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 613 records · Page 34Linked to original sources
PubMed2005

[Determination of residual sulfonamides in meat by high performance liquid chromatography with solid-phase extraction].

A method was developed for determining residual sulfonamides (SAs) such as sulfamethazine (SM2), sulfamonomethoxine (SMM), sulfamethiazole (SMZ), sulfadimethoxine (SDM) and sulfaquinoxaline (SQ) in pork and chicken using solid-phase extraction (SPE) and high performance liquid chromatography (HPLC) with a photodiode array detector. The samples were extracted with ethyl acetate. An NH2 column was used for clean up. For the HPLC determination, an Intersil ODS-2 column was used with a mixture of methanol-acetonitrile-water-acetic acid (2: 2: 9: 0.2, v/v) as the mobile phase. The detection limits (S/N = 3) were 3 microg/kg for SM2, SMM and SMZ, and 7 microg/kg for SDM and SQ. The quantitation limits (S/N = 10) were 10 microg/kg for SM2, SMM and SMZ, and 25 microg/kg for SDM and SQ. The linear ranges were 30 - 5 000 microg/L for SM2, SMM and SMZ, and 60 - 5 000 microg/L for SDM and SQ. The recoveries were between 73.2% and 97.3% with the relative standard deviations between 2.5% and 11.6% originated from the spiked level of 50 microg/kg.

Animals↗
PubMed2005

HPLC quantification of metoprolol with solid-phase extraction for the drug monitoring of pediatric patients.

Although the analytical literature seems abundant for the determination of metoprolol in human plasma, a method using standard equipment providing a sensitive and simple high-performance liquid chromatographic (HPLC) method for limited blood volume, e.g. where 1 mL of blood in a 1 kg infant equals 70 mL of adult blood volume, has rarely been addressed. Therefore, in 500 microL of plasma, metoprolol was extracted using an internal standard and solid-phase extraction columns. Chromatographic analysis was performed on a Spherisorb C(6) column (5 microm particle size) at ambient temperature and fluorimetric detection with an excitation wavelength of 225 nm, and emission wavelength of 310 nm. The mobile phase [30% acetonitrile and 70% 0.25 m potassium acetate buffer (pH 4)] was pumped with 1 mL/min. Metoprolol recovery was determined at 73.0 +/- 20.5%, and the limit of quantitation was 2.4 ng/mL. Precision values of intra- and inter-assay were below 15.5% and those for accuracy were between 90 and 110%. This method was developed for monitoring and determination of pharmacokinetic parameters of metoprolol in pediatric patients and therefore metoprolol plasma concentrations in a 2-year-old child with ventricular tachycardia are reported. .

Adult↗
PubMedDate not supplied

Determination of available phenolic compounds in soils by liquid chromatography with solid-phase extraction.

A fast, selective, and sensitive liquid chromatographic (LC) method was developed for determination of derivatives of benzoic and cinnamic acids (gallic, protocatechuic, 2,3,4-trihydroxybenzoic, 4-hydroxybenzoic, vanillic, caffeic, syringic, 4-coumaric, ferulic, sinapic, benzoic, 2-coumaric, cinnamic acids, and 4-hydroxybenzaldehyde and vanillin) in soil samples. The method for sample pretreatment is based on temperature-controlled extraction with water (pH 5.6) for 60 min. Extracts were preconcentrated and purified by solid-phase extraction on OASIS HLB sorbent, with subsequent separation and quantification of individual substances by LC with UV diode-array detection. Limits of detection (3 signal-to-noise LODs) better than 65 ng/g (dry weight) and recoveries from 88 to 99% were found for each compound at absorbance 280 nm. The method was used for determination of bioavailable phenolic compounds in different soil samples.

Chromatography, Liquid↗
PubMed2006

Quantifying phthalate metabolites in human meconium and semen using automated off-line solid-phase extraction coupled with on-line SPE and isotope-dilution high-performance liquid chromatography--tandem mass spectrometry.

