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PubMed1997

Determination of tramadol in human plasma by capillary gas chromatography-mass spectrometry using solid-phase extraction.

An analytical method using solid-phase extraction, capillary gas chromatography and mass selective detection in the electron-impact ionization (EI) mode was developed for the determination of tramadol (2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol) in human plasma. The advantages of this method are the high sensitivity and selectivity and the linearity over the concentration range 2-500 ng/ml. Quantification was made using nefopam as an internal standard, and the detection limit was found to be 1 ng/ml. The standard deviations of the intra-day precision test ranged from 4.5 to 6.0% with respect to the concentration. Accuracy ranged from 1.0 to 4.0% (inter-day). The method was used for the determination of tramadol in a bioequivalence study.

Analgesics, Opioid↗
PubMed2002

Determination of iron, manganese and zinc in water samples by flame atomic absorption spectrophotometry after preconcentration with solid-phase extraction onto Ambersorb 572.

A solid-phase extraction method for the preconcentration of Fe, Mn and Zn on a column containing Ambersorb 572 has been developed, and the determination of Fe, Mn and Zn in water using a flame atomic absorption spectrophotometer (FAAS) has been performed. The optimum preconcentration parameters of the procedure have been determined. The effect of the pH, complexing agent, amount of adsorbent, flow rate, concentration and volume of the elution solution and interfering ions on the recovery of the analytes were investigated. The recoveries of Fe, Mn and Zn were 99 +/- 3%, 98 +/- 3% and 99 +/- 3% at the 95% confidence level, respectively, under the optimum conditions. Fe, Mn and Zn were preconcentrated up to 50, 100, 200, respectively. The limits of detection of Fe, Mn and Zn are 2.5, 0.68 and 0.24 micrograms l-1, respectively. The adsorption capacity of the adsorbent was found to be 10.9, 13.1 and 21.5 mg g-1 for Fe, Mn and Zn, respectively. The method has been applied to the determination of these metal ions in tap-water and river-water samples. The precision and the accuracy of the method is very good. The relative standard deviation and the relative error are lower than 4%.

Fresh Water↗
PubMedDate not supplied

Determination of organochlorine pesticide and polychlorinated biphenyl residues in fatty fish by tandem solid-phase extraction cleanup.

A rapid, multiresidue solid-phase extraction (SPE) technique for determination of organochlorine pesticide and polychlorinated biphenyl (PCB) residues in nonfatty fish was modified for use with fatty fish. In the modified procedures, samples are extracted with acetonitrile, and the extract is cleaned up with both C18 and Florisil SPE columns. Residues are determined by gas chromatography with electron capture detection. The original method was modified for use with fatty fish by reducing the amount of tissue extracted and by using an improved Florisil SPE cleanup. Recovery data are presented for 24 fortified organochlorine pesticide residues (0.12 ppm) and 3 fortified PCB residues (0.80 ppm) from flounder, bluefish, and shad samples, which contained 0.8, 5.4, and 22.6% fat, respectively. For the 3 types of fish, recoveries of 23 of 24 fortified organochlorine pesticide residues ranged from 55 to 129%, and recoveries of 3 fortified PCB residues ranged from 55 to 104%. There were no significant differences in recovery based on fish species and/or fat content for the majority of residues studied. This SPE method and the official AOAC method yielded comparable results for fish containing incurred organochlorine residues.

Animals↗
PubMed1997

Studies on the pharmacological properties of novel arylene bis(methylketone) compounds using solid-phase extraction and high-performance liquid chromatography.

A method utilising solid-phase extraction followed by high-performance liquid chromatography has been developed to quantify novel arylene bis(methylketone) chemotherapeutics present in biological samples. The samples are extracted over cyanopropylsilane solid-phase extraction cartridges using 10 mM heptanesulfonate-10 mM tetramethylammonium chloride-4.2 mM H3PO4-95% CH3CN as the eluent. Analytical chromatography utilises a diisopropyl-C8 reversed-phase column and a 7.5-45% CH3CN gradient in 10 mM heptanesulfonate-10 mM tetramethylammonium chloride-4.2 mM H3PO4-H2O. Detection was by ultraviolet spectrophotometry at 300 or 240 nm. The linear response of the assay was found to extend from at least 100 microg/ml down to 97.66 ng/ml for a 100 microl injection. The assay system was utilised to determine the plasma kinetics of the compounds in mice, where all the drugs were found to display rapid absorption and elimination following intraperitoneal dosing. In vitro and in vivo studies of metabolism demonstrated that each of the compounds produced several metabolites, and that this conversion could be extensive in vivo.

