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PubMed1996

Solid phase extraction of morphine and its metabolites from postmortem blood.

A simple and rapid high-performance liquid chromatographic method is described for the determination of morphine-3-glucuronide, morphine-6-glucuronide, normorphine and morphine in postmortem blood. A solid phase extraction technique employing C18 Sep-Pak cartridges was used to recover morphine and its metabolites from 0.5 ml of blood. Reverse phase ion-pair chromatography was used to achieve separation with a C18 bonded column. The mobile phase consisted of acetonitrile, lauryl sulphate and sodium dihydrogen orthophosphate buffer at low pH. Electrochemical detection (ECD) in series with ultraviolet (UV) spectrophotometric detection (210 nm) was used for quantitation. The lower limit of detection using ECD was 10 ng/ml for all analytes and a linear response was observed to 5000 ng/ml. Coefficients of variation for all analytes ranged between 3-13% for both intra- and inter-assay. This method is reproducible, quick and easy to perform and allows morphine conjugates and morphine to be measured simultaneously in postmortem blood.

Adult↗
PubMed2005

Sequential-injection determination of traces of disodium phenyl dibenzimidazole tetrasulphonate in urine from users of sunscreens by on-line solid-phase extraction coupled with a fluorimetric detector.

A sensitive and selective method to determine disodium phenyl dibenzimidazole tetrasulphonate (PDT) in the urine of sunscreen users, which is suitable for studies on body accumulation/excretion is proposed. On-line solid-phase extraction allows the analyte to be retained and subsequentely eluted, using a strong anion exchange (SAX) microcolumn. Standard addition calibration was carried out with only one standard. The wavelengths of excitation and emission were 330 and 454 nm, respectively. The method allows PDT to be determined in both, spiked and unspiked human urine samples, without any pre-treatment. Results obtained for spiked urine samples (40-200 ng ml(-1)) showed the accuracy of the method. The mean relative standard deviations (R.S.D.) of the results was 7%. Five volunteers applied a sunscreen lotion containing 5% PDT and their urinary excretion was controlled from the moment of application until the excreted amounts were no longer detectable. The sensitivity of the proposed method is in the order of 1900 ml microg(-1) and the detection limit (3S(y/x)/b) is in the order of 5 ng of PDT, which means 10 ng ml(-1) for a 500 microl injected volume, and this is suitable for the PDT levels found in the urine.

Administration, Topical↗
PubMed2000

Solid-phase extraction with a dibutylmelamine-imprinted polymer as triazine herbicide-selective sorbent.

Triazine herbicide-selective polymer spheres were prepared by molecular imprinting using dibutylmelamine (DBM) as a template in suspension polymerization, and were utilized in solid-phase extraction (SPE) of atrazine. Atrazine-selective SPE was successfully demonstrated with a recovery of ca. 97% and an enrichment factor of 50, proving the good aptitude of DBM as the template species for developing a specific sorbent for triazine herbicides. It is also noteworthy that DBM-imprinted polymers have no possibility of disturbance in agrochemical analyses even if DBM remained in the polymer, which may occur by insufficient washing at the stage of removing the template to yield the binding sites, increasing the availability of imprinted polymers for practical applications.

Chemistry Techniques, Analytical↗
PubMed2000

Solid-phase extraction of polar hydrophilic aromatic sulfonates followed by capillary zone electrophoresis-UV absorbance detection and ion-pair liquid chromatography-diode array UV detection and electrospray mass spectrometry.