We developed an analytical method using off-line solid-phase extraction (SPE) coupled with on-line SPE and isotope-dilution high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to determine the concentrations of phthalate metabolites in human meconium and in semen. First, we used off-line SPE to remove interfering proteins and other biomolecules from the samples. Then, we preconcentrated the phthalate metabolites in the extract using on-line SPE before measuring them by HPLC-MS/MS. For most of the analytes, the limits of detection ranged between 0.2 and 0.7 ng/g for meconium and between 0.3 and 0.7 ng/mL for semen. The recovery after off-line SPE varied for most analytes between 65 and 99% at concentrations ranging from 3.0 to 30.0 ng/mL in semen and between 67 and 103% at concentrations ranging from 2.0 to 10.0 ng/mL in meconium. Precision measured by the relative standard deviation ranged from 3.2 to 19.1% for intraday and from 3.9 to 18.6% for interday. We validated this novel approach--which is applicable to other biological matrixes, including serum and breast milk--on spiked samples and on five meconium samples and one pooled semen sample from people with no known occupational exposure to phthalates.

Animals↗
PubMed2005

Simultaneous determination of palladium, platinum, rhodium and gold by on-line solid phase extraction and high performance liquid chromatography with 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine as pre-column derivatization regents.

In this paper, 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine (HNATR) was synthesized. A new method for the simultaneous determination of palladium, platinum, rhodium and gold ions as metal-HNATR chelates was developed using a rapid analysis column high performance liquid chromatography equipped with on-line solid phase extraction technique. The samples (Water, human urine, geological samples and soil) were digested by microwave acid-digestion. The palladium, platinum, rhodium and gold ions in the digested samples were pre-column derivatized with HNATR to form colored chelates. The Pd-HNATR, Pt-HNATR, Rh-HNATR and Au-HNATR chelates can be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] with a buffer solution of 0.05 mol L(-1) phosphoric acid as mobile phase. After the enrichment had finished, by switching the six ports switching valve, the retained chelates were back-flushed by mobile phase and travelling towards the analytical column. These chelates separation on the analytical column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] was satisfactory with 72% acetonitrile (containing 0.05 mol L(-1) of phosphoric acid and 0.1% of Triton X-100) as mobile phase. The palladium, platinum, rhodium and gold chelates were separated completely within 2.5 min. Compared to the routine chromatographic method, more then 80% of separation time was shortened. By on-line solid phase extraction system, a large volume of sample (10 mL) can be injected, and the sensitivity of the method was greatly improved. The detection limits (S/N=3, the sample injection volume is 10 mL) of palladium, platinum, rhodium and gold in the original samples reaches 1.4, 1.8, 2.0 and 1.2 ng L(-1), respectively. The relative standard deviations for five replicate samples were 2.4-3.6%. The standard recoveries were 88-95%. This method was applied to the determination of palladium, platinum, rhodium and gold in human urine, water and geological samples with good results.

Chromatography, High Pressure Liquid↗
PubMed2006

Selective analysis of histamine in food by means of solid-phase extraction cleanup and chromatographic separation.

A simple, practical technique is presented for the selective determination and measurement of histamine (HA) levels in fermented food. The method involved a solid-phase extraction cleanup using a Sep-Pak Plus C-18 cartridge and ion-paired reversed-phase high-performance liquid chromatographic (IP-RP-HPLC) separation, followed by detection of HA at its UV absorbance wavelength of 220nm. After evaporating a methanolic extract from the food sample, the resulting residue was reconstituted with 0.2M phosphate buffer (pH 3.0), and subsequently passed through the cartridge. The aliquot of the solution which came out of the cartridge was chromatographed in IP-RP mode on a C-18 column, as the stationary phase, and with a solution of 0.2M phosphate buffer (pH 3.0)-acetonitrile-water (1:24:166, v/v) containing 2mM sodium 1-octane sulfonic acid, as the mobile phase. When this method was applied to a mixture of HA, Cadaverine (Cad), Putrescine (Put), Serotonin (5HT), and Tyramine (Tyr), only HA was detected at 16.4min of retention time. The method was fully validated and validation parameters were: linearity range 2-1000ppm; correlation coefficient >0.991; mean recovery >99.5%; limit of quantification 2ppm and limit of detection 0.5ppm. The method was next applied to 12 brands of Miso (fermented soybean paste), 9 brands of Sake (rice wine), and 5 brands of Shouyu (Japanese soy sauce) to verify its ability to detect the presence of HA in a variety of fermented foods. The method proved to be both rapid and accurate and is therefore recommended for use in HA pollution surveys and in the routine practice of food-quality control.

