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PubMed1996

Determination of glibenclamide in human plasma by solid-phase extraction and high-performance liquid chromatography.

A sensitive high-performance liquid chromatographic method for determination of intact glibenclamide in human plasma has been developed. Sample clean-up prior to chromatographic analysis was accomplished by extraction of the drug using a solid-phase RP-8 or RP-18 cartridge instead of the conventional liquid-liquid extraction methods described. For the separation of the drug from the endogenous components a reversed-phase column (LiChrosorb RP-8) of 5 microns particle size and 250 x 4 mm I.D., together with a mobile phase consisting of aceronitrile-12 mM perchloric acid (47:53) was selected. The method employs progesterone as an internal standard, and a reversed-phase column combined with UV detection of the drug at 230 nm. The detector response was linear up to the concentration of 400 ng/ml and the average recovery was 100.36%. The sensitivity of the method was 5 ng/ml.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Determination of flunitrazepam and its main metabolites in serum and urine by HPLC after mixed-mode solid-phase extraction.

A rapid and sensitive method is presented for the simultaneous determination of flunitrazepam, norflunitrazepam, 7-aminoflunitrazepam, and 7-acetamidoflunitrazepam in serum, plasma, and urine. The compounds were extracted by a mixed-mode solid-phase procedure following analysis by high-performance liquid chromatography and ultraviolet detection and using methylclonazepam as the internal standard. The method revealed high recoveries and showed good precision and linearity for all compounds. The limit of detection was at least 1 ng/ml serum (plasma) for all compounds.

Anti-Anxiety Agents↗
PubMed2001

Trace level analysis of polycyclic aromatic hydrocarbons in surface waters by solid phase extraction (SPE) and gas chromatography-ion trap mass spectrometry (GC-ITMS).

Ontario Provincial Water Quality Objectives for polycyclic aromatic hydrocarbons (PAHs) in surface waters require low parts per trillion (ng L(-1))/high parts per quadrillion (pg L(-1)) detection limits. To meet these monitoring requirements, a solid phase extraction-gas chromatography-ion trap mass spectrometry (SPE-GC-ITMS) method was developed. Seventeen priority PAHs commonly monitored in surface and drinking waters were examined using an external ionization ion trap mass spectrometer operated in selected ion monitoring (SIM) mode. Under 70 eV electron ionization (El) conditions, both the quantitative [M]+* ion and confirmatory [M - 2H]+* ion were formed in classical abundance ratios. Each of these ion species was isolated in the ion trap using a specific scan function. However, to overcome poor levels of confirmatory ion abundance which otherwise restrict PAH method detection limits (MDLs), the abundance of [M - 2H]+* ions was augmented during isolation by causing the dissociation of [M]+* with the broad-band waveform used for high mass ion ejection. Augmenting the [M - 2H]+* signal intensity facilitated the achievement of MDLs of approximately 1 ng L(-1). PAHs in surface water samples that were not detected by current Ontario Ministry of the Environment high-performance liquid chromatography (HPLC)-fluorescence and GC-single-stage quadrupole mass spectrometry methods were detected and quantified using the ion trap mass spectrometry SIM method. The data produced by all three methods on natural water samples fortified at sub-parts per billion (ppb) levels were comparable. When applied to Standards Council of Canada/Canadian Association for Environmental Analytical Laboratories (SCC/CAEAL, www.CAEAL.ca) accreditation audit samples, the SPE-GC-ITMS method results met all performance evaluation criteria.

Gas Chromatography-Mass Spectrometry↗
PubMed2000

Flow injection analysis with in-line solid phase extraction for the spectrophotometric determination of sulfonated and unsulfonated Quinoline Yellow in Cologne.

An integrated solid-phase spectrophotometry/ FIA method is proposed for the determination of the synthetic colorant matter Quinoline Yellow (QYWS) in the presence of its unsulfonated derivative QYSS. The procedure is based on the retention and preconcentration of the low level QYSS on a C-18 silica gel minicolumn, followed by sequential measurement of its absorbance at lambda = 410 nm after its elution with methanol. The applicable concentration range, the detection limit and the relative standard deviation were the following: for QYWS, from 0.10 to 30.0 mg L(-1); 0.013 mg L(-1); and 0.6%; and for QYSS, between 10 and 1.000 microg L(-1); 2 microg L(-1); and 1.3%, respectively. The method was applied to the determination of small amounts of QYSS present in QYWS in Colognes. Percentages of recovery between 98% and 99% were obtained in all instances. The method was also satisfactorily applied to the determination of these compounds in samples of commercial Colognes comparing the results for QYWS with those offered by an HPLC reference method and also validating the results chemometrically.

Journal Article↗
PubMed1992

Determination of fluconazole in human serum by solid-phase extraction and reversed-phase high-performance liquid chromatography.

