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PubMed2006

[Determination of methamphetamine in whole blood by capillary zone electrophoresis after solid phase extraction].

OBJECTIVE: To develop a specific CZE method for the determination of methamphetamine in whole blood after solid phase extraction. METHODS: With the doxapram as internal standard, Oasis column was used to extract drugs from whole blood and the sample was analysized by CZE. RESULTS: The method showed excellent linearity and the linear correlation coefficient was 0.994. The relative standard deviation for between-day and within-day were 5.31% and 2.22%, respectively. CONCLUSION: The method is effective, simple, reliable and has been used in the determination of methamphetamine in whole blood.

Doxapram↗
PubMed2004

Determination of 21 organochlorine pesticides in tree leaves using solid-phase extraction clean-up cartridges.

A method to determine 21 organochlorine pesticides (OCPs) in tree leaves [chestnut (Castanea sativa), hazel (Corylus avellana), oak (Quercus robur) and walnut tree (Juglans regia)] based on microwave-assisted extraction (MAE) followed by solid-phase extraction (SPE) clean-up is described. After extraction with hexane:acetone (50:50), four different sorbents (Florisil, tandem Florisil + alumina, silica and ENVI-Carb) were assayed for the clean-up step. Pesticides were eluted with 5 mL of hexane:ethyl acetate (80:20) and determined by gas chromatography and electron capture detection (GC-ECD). Carbon was the sorbent, which provided colourless eluates and chromatograms with less interferent compounds. Analytical recoveries obtained were ca. 100% for all the studied pesticides with this sorbent.

Chromatography, Gas↗
PubMed1999

Development and validation of a sensitive solid-phase extraction and high-performance liquid chromatographic assay for the novel bio-reductive anti-tumor agent RH1 in human and mouse plasma.

A HPLC assay and solid-phase extraction technique from human plasma has been developed and validated for the experimental anticancer agent, RH1 (2,5-diaziridinyl-3-hydroxymethyl-6-methyl-1,4-benzoquinone) which is currently being evaluated by the CRC phase I/II committee. A 500 mg amino propyl solid-phase extraction cartridge was used to isolate RH1 from human plasma. Analysis was performed on a reversed-phase chromatography system using a 15 cm cyanopropyl column and isocratic elution with a 10% methanol-90% water (double distilled) solution. The lower limit of quantitation for RH1 was found to be 0.00375 microg/ml (3.75 ng/ml+/-8.3%) in water and following extraction from plasma. Recovery of >80%(+/-11.9%) was achieved over a five-day validation study. This method was used to carry out pre-clinical studies in BDF mice (standard strain of hybrid mice) at three dose levels (2, 5 and 10 mg/kg of RH1 in 0.9% (w/v) saline via an intraperotoneal injection). Standard Version of PC Winnonlin pharmacokinetic modelling software was used to model the data. A none-compartmental model was used to describe the disposition of RH1 in mice plasma. RH1 was rapidly eliminated from plasma with a mean plasma clearance of 23.4 ml/min, mean volume of distribution of 321.6 ml and mean t(1/2) alpha and beta decays of 4.8 and 9.6 min, respectively. RH1 in human and mouse whole blood and plasma was found to be stable up to 2 h.

Animals↗
PubMed1995

Novel solid-phase extraction strategy for the isolation of basic drugs from whole blood. Preliminary study using commercially available extraction cartridges.

A novel strategy for the solid-phase extraction of basic drugs has been developed using commercial extraction cartridges. The procedure involves the sequential application of very different isolation mechanisms, viz. hydrophobic extraction on non-porous carbon followed by ionic extraction on a strong cation exchanger. This approach to extraction achieves both high recoveries and clean extracts when analysed by GC-MS. The potential for automation has been demonstrated using commercial sample preparation equipment.

Adsorption↗
PubMed2004

Rapid determination of benzo(a)pyrene in olive oil samples with solid-phase extraction and low-pressure, wide-bore gas chromatography-mass spectrometry and fast liquid chromatography with fluorescence detection.

Benzo(a)pyrene (B(a)P) was extracted from olive oil using solid-phase extraction on columns filled with Florisil and Nucleoprep C18. The extracts were analyzed with GC-MS, using standard capillary column and low-pressure wide-bore column (LP-GC-MS), as well as with HPLC on standard column and short donor-acceptor complex chromatography (DACC) column. Quantitation was done with isotope dilution method (GC-MS and LP-GC-MS) or with internal standard benzo(k)fluoranthene (HPLC). Limits of detection were 1 ng/g for GC-MS on standard column, 1.6 ng/g on LP-column, 0.5 ng/g for HPLC on standard column, and 0.3 ng/g on DACC column, respectively. The applied extraction method allowed handling over 50 samples per day and assured recovery over 80%. Matrix solid-phase dispersion, tried as an alternative isolation method, appeared less advantageous. Fast chromatographic methods (LP-GC-MS and HPLC on DACC) made it possible to reduce analysis time to 8 and 5 min, respectively. The method was applied to routine analysis of B(a)P in olive oil samples.