Chromatography, High Pressure Liquid↗
PubMed1999

Quantitation of efletirizine in human plasma and urine using automated solid-phase extraction and column-switching high-performance liquid chromatography.

A heart-cut column-switching, ion-pair, reversed-phase HPLC system was used for the quantitation of efletirizine (EFZ) in biological fluids. The analyte and an internal standard (I.S.) were extracted from human EDTA plasma by C18 solid-phase extraction (SPE) using a RapidTrace workstation. The eluent from the SPE was evaporated, reconstituted and injected onto the HPLC column. Urine samples were diluted and injected directly without the need of extraction. The compounds of interest were separated from most of the extraneous matrix materials by the first C18 column, and switched onto a second C18 column for further separation using a mobile phase of stronger eluting capability. Linearity range was 10-2000 ng ml(-1) for plasma and 0.05-10 microg ml(-1) for urine. The lower limit of quantitation (LOQ) was 10 ng from 1 ml of plasma, with a signal-to-noise ratio of 15:1. Inter-day precision and bias of quality control samples (QCs) were <5% for plasma and <7% for urine. Selectivity was established against six other antihistamines, three analogs of efletirizine, and on 12 control plasma lots and nine control urine lots. Recovery was 90.0% for EFZ and 89.5% for I.S. from plasma. One hundred samples can be processed in every 2.75 h on a 10-module RapidTrace workstation with minimal human attention. Method ruggedness were tested on three brands of SPE and six different lots of one SPE brand. Performance ruggedness was demonstrated by different analysts on multiple HPLC systems. Analyte stability through sample storage, extraction process (benchtop, freeze-thaw, refrigeration after extraction) and chromatography (on-system, reinjection) was established.

Acetates↗
PubMed2006

Determination of pharmaceuticals of various therapeutic classes by solid-phase extraction and liquid chromatography-tandem mass spectrometry analysis in hospital effluent wastewaters.

A multi-residue analytical method has been developed and validated for determining a selection of 16 pharmaceuticals: the anti-epileptic carbamazepine, seven analgesic/anti-inflammatory drugs (mefenamic acid, indomethacine, ibuprofen, naproxen, diclofenac, ketorolac and acetaminophen), the analgesic opiate codeine, two antidepressants (fluoxetine and paroxetine), beta-blockers (atenolol and propranolol), antibiotic (trimethoprim, metronidazole, and erythromycin) and the anti-ulcer ranitidine in hospital effluent wastewaters. The method allows simultaneous extraction of the pharmaceuticals compounds by solid-phase extraction (SPE) using the Waters Oasis HLB at pH 7. The analytes were then identified and quantitatively determined by liquid chromatography-tandem mass spectrometry (LC-MS-MS) using multiple reaction monitoring (MRM). Recoveries of the pharmaceuticals were higher than 75%, with the exception of ranitidine (45%) and the overall variability of the method was below 9%. The instrumental detection limit (IDL) varied between 2 and 31 pg injected, the method detection limit (LOD) was between 7 and 47 ng/L in spiked hospital effluent. The precision of the method, calculated as relative standard deviation (RSD), ranged from 0.3 to 4.9%. A detail study off matrix effect is included in this work, regarding to signal suppression in these effluent wastewaters from a hospital complex samples. The developed analytical method was applied for preliminary data results in effluent wastewaters from a hospital.