A simple, rapid, and accurate reversed-phase octadecylsilyl high-performance liquid chromatographic method using solid-phase column extraction is described for measuring fluconazole in human serum. The column eluent was monitored by ultraviolet absorption at 210 nm. Fluconazole was extracted from diluted serum by adsorption on a small Bond-Elut C18 cartridge after the addition of UK48,134 as the internal standard and recovered by elution with methanol. The methanol was then evaporated to dryness and the residue reconstituted in 200 microliters of mobile phase and filtered prior to injecting an aliquot (50 microliters) onto an Adsorbosphere C18 column (4.6 x 250 mm, 5 microns particle size), using a mobile phase of 25 mM tris(hydroxymethyl)aminomethane-phosphate buffer (pH 7.0):acetonitrile (75:25, vol/vol). The retention times were 6.6 min for fluconazole and 9.0 min for the internal standard. The assay was precise, with inter- and intraassay coefficients of variation of less than or equal to 2.9% and less than or equal to 2.1%, respectively, and with good linearity (r = 1.000) in the range of 0.1 to 25 micrograms/ml. The duration of each analysis was 15 min and the minimum detectable serum concentration was 0.1 microgram/ml.

Administration, Oral↗
PubMedDate not supplied

Solid-phase extraction of carbofuran, atrazine, simazine, alachlor, and cyanazine from shallow well water.

Extraction of several nitrogen-containing pesticides from water on solid-phase C18 cartridges was rapid and accurate. One analyst can extract greater than 48 samples/day. Recovery efficiencies were 77, 95, 92, 90, and 99% with detection limits of 0.20, 0.05, 0.05, 0.20, and 0.10 micrograms/L for carbofuran, atrazine, simazine, alachlor, and, cyanazine, respectively. Extraction of the atrazine and simazine dealkylation products (deethylatrazine and deethylsimazine) was less efficient, e.g., 26 and 9%, respectively. Comparisons with 10 U.S. Geological Survey samples gave similar results.

Acetamides↗
PubMed2005

Application of solid phase extraction and high-performance liquid chromatography to qualitative and quantitative analysis of nucleotides and nucleosides in human cerebrospinal fluid.

New method of qualitative and quantitative analysis of nucleotides in human cerebrospinal fluid (CSF), based on the combination of extraction of purines and pyrimidines to the solid phase (SPE) and high-performance liquid chromatography (HPLC), was proposed. Use of SPE and lyophilization of samples allowed for the first time to detect the presence of di- and triphosphonucleotides in human CSF. Concentration of those compounds varied from 0.003 to 5.0 microM. Differences in the nucleotide mixture composition in human CSF detected with the new method are coupled with the neurological disorders and might be a basis for an efficient diagnostic tool.

Chromatography, High Pressure Liquid↗
PubMed2000

Fully automated determination of eserine N-oxide in human plasma using on-line solid-phase extraction with liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

A sensitive and entirely automated solid-phase extraction/liquid chromatography/electrospray ionization tandem mass spectrometric (SPE/LC/ESI-MS/MS) method was developed and validated for the determination of eserine N-oxide (ENO), a cholinesterase inhibitor-like physostigmine in human plasma, for use in pharmacokinetic studies. ENO is light-sensitive and the use of a fully on-line process increased the reliability of the assay. Plasma samples previously mixed with neostigmine bromide to prevent in vitro degradation, and tacrine as internal standard (IS), were directly injected into the SPE/LC/ESI-MS/MS system. MS software piloted the overall system. MS/MS detection of ENO and the IS was performed in the positive ion ESI mode using multiple reaction monitoring. The linear calibration curve for ENO ranged from 25 pg ml(-1) to 12.5 ng ml(-1). The limit of quantitation was 25 pg ml(-1) with 250 microl of plasma injected. Precision, accuracy and stability tests were within the acceptable range and just one analyst is required to analyze 50 unknown samples a day five days per week, from the preparation of the samples (i.e. thawing and centrifugation) to data processing. A pilot pharmacokinetic study in three healthy volunteers treated with 4.5 mg of ENO (Génésérine3((R))) showed that the method was suitable for pharmacokinetic studies in humans.

Chromatography, High Pressure Liquid↗
PubMed1998

Capillary electrophoresis of insulin-like growth factors: enhanced ultraviolet detection using dynamically coated capillaries and on-line solid-phase extraction.

Insulin-like growth factor-I and -II (IGF-I and IGF-II) are difficult to separate and measure as a result of their homology, both structurally and immunologically. A number of binding proteins (BPs) which interact with the IGFs with high affinity complicate the ability to measure the IGFs accurately and reproducibly. Current methodology for measuring IGF is immuno-based and involves dissociation from the IGFs and removal of the binding proteins through sample acidification and removal by solid-phase adsorption. However, the net result is an assay that is time-consuming and, at best, semiquantitative. In an attempt to improve the reproducibility and accuracy of IGF-I and -II measurement, electrophoretic systems employing dynamically coated and bare silica capillaries were evaluated. Separations in bare silica capillaries in the presence or absence of the cationic additive, decamethonium bromide were ineffective for resolving IGF-I and IGF-II. However, when the capillary was coated dynamically with polybrene, IGF-I and -II could be resolved in a BSA sample matrix using a low pH buffer. Despite the fact that the IGFs could be resolved in the presence of an IGF-I analog used as an internal standard, polybrene recoating was required after as few as 12 runs and poor coating-to-coating reproducibility was observed. Use of polydiallyldimethylammonium chloride (PDMAC) as a dynamic cationic coating and a low pH buffer containing 0.5% PDMAC was found to be much more effective, providing reproducible separation of IGF-I and -II. It was found that PDMAC need not be included in the separation buffer to obtain reproducible analyses regarding IGF separation. Subsequently, functionality remained intact for as many as 35-40 consecutive analyses before recoating was required. Without the need for PDMAC in the buffer, on-line solid-phase extraction-capillary electrophoresis could be accomplished for detection of IGF-I and -II at concentrations as low 195 ng/ml.