Benzo(a)pyrene↗
PubMed2003

Determination of copper, nickel, cobalt, silver, lead, cadmium, and mercury ions in water by solid-phase extraction and the RP-HPLC with UV-Vis detection.

A new method for the simultaneous determination of seven heavy metal ions in water by solid-phase extraction and reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The copper, nickel, cobalt, silver, lead, cadmium, and mercury ions were pre-column derivatized with tetra( m-aminophenyl)porphyrin (T m-APP) to form colored chelates. The metal-T m-APP chelates in 100 mL of sample were preconcentrated to 1 mL by solid-phase extraction with a C(18 )cartridge; an enrichment factor of 100 was achieved. The chelates were separated on a Waters Xterra()RP(18) column by gradient elution with methanol (containing 0.05 mol L(-1) pyrrolidine-acetic acid buffer salt, pH 10.0) and acetone (containing 0.05 mol L(-1) pyrrolidine-acetic acid buffer salt, pH 10.0) as mobile phase at a flow rate of 1.0 mL min(-1) and detected with a photodiode array detector. The detection limits of copper, cobalt, nickel, silver, lead, cadmium, and mercury are 2, 2, 3, 4, 3, 3, and 3 ng L(-1), respectively, in the original sample. The method was also applied to the determination of these metals in water with good results.

Journal Article↗
PubMed1988

High-performance liquid chromatographic determination of doxorubicin in tissues after solid phase extraction.

A method is described for the determination of doxorubicin in tissues. The drug was selectively extracted from the biological matrix by solid phase extraction using 1-ml octadecyl silane extraction columns. Prior to extraction, tissue samples were digested by an enzymic digestion procedure. Daunorubicin was used as an internal standard. Quantitation was by high-performance liquid chromatography (HPLC) using ion-pair chromatography on a reversed-phase column. Detection was by fluorescence. Recovery of doxorubicin from tissue was 81.7 +/- 2.1% mean +/-SD. Doxorubicin concentrations as low as 0.01 mg kg(-1) could be determined. A typical value of the relative standard error of measurement was 3.7% at 2.1 mg kg(-1).

Journal Article↗
PubMed1997

Robotic solid-phase extraction of amphetamines from urine for analysis by gas chromatography-mass spectrometry.

We have evaluated the use of the Hamilton Microlab 2200 robotic pipetting system modified to conduct solid-phase extractions of amphetamines from urine. The Hamilton system is a programmable XYZ robotic sample handling instrument compatible with commercial solid-phase extraction (SPE) columns in the most commonly available sizes. During the extraction and elution steps, the system delivers programmable positive pressure with pressure controlled feedback so as to ensure consistent recovery. The system increases sample throughput while reducing technician hands-on time and improving sample-to-sample and batch-to-batch consistency. In comparison with the manual SPE method, the automated scheme provides similar analyte recovery, accuracy, and precision and a reduced potential for laboratory errors. The method's upper limits of linearity, detection, and lquantitation were, respectively, 10,000, 100, and 100 ng/mL for amphetamine and 25,000, 50, and 50 ng/mL for methamphetamine. Extraction recoveries for the compounds ranged from 88 to 101%. Carryover amounted to less than 0.02% even at 50,000 ng/mL concentrations of analyte. A typical automated run required 20 min of technician time versus 90 min for a corresponding manual SPE procedure. The automated procedure proved to be a reliable and labor-efficient addition to the laboratory.

Amphetamines↗
PubMed2001

A highly automated 96-well solid phase extraction and liquid chromatography/tandem mass spectrometry method for the determination of fentanyl in human plasma.

A high-throughput bioanalytical method based on automated sample transfer, automated solid phase extraction, and fast liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis, has been developed for the determination of the analgesic fentanyl in human plasma. Samples were transferred into 96-well plates using an automated sample handling system. Automated solid phase extraction (SPE) was carried out using a 96-channel programmable liquid-handling workstation using a mixed-mode sorbent. The extracted samples were then dried down, reconstituted and injected onto a silica column using an aqueous/organic mobile phase with tandem mass spectrometric detection. The method has been validated over the concentration range 0.05-100 ng/mL fentanyl in human plasma, based on a 0.25-mL sample size. The assay is sensitive, specific and robust. More than 2000 samples have been analyzed using this method. The automation of the sample preparation steps not only increased the analysis throughput, but also facilitated the transfer of the method between different bioanalytical laboratories of the same organization.

Analgesics↗
PubMed2000

Molecular imprinting for drug bioanalysis. A review on the application of imprinted polymers to solid-phase extraction and binding assay.