Adrenergic beta-Antagonists↗
PubMed1996

Solid phase extraction of 2,4-D from human urine.

A method for determining urinary concentrations of 2,4-D in samples collected from non-occupationally, environmentally exposed individuals was developed. The 2,4-D was extracted from fortified human urine samples using octadecylsilane solid phase extraction cartridges. The average percent recovery for urine samples spiked at 2 and 20 ng/mL was 100% and 93%, respectively. The method detection limit was estimated to be 0.75 ng of 2,4-D per mL of urine based on a 10 mL sample size. The potential use of 2,4-dichlorophenylacetic acid as a surrogate standard was also investigated.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2005

[Determination of the contents of resveratrols and piceids in wines by high performance liquid chromatography with solid phase extraction].

A method has been developed for the determination of the contents of cis- and trans-resveratrols and piceids in wines by high performance liquid chromatography (HPLC) with solid phase extraction (SPE). The techniques of SPE including the activation of the SPE column, elimination of interference and elution conditions of samples were confirmed. The analytes were separated by using a Hypersil C18 column (4.6 mm i. d. x 250 mm, 5 microm) and acetonitrile-water as mobile phase with linear gradient elution. A photodiode array detector monitored at the detection wavelengths of 288 nm and 306 nm for cis- and trans-isomers, respectively. The external standard calibration curves were used in quantitation. There were good linear correlations between the concentrations and peak areas of the four components with the correlation coefficients of 0.9973-0.9999. The average recoveries were 97.4%-98.6% with relative standard deviations of 2.1%-3.2%. The detection limits were 0.002-0.005 mg/L. The method of SPE-HPLC eliminated a great deal of interferences in wines effectively by optimizing extraction conditions. The four isomers were well separated and the analytical results were improved well and truly. The results for determining 15 market wines showed that as an important bioactive substance, the resveratrol content has close relationships with brewing methods, varieties of grape and producing areas. The results also showed that it is a convenient, rapid, sensitive and accurate method. It can be used to analyze resveratrols and piceids in other natural samples.

Chromatography, High Pressure Liquid↗
PubMed2004

Analysis of some cytokinins in coconut (Cocos nucifera L.) water by micellar electrokinetic capillary chromatography after solid-phase extraction.

Micellar electrokinetic capillary chromatography (MECC) was developed for the separation of cytokinins including trans-zeatin, trans-zeatin-O-glucoside, dihydrozeatin, dihydrozeatin-O-glucoside, meta-topolin riboside, N6-isopentenyladenine and N6-benzylaminopurine. Under the optimum conditions, i.e. a combination of 10 mM phosphate and 10 mM borate as the running buffer containing 50 mM sodium dodecyl sulphate at pH 10.4, the separation of seven cytokinin standards was accomplished within 11 min. The C18 solid-phase extraction (SPE) method was used to pre-concentrate the putative cytokinins present in the coconut water. Following which, the eluate was further purified using mixed mode Oasis MCX SPE columns and this additional step helps to reduce matrix interference during MECC. After the two solid-phase extraction steps, the optimized MECC method was able to screen for certain cytokinins (zeatin-O-glucoside and dihydrozeatin-O-glucoside) present in coconut water. After this screening, the presence of zeatin-O-glucoside and dihydrozeatin-O-glucoside in coconut water was further confirmed by independent high-performance liquid chromatography and liquid chromatography-mass spectrometry experiments.

Cetrimonium↗
PubMed2004

Validation and application of an automated 96 -well solid-phase extraction liquid chromatography-tandem mass spectrometry method for the quantitative determination of SCH 201781 in human plasma.