Aniline Compounds↗
PubMed2005

Determination of triptolide in root extracts of Tripterygium wilfordii by solid-phase extraction and reverse-phase high-performance liquid chromatography.

Extracts of Tripterygium wilfordii roots have a long history of use in traditional Chinese medicine and have shown great promise in recent clinical trials as a treatment for rheumatoid arthritis. The major active component of Tripterygium root extracts is the diterpenoid triptolide. This paper describes a method for the determination of triptolide in root extracts that is suitable for the analysis of many small samples simultaneously. Extracts are applied to aminopropyl solid-phase extraction (SPE) tubes that are then eluted with dichloromethane-methanol (49:1, v/v). The eluate is chromatographed on a pentafluorophenyl HPLC column using an acetonitrile:water gradient. Triptolide is quantified by ultraviolet detection at 219 nm. Using this method, it was shown that smaller diameter roots with secondary growth contained higher triptolide concentrations than larger roots. This suggests that roots to be used for production of the drug extract could be harvested while still small, which would reduce the growing time necessary and thus be economically beneficial for the growers.

Celastraceae↗
PubMed1997

Molecularly imprinted solid phase extraction of atrazine from beef liver extracts.

Molecularly imprinted polymers were used as specific binding matrices for the solid phase extraction and cleanup of biological sample extracts. To demonstrate this, an anti-atrazine polymer was used to cleanup organic extracts of beef liver. Atrazine retention on the columns was greatest in chloroform. The binding capacity of the polymer in chloroform was 19 mumol of atrazine per gram. Purified and unpurified beef liver extracts were analyzed by both reversed-phase HPLC and ELISA. The use of molecularly imprinted solid phase extraction (MISPE) improved the accuracy and precision of the HPLC method and lowered the limit of detection (0.005 ppm). Atrazine recovery as determined by HPLC from beef liver homogenates spiked to levels from 0.005 to 0.5 ppm averaged 88.7% following MISPE and 60.9% for the unpurified extracts. Atrazine recovery as determined by ELISA averaged 92.8% following MISPE and 79.6% for the unpurified extracts. Crude tissue sample extracts interfered with both the HPLC and ELISA methods. However, the use of MISPE allowed for the rapid analysis of complex biological matrices using either method at the tolerance level of 0.02 ppm in meat products. The application of molecular imprinting technology for solid phase extraction is a new approach for the analysis of highly lipophilic low molecular weight contaminants.

Animals↗
PubMed2002

On-line coupling of miniaturized solid-phase extraction and microcolumn liquid-phase separations.

On-line coupling of miniaturized solid-phase extraction methods and microcolumn separation techniques are reviewed. A conventional solid-phase micro-extraction device and fiber-in-tube solid-phase extraction was employed as the sample preparation method. In the fiber-in-tube technique, a novel fibrous polymeric material was introduced as the extraction medium for the microscale sample preparation step which could be directly coupled with microcolumn liquid-phase separation systems, such as microcolumn liquid chromatography, capillary electrophoresis, and capillary electrochromatography. The applications of these hyphenated systems, consisting of the sample preparation and separation processes, are also reviewed.

Capillary Action↗
PubMed1992

Determination of cocaine and benzoylecgonine in human amniotic fluid using high flow solid-phase extraction columns and HPLC.

A new solid-phase extraction procedure for the determination of cocaine and benzoylecgonine in amniotic fluid, using high flow co-polymeric sorbents is reported. The recoveries of cocaine and benzoylecgonine within the range 0.1-1 mg/l were 95.7% and 50.3%, respectively. The use of high-flow sorbents allowed the easy extraction of amniotic fluid regardless of sample viscosity or physical nature. The use of these solid-phase columns provided many advantages over the more commonly used solvent extraction, including an increase in extraction speed and efficiency, reduced operator time, reduced solvent use and disposal volumes and exceptional extract quality. Further, the determination of amniotic fluid obtained from pregnant cocaine users may provide important information about handling of cocaine by the fetus at various gestational ages. The procedure was successfully applied to amniotic fluid from suspected cocaine abusers.