A comprehensive comparison of four different polymeric solid-phase extraction (SPE) materials for the extraction of 22 different aromatic sulfonates of environmental concern was performed. The investigated adsorbents were the polystyrene-divinylbenzene materials LiChrolut EN from Merck, Isolute ENV+ from International Sorbent Technology, HR-P from Macherey-Nagel and the new Oasis HLB poly(divinylbenzene-co-N-vinylpyrrolidone) copolymer from Waters. Different SPE parameters like the elution solvent and the drying step of the cartridges were optimized. Analyses were performed by capillary zone electrophoresis-UV absorbance detection (CZE-UV) and ion-pair liquid chromatography-diode array UV detection coupled in series with electrospray mass spectrometry (IP-LC-DAD-ESI-MS) in the negative ionization mode. LC-MS offers a higher separation efficiency than CZE. The best adsorbents were LiChrolut EN and HR-P followed by Isolute ENV+ and Oasis HLB. The recoveries for most of the onefold negatively charged aromatic sulfonates were >50% for the extraction from spiked ground water at 50 microg/l. Recoveries for LiChrolut EN and HR-P were approximately 20% higher than for Isolute ENV+. Very hydrophilic sulfonates containing more than one negative sulfonate group could not be extracted by any of the tested adsorbents.

Calibration↗
PubMed1989

Determination of pioglitazone in dog serum using solid-phase extraction and high-performance liquid chromatography with ultraviolet (229 nm) detection.

An analytical method is described for the determination of the free base of pioglitazone hydrochloride (U72, 107A, AD-4833) in dog serum. The method used solid-phase extraction of pioglitazone from serum followed by high-performance liquid chromatographic analysis on an octadecylsilane column with an eluent of acetonitrile-water (41:59, v/v) containing 1.2 ml/l acetic acid (pH 6.0 +/- 0.05). The column effluent was monitored at 229 nm. The analytical procedure has a linear range of 25 ng/ml to 20 micrograms/ml, a minimum quantifiable level of 25 ng/ml, absolute recovery of greater than 90% (n = 15), and precision of less than or equal to 8.8% (n = 45). The method was used in a preliminary dose proportionality study in the dog.

Animals↗
PubMed2002

Determination of polychlorinated biphenyls in small-size serum samples by solid-phase extraction followed by gas chromatography with micro-electron-capture detection.

An new method for the determination of polychlorinated biphenyls (PCBs) in serum samples of up to 1 ml has been developed. The procedure consisted in the solid-phase extraction (SPE) of the analytes on an Oasis cartridge and the subsequent on-line elimination of the fat by directly dropping of the eluate from the SPE cartridge on a multilayer column placed below the cartridge. This configuration allowed minimising of the sample manipulation as well as the time, solvent and sorbent consumption (i.e. complete sample preparation can be accomplished in about 1 h with only 3 ml of toluene and 300 mg of silica). The SPE plus clean-up method developed showed a satisfactory performance for the analysis of PCBs in rat serum samples providing similar recoveries (i.e. range 73-128% for most of the congeners selected) at the different spiking levels investigated (1.25, 0.50 and 0.25 ng/ml). Detection limits using a microelectron capture detector were in the range 0.01-0.30 ng/ml of serum and the relative standard deviations of the complete method better than 18% irrespective of the PCB concentration. The validated method has been applied to the evaluation for the first time of the PCB levels in serum samples of up to 1 ml from individuals of an Egyptian Vulture colony in Spain.

Animals↗
PubMed2005

On-line solid-phase extraction coupled with high-performance liquid chromatography and tandem mass spectrometry (SPE-HPLC-MS-MS) for quantification of bromazepam in human plasma: an automated method for bioequivalence studies.

A validated method for on-line solid-phase extraction coupled with high-performance liquid chromatography tandem mass spectrometry (SPE-HPLC-MS-MS) is described for the quantification of bromazepam in human plasma. The method involves a dilution of 300 muL of plasma with 100 muL of carbamazepine (2.5 ng/mL), used as internal standard, vortex-mixing, centrifugation, and injection of 100 muL of the supernate. The analytes were ionized using positive electrospray mass spectrometry then detected by multiple reaction monitoring (MRM). The m/z transitions 316-->182 (bromazepam) and 237-->194 (carbamazepine) were used for quantification. The calibration curve was linear from 1 ng/mL (limit of quantification) to 200 ng/mL. The retention times of bromazepam and carbamazepine were 2.6 and 3.2 minutes, respectively. The intraday and interday precisions were 3.43%-15.45% and 5.2%-17%, respectively. The intraday and interday accuracy was 94.00%-103.94%. This new automated method has been successfully applied in a bioequivalence study of 2 tablet formulations of 6 mg bromazepam: Lexotan(R) from Produtos Roche Químicos e Farmacêuticos SA, Rio de Janeiro, Brazil (reference) and test formulation from Laboratórios Biosintética Ltda, São Paulo, Brazil. Because the 90% CI of geometric mean ratios between reference and test were completely included in the 80%-125% interval, the 2 formulations were considered bioequivalent. The comparison of different experimental conditions for establishing a dissolution profile in vitro along with our bioavailability data further allowed us to propose rationally based experimental conditions for a dissolution test of bromazepam tablets, actually lacking a pharmacopeial monograph.