Molecularly imprinted polymers have been applied as selective sorbents in several analytical techniques, including liquid chromatography, capillary electrophoresis and capillary electrochromatography, solid-phase extraction, and 'immunoassay'. An advantage of this type of sorbent is the possibility to synthesize polymers with selectivity pre-determined for a particular analyte. This review critically discusses the use of imprinted polymers for analysis of drugs and other compounds in biological samples, with emphasis on their use as highly selective solid-phase extraction sorbents for sample pre-concentration and alternative binding entities in immunoassay type protocols.

Binding, Competitive↗
PubMed2003

Automated solid-phase extraction method for the determination of piperaquine in whole blood by rapid liquid chromatography.

A bioanalytic method for the determination of piperaquine in whole blood by solid-phase extraction and rapid liquid chromatography has been developed and validated. Whole blood was hemolyzed with deionized water, and an internal standard was added to the samples before they were loaded onto a PRS cation-exchange solid-phase extraction column. Piperaquine and internal standard were analyzed by liquid chromatography on a Chromolith Performance (100 x 4.6 mm) column with mobile phase acetonitrile:phosphate buffer, I = 0.1, pH 2.5 (8:92, vol/vol), flow rate 4 mL x min-1, and UV detection at 345 nm. The intraassay precision for whole blood was 3.2% at 3.00 microM and 12.3% at 0.100 microM. The interassay precision for whole blood was 1.8% at 3.00 microM and 5.2% at 0.100 microM. The lower limit of quantification and the limit of detection were 0.050 microM and 0.010 microM, respectively.

Chromatography, Liquid↗
PubMed2001

The use of polymeric solid phase extraction and HPLC analysis for the determination of ranitidine in routine plasma samples obtained from paediatric patients.

A sensitive HPLC method for the determination of ranitidine in small-volume (0.5 mL) paediatric plasma samples is described. Plasma samples were extracted using a simple, rapid solid phase extraction (SPE) technique developed using disposable copolymer packed SPE cartridges. Chromatographic separation was achieved by reverse-phase HPLC with isocratic elution using a microBondapak C18 column and a phosphate buffer (10 mM, pH 3.75)-acetonitrile (87:13 v/v) mobile phase with UV detection at 313 nm. The HPLC system exhibited linearity in the range 8-800 ng mL(-1). Intraday % CV and % bias values were in the range 1.28-8.09% (% bias -4.33 to -0.87) and interday % CV and % bias values were in the range 0.73-15.28% (% bias -1.80 to + 1.65). The limits of detection and quantitation obtained were 2 ng mL(-1) and 8 ng mL(-1), respectively, and ranitidine extraction recoveries from plasma ranged from 92.30 to 103.88%. In this study, the developed HPLC and SPE methodologies have been successfully applied to the determination of ranitidine concentrations in 68 paediatric plasma samples. The sampled population was drawn from patients already receiving the study drug therapeutically. Patients recruited had received ranitidine by two main routes - oral and intravenous. The plasma concentrations of ranitidine encountered in paediatric samples following oral or intravenous administration of a range of prescribed doses are presented graphically. These profiles are based on analysis of the first 68 plasma samples obtained from the first 35 patients recruited to the study receiving ranitidine by the oral or intravenous route.

Administration, Oral↗
PubMed1997

Identification of proteins by capillary electrophoresis-tandem mass spectrometry. Evaluation of an on-line solid-phase extraction device.

Capillary electrophoresis-tandem mass spectrometry has been used successfully for the analysis of complex peptide mixtures. The method is limited by a relatively high concentration limit of detection and by matrix effects. Here we describe on-line coupling of a solid-phase microextraction device to a capillary electrophoresis-tandem mass spectrometry system. The performance of the integrated instrument was evaluated for the identification of proteins by their amino acid sequence. We report that the concentration limit of detection was improved at least 1000 fold to the low attomole/microliter range and that matrix effects were minimized by extensive sample clean-up during solid-phase extraction. We demonstrate that the implementation of a solid-phase extraction device significantly enhances capillary electrophoresis-tandem mass spectrometry as a method for the identification of low abundance proteins isolated from high-resolution two-dimensional polyacrylamide gels.

Amino Acid Sequence↗
PubMed2000

Solid-phase extraction of quaternary ammonium herbicides.

This paper highlights recent advances in the solid-phase extraction (SPE) of quaternary ammonium herbicides in water, soil, plant and biological samples. After a brief introduction summarizing the properties of quaternary ammonium herbicides and the difficulties involved in measuring them, attention is paid primarily to solid supports used for isolation and concentration, pre-treatments required for the different matrices, and eluents applied for quantitative desorption of these analytes. The determination techniques used after SPE and applications of the proposed SPE methodology are also briefly discussed.

Chromatography, Liquid↗
PubMed2004

[Study on the solid phase extraction spectrophotometric determination of mercury in water with 5-(2-hydroxy-4-sulfo-5-chlorophenol-1-azo)-thiorhodanine].