SCH 201781 is a direct thrombin inhibitor recently under study in clinical trials to determine its safety and efficacy for the treatment of venous and arterial thrombosis. In aqueous solution, SCH 201781 exists as three forms, a ring-opened hydrated form and two ring-closed diastereomers. An automated solid-phase extraction LC-MS/MS method that chromatographically separates and measures each form was developed and validated from 1 to 1000 ng/mL in human plasma. For calibration curve standards, within- and between-run precision (%CV) ranged from 0.6 to 13.7%, while accuracy (%bias) ranged from -4.8 to 13.1%. For quality control samples, within- and between-run %CV ranged from 1.5 to 9.9% while %bias ranged from -9.1 to 4.9%. The method requires a sample volume of 0.8 ml and utilizes 2H6-labeled SCH 201781 as the internal standard. For sample processing, an Isolute C-8 96-well solid phase extraction plate and a Tomtec Quadra 96 sample processor is employed. Separation of the three forms of SCH 201781 is achieved using a 5 microm, 2 mm x 100 mm Asahipak C8 HPLC column and gradient elution. A Sciex API 365 equipped with a turbo ionspray source is used in the selected reaction monitoring mode for detection. The validated method was used to support clinical studies.

Antithrombins↗
PubMed2003

Multiresidue method for determination of 90 pesticides in fresh fruits and vegetables using solid-phase extraction and gas chromatography-mass spectrometry.

A multiresidue method for analysis of 90 pesticides with different physico-chemical properties in fruits and vegetables was developed. The method involves a rapid and small-scale extraction procedure with acetone using vortex mixing. Solid-phase extraction (SPE) on a highly cross-linked polystyrene divinylbenzene column (LiChrolut EN) was used for clean-up and pre-concentration of the pesticides from the water-diluted acetone extracts. For most fruit and vegetable samples this partial clean-up was sufficient, but some of them with more co-extracting substances need further clean-up (cereals, spinach, carrots, etc.). Diethylaminopropyl (DEA) modified silica was used for efficient removal of interferences caused by various organic acids, sugars, etc. The pesticide residues were determined by gas chromatography with a mass selective detector (GC-MS). The majority of pesticide recoveries for various fruits and vegetables were >80% in the concentration range from 0.01 to 0.50 mg/kg, except for the most polar pesticides (methamidophos, acephate, omethoate) which cannot be determined by this method. The limit of quantitation for most of the pesticides was 0.01 mg/kg with majority of relative standard deviations (R.S.D.s) below 10%.

Calibration↗
PubMed2006

Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its ion-association complex with cetyltrimethylammoniumbromide on an alumina column.

A simple approach has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its ion-association complex with cetyltrimethylammoniumbromide (CTABr) on an alumina column. The effect of various parameters such as acidity, stability of the column, sample volume, effect of diverse ions, etc. have been studied in detail. The adsorbed complex could be eluted using sodium hydroxide and the concentration of chromium has been established using visible spectrophotometry after complexation with diphenyl carbazide. The calibration graph was linear in the range 0-0.5 microg mL(-1) chromium(VI) with a detection limit of 5 microg L(-1). A highest preconcentration factor of 25 could be obtained for 250 mL sample volume. The data from the column studies were also studied using the Thomas model of adsorption. The experimental results obtained were correlated with the proposed model of adsorption. The Thomas rate constant k was found to be 0.0025 L/min mg and the maximum adsorption capacity q(o) was found to be 0.36 mgCr/g alumina at an initial chromium(VI) concentration of 1 mg L(-1). The validity of the method has been checked by applying it to study the recovery of chromium in spiked water samples and electroplating wastewater.

Adsorption↗
PubMed2006

[Analysis of pesticide multiresidues in rice by gas chromatography-mass spectrometry coupled with solid phase extraction].

