and related waters, 17 European laboratories evaluated a method using styrene-divinylbenzene copolymer solid-phase extraction followed by liquid chromatography with diode array detection. The main aim of the study was to evaluate whether the method meets the requirements of EC Drinking Water Directive 98/83 in terms of accuracy, precision, and detection limit for 21 pesticides according to the following requirements: limit of detection, < or =0.025 microg/L; accuracy expressed as recovery, between 75 and 125%; and precision expressed as repeatability relative standard deviation of the method, <12.5%, and as reproducibility relative standard deviation of the method, <25%. Analyses for unknown concentrations were performed with commercial bottled and tap waters. All laboratories were able to achieve detection limits of 0.01 microg/L for all pesticides except pirimicarb (0.02 microg/L). The criteria for repeatability were met for all compounds. Terbutryn in bottled water and carbendazim in tap water did not meet the criteria for reproducibility. In terms of accuracy, the method met the requirements for all pesticides in both matrixes, except for metamitron. However, several compounds (linuron, terbutryn, propazine, metobromuron, and isoproturon) showed recoveries slightly below 75%.

Chromatography, Liquid↗
PubMed1995

Sensitive assay for measuring amoxicillin in human plasma and middle ear fluid using solid-phase extraction and reversed-phase high-performance liquid chromatography.

We developed a sensitive assay to measure amoxicillin in human plasma and middle ear fluid (MEF) using solid-phase extraction and reversed-phase HPLC. Amoxicillin and cefadroxil, the internal standard, were extracted from 50-200 microliters of sample with Bond Elut C18 cartridges. The extract was analyzed on a 15 cm x 2 mm, 5 micron Keystone MOS Hypersil-1 (C8) column with UV detection at 210 nm. The mobile phase was 6% acetonitrile in 5 mM phosphate buffer (pH = 6.5) and 5 mM tetrabutylammonium. The average absolute recovery of amoxicillin and cefadroxil were 91.2 +/- 16.6% and 91.0 +/- 6.8%, respectively. The limit of quantitation was 0.125 microgram/ml with 200 microliters sample size. The linear range was from 0.125 to 35.0 micrograms/ml with correlation coefficients greater than 0.999. These analytic conditions produced a highly sensitive amoxicillin assay in human body fluids without derivatization.

Acetonitriles↗
PubMed1991

NMR-monitored solid-phase extraction of phenolphthalein glucuronide on phenylboronic acid and C18 bonded phases.

Preliminary studies have been undertaken to evaluate the potential of immobilized phenylboronic acid (PBA) for the solid-phase extraction (SPE) of glucuronide metabolites from urine. These studies have demonstrated that immobilized PBA can be used to specifically extract phenolphthalein glucuronide (5 mM) from urine. Urine samples were loaded onto the PBA SPE column in glycine buffer (pH 8.5) and were eluted using methanol-1% HCl (90:10, v/v). The overall recoveries of the phenolphthalein glucuronide for this procedure were high (99%), which compared well with similar studies carried out concomitantly on C18 bonded columns (93%).

Boronic Acids↗