Based on the color reaction of mercurywith 5-(2-hydroxy-4-sulfo-5-chlorophenol-1-azo)-thiorhodanine (HSTC) and the solid phase extraction of the colored complex with C18 cartridge, a new method for the determinations microg x L(-1) level of mercury was studied. In the presence of pH 3.6 HAc-NaAc buffer solution. HSTC reacted with mercury (II) to form a stable 2:1 complex. This complex was enriched by solid phase extraction with C18 cartridge and the retained complex from cartridge was eluted with DMF. An enrichment factor of 80 was achieved. In the measured solution, the molar absorptivity was 6.24 x 10(4) L x moL(-1) x cm(-1) at 545 nm. Beer's law was obeyed in the range of 0-1.5 microg x mL(-1). This method was applied to the determination of mercury in water. The relative standard devitions were 1.8%-2.2% and the recoveries were 93%-106%. The results are satisfactory.

Mercury↗
PubMed2001

Solid phase extraction gas chromatography/electron capture detector method for the determination of organochlorine pesticides in wildlife whole blood.

A gas chromatographic method for the analysis of 10 organochlorine pesticides in 0.5 mL of whole blood is described. Sample preparation involved an ethyl ether and hexane extraction, followed by a silica solid phase extraction cleanup. The pesticides are quantified by gas chromatography/electron capture detection. Method limits of detection ranged from 1.1 to 5.2 microg/L. The mean and standard deviation for the recovery of 10 pesticides was 97.9 +/- 5.5%. Recoveries from whole blood were comparable to recoveries from plasma. This indicates that the preparation of plasma is unnecessary for the quantification of organochlorine pesticides in blood. This approach is particularly useful as a nonlethal approach for monitoring pesticide contamination in small animals for which the volume of blood is limiting.

Animals↗
PubMed1994

Knowledge-based system for the automated solid-phase extraction of basic drugs from plasma coupled with their liquid chromatographic determination. Application to the biodetermination of beta-receptor blocking agents.

Techniques for the preparation of biological samples are often based nowadays on solid-phase extraction (SPE). The different SPE steps can be performed automatically on disposable extraction cartridges (DECs) by means of a sample processor. A knowledge-based system was developed to facilitate the development of fully automated methods for the solid-phase extraction of relatively hydrophobic basic drugs from plasma, coupled with their determination by high-performance liquid chromatography (HPLC). The DEC filled with 50 mg of cyanopropyl-bonded silica phase is first conditioned with methanol and buffer solution (pH 7.4). After sample application, the DEC sorbent is washed with the same buffer. The analytes are then desorbed with an appropriate eluent and the eluate is finally diluted with the same buffer as used in the HPLC mobile phase before injection. Under these conditions, only three variables are still to be optimized: the composition and volume of the elution solvent and the volume of buffer to be added to the eluate. On the basis of this general strategy, a decision tree providing information about suggested starting conditions and guidelines for the optimization of the three variables was developed and implemented by use of a hypermedia software. This didactic expert system was evaluated using several beta-receptor blocking agents as model compounds and the operating conditions obtained for the automated SPE of these compounds are presented. A method for the determination of propranolol in plasma using the SPE conditions deduced from the knowledge-based system was validated. The absolute recovery of propranolol is ca. 93% and the limit of detection is 1.3 ng ml-1. The mean within-day and between-day reproducibilities are 2.3 and 3.6%, respectively.

Adrenergic beta-Antagonists↗
PubMed1998

Improved enantioselective method for the determination of the enantiomers of reboxetine in plasma by solid-phase extraction, chiral derivatization, and column-switching high-performance liquid chromatography with fluorescence detection.

A rapid enantioselective method is described for the quantitation of the reboxetine (R,R)- and (S,S)-enantiomers in plasma utilizing solid-phase extraction, derivatization, normal-phase high-performance liquid chromatography, and fluorescence detection. Plasma samples (0.1 ml) with added internal standard were applied to activated solid-phase extraction discs containing a nonpolar/strong cation mixed-phase, washed, eluted, evaporated to dryness, and derivatized for 5 min with (+)-1-(9-fluorenyl)ethyl chloroformate. After termination of the derivatization reaction, the samples were analyzed by isocratic normal-phase HPLC using a silica column and ethanol-heptane (1:124, v/v) as mobile phase. The derivatized reboxetine peak was column-switched onto cyano and Chiralcel OD-H columns in series using ethanol-heptane (1:49, v/v) as mobile phase to resolve the diastereomeric derivatives of the enantiomers and separate interferences. The column effluent was monitored with fluorescence detection at 260/315 nm. The range of quantitation of each enantiomer was 2-2000 ng/ml. One sample was injected every 18 min.

Adrenergic Uptake Inhibitors↗