Amniotic Fluid↗
PubMed2002

Dynamic microwave-assisted extraction coupled on-line with solid-phase extraction: determination of polycyclic aromatic hydrocarbons in sediment and soil.

This paper describes a new extraction tool for the determination of polycyclic aromatic hydrocarbons (PAHs) in soil and sediment samples, using dynamic microwave-assisted extraction combined with solid-phase extraction (DMAE-SPE). The critical variables for DMAE-SPE are investigated and optimized in an experimental design. The technique proved to be fast, accurate and able to yield quantitative extraction of PAHs from naturally contaminated sediment and soil samples. The set-up is fully automated and features monitored extraction, which facilitates rapid optimization of the method. In addition, only small quantities of solvent and sample are required.

Chromatography, Gas↗
PubMed2002

Improved tert-butyldimethylsilylation gas chromatographic/mass spectrometric detection of nerve gas hydrolysis products from soils by pretreatment of aqueous alkaline extraction and strong anion-exchange solid-phase extraction.

In the analysis of tert-butyldimethylsilyl derivatives (IBDMS) of alkyl methylphosphonic acids (RMPA) and methylphosphonic acid (MPA), from soils by gas chromatography/mass spectrometry (GC/MS), the detection yields are generally low, due to the suppression of TBDMS derivatization by the soil matrix components and the adsorption of RMPA and MPA to the soils. An ion-exchange pretreatment of the aqueous soil extract can be used to overcome the former factor by removing interfering compounds. A pretreatment method is described for improving the detection yields due to the latter factor, using an alkaline extraction procedure. The recovery was estimated quantitatively using capillary electrophoresis. The soil samples tested included volcanogenous immature soils and showed a low aqueous extraction recovery and GC/MS detection yields. The inclusion of sodium hydroxide in the extraction solvent dramatically increased the recovery. Using a 0.1 M sodium hydroxide solution, the recovery was in excess of 68%. Interfering components were removed from the alkaline soil extract by solid-phase extraction of the acids on a silica-based strong anion exchanger. The alkaline soil extract was neutralized with hydrofluoric acid and applied to the cartridge in the fluoride form. After washing with water, MPA and RMPA could be eluted with methanolic ammonia nearly quantitatively. Using the established pretreatment method, MPA and RMPA were detected from all the soil samples in more than 67% yield.

Journal Article↗
PubMed2000

Efficient sample pre-concentration of bupivacaine from human plasma by solid-phase extraction on molecularly imprinted polymers.

The ability to use imprinted polymers for solid-phase extraction is demonstrated in a model pre-concentration of bupivacaine from human plasma samples prior to gas chromatography. Imprinting of the structural analogue pentycaine yielded a sorbent which efficiently extracted analyte and internal standard, while possible interference on analyte quantification from leakage of remaining template molecules was eliminated. Human plasma samples were diluted with citrate buffer pH 5, and applied onto solid phase extraction columns containing 15 mg of imprinted sorbent. Wash steps with 20% methanol in water followed by acetonitrile preceded elution with 2% triethylamine in acetonitrile. A direct comparison with conventional sample pre-treatment methods showed the high selectivity of the imprinted sorbent resulted in distinctly cleaner chromatographic traces than were obtained both after liquid-liquid extraction and C18-based solid-phase extraction.

Anesthetics, Local↗
PubMed1998

Comparison of the properties of polymeric and C8 based materials for solid phase extraction.

The extraction properties of two polymeric solid phase extraction materials, styryldivinyl benzene (SDB) and 'Oasis' have been compared with those of a base deactivated C8 bonded silica gel using a range of acidic and basic test analytes. In the case of the two polymer phases good extraction of all the test compounds from aqueous buffer was obtained over the pH range 2-10. On the C8 material, efficient extraction of the most polar acidic analyte, anisic acid, was only obtained between pH 2 and 6. The use of methanol water mixtures, or methanol water mixtures modified with either trifluoroacetic acid (TFA) or triethylamine (TEA) as eluents was investigated for the recovery of the analytes following extraction. The use of TFA or TEA as ionic modifiers strongly influenced the efficiency of the elution step. The effect of a plasma matrix on extraction efficiency was also investigated, with the result depending upon the analyte. An approach to assessing the performance of the three phases has been developed based on the percentages of methanol in the eluent resulting in the recovery of 50% of the analyte, and in determining the difference between eluents giving recoveries of 10 and 90%.