Adult↗
PubMedDate not supplied

Simultaneous determination of imazalil and its major metabolite in citrus fruit by solid-phase extraction and capillary gas chromatography with electron capture detection.

A method was developed for the simultaneous determination of imazalil and its major metabolite, R 14821, in citrus fruit. This method (designated the SPE method) is based on solid-phase extraction (SPE) and capillary gas chromatography (GC) with electron-capture detection (ECD). The SPE method is highly sensitive for both compounds (limit of detection for each: 0.001 microg/g) and is less time consuming than the previously reported method based on repeated liquid-liquid partitioning and GC-ECD. Recoveries for 3 levels of fortification (0.02, 0.2, and 2.5 microg/g) from satsuma mandarins ranged from 94.3 to 96.5% for imazalil and from 93.9 to 96.3 % for R 14821, with coefficients of variation (CVs) ranging from 3.1 to 6.3% for imazalil and from 4.5 to 5.6% for R 14821. Average residual levels found in grapefruit, oranges, and lemons by the SPE method and the previously reported method, and the corresponding CVs, were similar.

Chromatography, Gas↗
PubMedDate not supplied

Rapid determination of methyl parathion and methyl paraoxon in milk by gas chromatography with solid-phase extraction and flame photometric detection.

Methyl parathion (MPT; O,O-dimethyl-O-4-nitrophenyl phosphorothioate) and its active metabolite, methyl paraoxon (MPO; O,O-dimethyl-O-4-nitrophenyl phosphate), were isolated from raw milk by solid-phase extraction (SPE) and determined by gas chromatography with flame photometric detection. The SPE method was compared with a traditional liquid-liquid extraction (LLE) procedure to determine whether SPE had suitable sensitivity and better efficiency in extracting MPT and MPO from milk of cows and goats. Method detection limits were higher for SPE, but the differences were not significant (t-test). Recoveries of MPT and MPO from raw milk samples spiked at 0.05, 0.5, and 5.0 micrograms/mL ranged from 80.0 to 118%, and the coefficients of variation were usually less than 10% for both methods. LLE required more organic solvents and was more time consuming compared with SPE.

Animals↗
PubMed1996

Solid-phase extraction and HPLC analysis of kebuzone and its metabolites in blood.

A HPLC method for quantification of kebuzone and its metabolites in whole blood was developed. The compounds and the internal standard were isolated from blood by solid-phase extraction on a C-18 cartridge. A blood sample was to be hemolyzed before extraction. HPLC was performed on a C-18 column with the mobile phase composed of methanol/water acidified to pH 2.7 and UV absorbance detection at 247 nm. This method has been successfully applied to a pharmacokinetic study of kebuzone and its metabolites in rabbits.

Animals↗
PubMed2005

Development and validation of a microsomal online cytochrome P450 bioreactor coupled to solid-phase extraction and reversed-phase liquid chromatography.

The development and validation of an online cytochrome P450 (CYP)-based bioreactor coupled to automated solid-phase extraction (SPE) and gradient HPLC separation is described. The analytical method was checked on intra- and inter-day repeatability of the ethoxyresorufin-O-demethylation (EROD) reaction with CYP 1Al/1A2 containing beta-NF induced rat liver microsomes as an enzyme source. These experiments showed that CYP activity was linearly decreased with 16% over an 11 h period. Inter-day measurements had a CV of 9.1%. Furthermore, Km and Vmax values of the EROD reaction, measured with the bioreactor, were 2.72 +/- 0.46 microM and 7.9 +/- 0.5 nmol/min/mg protein, respectively. These were in good correspondence with Km and Vmax values, measured with standard batch assay, which amounted 0.66 +/- 0.08 microM and 6.4 +/- 0.2 nmol/min/mg protein respectively. In conclusion the newly developed analytical method can be used effectively and at a microliter scale for online generation, extraction and separation of metabolites.