A new analytical method was developed to simultaneously determine multiple pesticide residues in rice including organophosphorus, organochlorine, carbamate and pyrethroid. First, the solvents for pesticide extraction were selected for optimization. Eight solvents were screened to find that the extraction efficiency with dichloromethane was the best. Second, clean-up was performed by solid phase extraction using a Florisil cartridge. Various mixtures of hexane and acetone were tested to show that the mixture of hexane-acetone (4:1, v/v) had the best performance. The clean-up helped the sample purification significantly. The prepared sample was analyzed using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. The pesticides were identified with retention time and selected ions and their relative abundances, and they were quantified based on extract of spiking standards in a blank sample. The limits of detection (LODs) were evaluated on the values of the lower concentration fortified sample under the signal-to-noise ratio of 3:1. The recoveries and relative standard deviations (RSDs) were checked by adding pesticide standard solution at two levels to untreated samples, and the triplicate analysis of the samples were carried out for each spiked level. The LODs were at microg/kg level. The average recoveries of most pesticides were from 75% to 120 %. The RSDs were less than 10.4% (n = 3). These results indicated that this method is simple, rapid, sensitive for the simultaneous determination requirements of multiple pesticide residues in rice.

Food Contamination↗
PubMed2002

Determination of isoxaflutole (balance) and its metabolites in water using solid phase extraction followed by high-performance liquid chromatography with ultraviolet or mass spectrometry.

Balance (isoxaflutole, IXF) belongs to a new family of herbicides referred to as isoxazoles. IXF has a very short soil half-life (<24 h), degrading to a biologically active diketonitrile (DKN) metabolite that is more polar and considerably more stable. Further degradation of the DKN metabolite produces a nonbiologically active benzoic acid (BA) metabolite. Analytical methods using solid phase extraction followed by high-performance liquid chromatography-UV (HPLC-UV) or high-performance liquid chromatography-mass spectrometry (HPLC-MS) were developed for the analysis of IXF and its metabolites in distilled deionized water and ground water samples. To successfully detect and quantify the BA metabolite by HPLC-UV from ground water samples, a sequential elution scheme was necessary. Using HPLC-UV, the mean recoveries from sequential elution of the parent and its two metabolites from fortified ground water samples ranged from 68.6 to 101.4%. For HPLC-MS, solid phase extraction of ground water samples was performed using a polystyrene divinylbenzene polymer resin. The mean HPLC-MS recoveries of the three compounds from ground water samples spiked at 0.05-2 microg/L ranged from 100.9 to 110.3%. The limits of quantitation for HPLC-UV are approximately 150 ng/L for IXF, 100 ng/L for DKN, and 250 ng/L for BA. The limit of quantitation by HPLC-MS is 50 ng/L for each compound. The methods developed in this work can be applied to determine the transport and fate of Balance in the environment.

Chromatography, High Pressure Liquid↗
PubMed2001

On-line extraction using an alkyl-diol silica precolumn for racemic citalopram and its metabolites in plasma. Results compared with solid-phase extraction methodology.

Sample preparation is usually the most critical and time consuming step when using HPLC for drug analysis in biological matrixes. Sample extracts have to be clean considering both chromatographic interferences and column maintenance. To meet some of these criteria a fully automated on-line extraction (OLE) analysis method was developed for the antidepressant drug citalopram and its two demethylated metabolites, using an RP-C4-ADS extraction column. A comparison between the new OLE method and an off-line solid-phase extraction method showed that the two methodologies were equal in analytical precision but that the OLE method was faster and therefore superior in sample capacity per day.

Antidepressive Agents, Second-Generation↗
PubMed2006

Determination of cadmium and zinc in fertilizer samples by FAAS after solid-phase extraction with freshly precipitated manganese-diethyldithiocarbamate.

Using freshly precipitated manganese-diethyldithiocarbamate (Mn(DDTC)(2)) as a new reagent, a solid phase extraction method (SPE) has been developed for the extraction of Cd(II) and Zn(II) in aqueous fertilizer samples. A sample solution of 300 mL was taken and 0.10 g of freshly precipitated Mn(DDTC)(2) was added. After adding a phosphate buffer solution, the mixture was stirred at 10 min, filtered with a glass filter and washed with deionized water. The solid product containing Mn(DDTC)(2)-Cd(DDTC)(2)-Zn(DDTC)(2) complexes was dissolved in concentrated nitric acid and its volume was made complete up to 10 mL with deionized water. The metal contents of the solution were measured by an atomic-absorption spectrometer.

Journal Article↗