Chemistry Techniques, Analytical↗
PubMed1996

Design and evaluation of an automated solid-phase extraction method development system for use with biological fluids.

An automated solid-phase extraction method development system, utilizing a Zymate XP robot and a custom-designed solid-phase extraction manifold, has been developed and validated. This system spikes blank liquid matrix, such as plasma, with solutions containing drug, internal standard, and up to three metabolites. Samples are then buffered or diluted with an appropriate reagent. After these samples and corresponding blanks have been prepared, solid-phase cartridges containing selected sorbents are automatically conditioned. Samples are robotically vortexed and transferred to the conditioned cartridges, and analytes are extracted. Validation of this robotic system demonstrated acceptable precision and accuracy for three types of liquid transfer, including metering pump ( < 6% RSD and RE for > or = 2.0 mL dispensation), syringe-based laboratory station ( < or = 2.9% RSD and 0.5% RE for volumes between 0.25 and 1.00 mL), and syringe hands ( < 3.5% RSD and RE for volumes between 0.10 and 1.00 mL). For two example compounds, the system provided data which effectively distinguished good solid-phase sorbents from marginal ones through precision, recovery, and chromatographic selectivity. Solid-phase extraction of these compounds from human plasma gave precision (2-10% RSD) and extraction efficiency (96 +/- 6%) comparable to results obtained from manual extractions (92 +/- 11%).

Body Fluids↗
PubMed2004

Simple strategy for the optimization of solid-phase extraction procedures through the use of solid-liquid distribution coefficients application to the determination of aliphatic lactones in wine.

A practical strategy for the optimization of solid-phase extraction (SPE) systems is presented. Critical SPE volumes (sample loaded, rinsing and elution solvent) are calculated from solid-liquid extraction coefficients and from basic bed parameters determined in simple experiments, using the Lövkist Jonsson model and other expressions derived from the general theory of chromatography. The agreement between calculated and measured volumes is satisfactory, which makes it possible to consider different sorbents and rinsing and elution solvents in the SPE optimization with a relatively low experimental effort. The strategy has been successfully applied to the optimization of a SPE method directed to the selective extraction of aliphatic lactones from wine. Six different reversed-phase sorbents were studied and the one showing maximum extraction selectivity was selected. Wine (50 ml) is extracted in a 200 mg cartridge filled with Bond Elut-ENV resins. Interferences are removed with 20 ml of methanol-water (40:60) with 1% NaHCO3. Elution is carried out with 1.8 ml of dichloromethane. The extract is concentrated to 0.15 ml and analyzed by GC-ion trap MS. Eight odor-active aliphatic gamma and delta lactones (with 8-12 C atoms) from wine are recovered (R > 75%) in an extract free from wine major volatiles. Detection limits are in the 40-300 ng/l range, well below the odor detection threshold of these compounds. Linearity (r2 > 0.996) and precision (average R.S.D. 3.5%) are satisfactory in all cases. The levels in wine of some of these lactones (gamma-octa, undeca and dodecalactones) are reported by first time and results demonstrate that can be present at concentrations above or close to their corresponding odor thresholds.

Chromatography, Liquid↗
PubMed1999

Comparison of plasma sample purification by manual liquid-liquid extraction, automated 96-well liquid-liquid extraction and automated 96-well solid-phase extraction for analysis by high-performance liquid chromatography with tandem mass spectrometry.