Animals↗
PubMed1986

Solid-phase extraction and reversed-phase high-performance liquid chromatographic technique for isolation and estimation of platelet activating factor in plasma.

A solid-phase extraction technique for the isolation of platelet activating factor [1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (AGEPC)] from biological matrices was developed. Amberlite XAD-2 was effective in retaining different molecular species of AGEPC from plasma and incubation media. The recovery of the three molecular species (C14-, C16-, and C18-AGEPC) was greater than 95%. XAD-2 also removed large amounts of plasma impurities, giving a cleaner high-performance liquid chromatographic (HPLC) profile. AGEPC in plasma or incubation media was not significantly removed by passage of the sample through a column packed with ODS-silica. A reversed-phase HPLC technique for separation and estimation of different species of AGEPC was developed. Resolution of C14-, C16- and C18-AGEPC was accomplished on a Hamilton PRP-1 resin column using an aqueous acetonitrile gradient containing 1 mM methanesulphonic acid. The detection limit was of the order of 50 ng of AGEPC at 210 nm. The AGEPC purified by the technique described retained its biological activity as determined by its ability to release endogenous serotonin from rabbit platelets.

Chromatography, High Pressure Liquid↗
PubMed2004

Preconcentration and determination of priority pollutant phenols in waters at trace levels using a polymeric solid-phase extraction cartridge.

A method to preconcentrate and analyse the EPA priority pollutant phenols from water samples is evaluated. Spe-ed Advanta cartridges, containing 100mg of a polymeric matrix modified with polar groups, are used in the extraction and enrichment step. Several parameters are studied in order to find the best experimental conditions to perform a solid-phase extraction process. Sample flow rate and pH appear as variables that could significantly affect the recoveries obtained. Water samples need a pH adjustment to values lower than 3 units and must be percolated through the cartridges with flow rates over 5 mL min(-1). The highest recoveries and preconcentrations are obtained using acetonitrile as the elution solvent. Sample volumes from 100 mL to 1 L with concentrations ranging from 50 to 0.5 microg L(-1) are analysed with quantitative recoveries and similar efficiencies being achieved. After establishing the best conditions, we applied the method to the analysis of spiked natural waters.

Acridines↗
PubMed2000

Part-per-trillion level determination of antifouling pesticides and their byproducts in seawater samples by off-line solid-phase extraction followed by high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

A new method for the simultaneous determination of antifouling pesticides and some of their byproducts such as dichlofluanid, diuron and its byproducts [demethyldiuron and 1-(3,4-dichlorophenyl)urea], (2-thiocyanomethylthio)ben: zothiazole, chlorothalonil, Sea-nine 211, Irgarol 1051 and one of its byproducts (2-methylthio-4-tert.-butylamino-s-triazine) in seawater was developed. The extraction of these compounds from the filtered seawater samples was performed off-line with different solid-phase extraction sorbents using (I) a 500 mg graphitized carbon black cartridge (ENVI-Carb) and (II) 200 mg polymeric cartridges (LiChrolut EN and Isolute ENV+) and passing 500 ml of the sample through these cartridges. The detection was carried out by reversed-phase high-performance liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry both in the negative and positive ion modes. The recovery ranged from 76 to 96% for the whole antifouling group with the ENVI-Carb cartridges and the detection limit was at the part-per-trillion level except for TCMTB. The method utilizing the polymeric cartridge proved to be very useful, time saving and with good recoveries when only Irgarol and its byproduct, Sea-nine 211 and diuron and its byproducts, have to be analyzed. The different cartridges were applied to the analysis of these pesticides in different marinas of the Catalan coast; diuron, dichlofluanid, Sea-nine 211, Irgarol as well as demethyldiuron and the Irgarol byproduct being the must ubiquitous pollutants. Maximum concentration levels were 2-3.5 microg/l of diuron and Sea-nine 211, respectively.