Three extraction procedures were developed for the quantitative determination of a carboxylic acid containing analyte (I) in human plasma by high-performance liquid chromatography (HPLC) with negative ion electrospray tandem mass spectrometry (MS-MS). The first procedure was based on the manual liquid-liquid extraction (LLE) of the acidified plasma samples with methyl tert.-butyl ether. The second procedure was based on the automation of the manual LLE procedure using 96-well collection plates and a robotic liquid handling system. The third approach was based on automated solid-phase extraction (SPE) using 96-well SPE plates and a robotic liquid handling system. A lower limit of quantitation of 50 pg/ml was achieved using all three extraction procedures. The total time required to prepare calibration curve standards, aliquot the standards and plasma samples, and process a total of 96 standards and samples by manual LLE was three-times longer than the time required for 96-well SPE or 96-well LLE (4 h, 50 min vs. 1 h, 43 min). Even more importantly, the time the bioanalyst physically spent on the 96-well LLE or 96-well SPE procedure was only a small fraction of the time spent on the manual LLE procedure (<10 min vs. 4 h, 10 min). It should be noted that the 96-well SPE procedure incorporated the two steps of evaporation of the eluates to dryness and subsequent reconstitution of the dried extract. The total time required for the 96-well SPE could be reduced by 50% if the eluates were injected directly, eliminating the drying and reconstitution steps, which is achievable when sensitivity is less of an issue.

Automation↗
PubMed2005

A new molecularly imprinted polymer for selective extraction of cotinine from urine samples by solid-phase extraction.

Cotinine, the main metabolite of nicotine in human body, is widely used as a biomarker for assessment of direct or passive exposure to tobacco smoke. A method for molecularly imprinted solid-phase extraction (MISPE) of cotinine from human urine has been investigated. The molecularly imprinted polymer (MIP) with good selectivity and affinity for cotinine was synthesized using cotinine as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The imprinted polymer was evaluated for use as a SPE sorbent, in tests with aqueous standards, by comparing recovery data obtained using the imprinted form of the polymer and a non-imprinted form (NIP). Extraction from the aqueous solutions resulted in more than 80% recovery. A range of linearity for cotinine between 0.05 and 5 microg mL-1 was obtained by loading 1 mL blank urine samples spiked with cotinine at different concentrations in acetate buffer of pH 9.0, and by using double basic washing and acidic elution. The intra-day coefficient of variation (CV) was below 7% and inter-day CV was below 10%. This investigation has provided a reliable MISPE-HPLC method for determination of cotinine in human urine from both active smokers and passive smokers.

Chromatography, High Pressure Liquid↗
PubMed2002

Enantioselective analysis of atenolol in biologic fluids: comparison of liquid-liquid and solid-phase extraction methods.

In this study we evaluated a liquid-liquid extraction procedure and a solid-phase extraction procedure for sample preparation for the enantioselective analysis of atenolol in plasma and urine by high-performance liquid chromatography. A Chiralcel OD-H column was used for the resolution of atenolol enantiomers with hexane-ethanol (85:15, v/v) plus 0.1% diethylamine as the mobile phase. In the liquid-liquid extraction procedure, atenolol was extracted from alkalinized body fluids with 5 ml chloroform-2-propanol (4:1, v/v). In the solid-phase extraction procedure, atenolol was isolated from plasma using a C8 column and methanol. Both extraction procedures were efficient in recovering atenolol and removing endogenous interferents. The RSDs and deviation from nominal values were lower than 10% for both within-day and between-day assays. The results show that there were no statistically significant differences in between-day variation. The t-test showed that there were no significant differences between the real concentrations and the determined concentrations. The limit of quantitation was 10 ng/ml and the linear range was 10-5,000 ng/ml for both methods. These methods can be used in pharmacokinetic studies.

Adrenergic beta-Antagonists↗
PubMed2003

Dynamic microwave-assisted extraction coupled on-line with solid-phase extraction and large-volume injection gas chromatography: determination of organophosphate esters in air samples.

An on-line method was developed for the extraction, cleanup, and analysis of airborne organophosphate esters collected on glass fiber filters. The extraction and cleanup step was performed by conducting the dynamic microwave-assisted extraction (DMAE) coupled to solid-phase extraction (SPE). This system was further connected to include large-volume injection gas chromatography. The Injection interface was a programmable temperature vaporizer. The system performance test was investigated using spiked glass fiber filters. The DMAE-SPE recovery of the organophosphate esters was found to be greater than 97%. The repeatability of the uncorrected peak areas and the retention times was determined to be 4.2-8.0 and 0.03% relative standard deviation, respectively, and limits of detection were in the range 61-186.2 pg/m3. The method was tested in a newly restored office, in which several of the targeted organophosphate esters were detected. The total sampling and analysis time was less than 1.5 h.

Air Pollutants↗