Atmospheric Pressure↗
PubMed1991

Quantitative high-performance liquid chromatographic, gas chromatographic, and gas chromatographic-mass spectrometric analysis of ticlopidine in baboon plasma after solid-phase extraction.

High-performance liquid chromatography with UV detection (HPLC-UV) and gas chromatography with either nitrogen phosphorus (GC-NPD) or mass spectrometry (GC-MS) detection were used for the determination of ticlopidine in plasma. Solid-phase extraction of ticlopidine from plasma was performed using Extrelut columns without pH adjustment, and using hexane as the solvent of elution. With HPLC, a mobile phase of 0.01 M pH 7.8 phosphate buffer:acetonitrile (70:30) was passed through a mu Bondapack C-18 column at a rate of 1.3 mL/min. Ultraviolet detection at 235 nm was sensitive to plasma ticlopidine concentrations of 0.05 micrograms/mL. The GC-NPD and GC-MS were performed on a DB-17 fused-silica column using on-column injection. For GC-NPD and GC-MS, limits of quantification were found to be 0.020 and 0.005 micrograms/mL, respectively. Compared with HPLC-UV, the GC methods were found to be more reproducible, sensitive, and specific and therefore more suitable for pharmacokinetic applications.

Animals↗
PubMed1991

Sensitive determination of buspirone in serum by solid-phase extraction and two-dimensional high-performance liquid chromatography.

A selective and sensitive determination of buspirone in serum by high-performance liquid chromatography is described. The procedure is based on separation on a C18 column. A solid-phase extraction procedure is used for sample clean-up. The retention on the first column is based on the hydrophobic interaction of buspirone with the stationary phase, and the retention on the second column is based on ionic interactions due to the presence of sodium lauryl sulphate in the mobile phase as well as hydrophobic interaction. This allows for good separation of buspirone from impurities and consequently allows lower detection limits than previously reported for liquid chromatographic methods. Detection by ultraviolet absorbance gives a detection limit of 0.2 ng/ml.

Buspirone↗
PubMed1995

Amphetamine and methamphetamine determination in urine by reversed-phase high-performance liquid chromatography with sodium 1,2-naphthoquinone 4-sulfonate as derivatizing agent and solid-phase extraction for sample clean-up.

A rapid method is described for the identification and determination of amphetamine and methamphetamine in human urine samples by liquid chromatography with UV-Vis detection. The samples were transferred onto a C18 solid-phase extraction column and chromatographed on a Hypersil ODS RP C18, 5 microns (250 x 4 mm I.D.) with an acetonitrile-water elution gradient containing propylamine. Under these conditions, the amines are eluted with a short retention time. The procedure has been applied to the determination of amphetamine and methamphetamine in the range 0.3-4.0 micrograms/ml in spiked urine samples. The detection limits at 280 nm were 4 and 2 ng/ml for amphetamine and methamphetamine, respectively. The intra-day and inter-day precision and accuracy of the method were studied.

Amphetamine↗
PubMed1996

Analysis of L-[methyl-11C]methionine and metabolites in human plasma by an automated solid-phase extraction and a high-performance liquid chromatographic procedure.

A fully automated method for separation of L-[methyl-11C]Methionine from metabolites in patient plasma was developed. L-[methyl-11C]Methionine was isolated from plasma by solid-phase extraction (SPE). The radioactivity retained on the SPE column was eluted and injected onto the HPLC system for separation of in vivo formed L-[methyl-11C]methionine radiolabeled metabolites. The yield through the isolation procedure and HPLC analysis was greater than 95% with a precision better than 5% (R.S.D.). The calculated rate of L-[methyl-11C]methionine transport into tumor tissue was markedly different with and without compensation for radiolabeled metabolites in patient plasma.

Chromatography, High Pressure Liquid↗