Buffers↗
PubMedDate not supplied

Quantitation of cimetidine and cimetidine sulfoxide in serum by solid-phase extraction and solvent-recycled liquid chromatography.

A high performance liquid chromatographic method for the simultaneous determination of cimetidine and its major metabolite, cimetidine sulfoxide, was developed. These compounds and the internal standard, ornidazole, were extracted from 0.5 mL of serum using a solid phase Bond Elut C18 analytical column with detection at 229 nm. Absolute recoveries were 94 to 103%, 93 to 104%, and 95 to 105% for cimetidine, cimetidine sulfoxide, and ornidazole, respectively. The minimum detection limit for cimetidine was 0.1 mg/L and for cimetidine sulfoxide was 0.05 mg/L when the concentrating step was used. Cimetidine and cimetidine sulfoxide demonstrated linearity up to 10 mg/L and 7.5 mg/L respectively, with the between-run precision of less than a 5% coefficient of variation for both compounds. Interferences from other drugs tested or endogenous substances in serum were not detected. The mobile phase was recycled to maintain better long term column stability and to minimize solvent cost. The instability of the drugs in solution was circumvented with a reduced-pressure drying process that produced working standards possessing longterm stability. The problem of drug interconversion observed during sample storage and with concentrating steps was controlled also. In addition, a resolution test mixture was chromatographed daily to control chromatographic quality.

Chromatography, High Pressure Liquid↗
PubMed1996

Determination of gabapentin in serum using solid-phase extraction and gas-liquid chromatography.

A gas-liquid chromatographic method for the determination of gabapentin (Neurontin) is described. The method involves extracting 0.5 mL of acidified sample by C18 solid-phase column, derivatization with MTBSTFA plus 1% tBDMCS, and analysis on an HP-1 column with a flame-ionization detector. Quantitation was performed with peak-height ratios of gabapentin to a gabapentin analogue [(1-aminomethyl-1-cycloheptyl) acetic acid] as the internal standard. The assay had a limit of detection of 0.2 mg/L and a linear range from 0.5 to 30.0 mg/L. Several compounds were analyzed for potential interference, and none interfered with the assay.

Acetamides↗
PubMed1993

Solid-phase extraction technique for gas-chromatographic profiling of acylcarnitines.

We present a simple, new clean-up method for the gas-chromatographic profiling analysis of acylcarnitines. The use of a solid-phase, cation-exchange extraction combined with gas-chromatographic separation, based on the derivatization into acyloxylactones by Lowes and Rose (Analyst 1990;115:511-6), allows a selective and sensitive screening for acylcarnitines in urine. As such, a quantitative approach was developed for differential evaluation of acylcarnitines for detection of inborn errors of metabolism; the evaluation is both fast and routinely applicable in any biochemical laboratory. We validate the analysis method for acylcarnitines of various chain-lengths and present examples of its application to urine samples from diseased patients. We give special attention to the medium-chain acylcarnitines because of their association with medium-chain acylCoA dehydrogenase deficiency. Finally, the quantitative nature of the analysis allows evaluation of the acylcarnitine excretion over time.

Adult↗
PubMed1997

Analysis of benzalkonium chloride in the effluent from European hospitals by solid-phase extraction and high-performance liquid chromatography with post-column ion-pairing and fluorescence detection.

A highly reproducible and specific method for the analysis of the quaternary ammonium compound, benzalkonium chloride, in effluents from European hospitals is presented. Benzalkonium chloride was extracted with end-capped RP-18 solid-phase cartridges and was selectively eluted. The resulting solution was analyzed by high-performance liquid chromatography (HPLC). After elution from the analytical column of the HPLC system, 9,10-dimethoxyanthracene-2-sulfonate was added continuously as a fluorescence marker, forming a hydrophobic ion-pair with benzalkonium chloride. The ion-pair was analyzed by fluorescence detection. The method was applied to highly complex effluent samples from different sized European hospitals. The measured concentrations were between 0.05 and 6.03 mg/l. The amounts emitted per bed and year were 4.5-362 g and did not correlate with the size of the hospital. The total amounts were 2.6-909 kg/year.

Anthracenes↗
PubMed2005

Determination of itraconazole in human plasma by high-performance liquid chromatography with solid-phase extraction.

BACKGROUND: A practical, simple, high-performance liquid chromatographic (HPLC) method is needed for the determination of itraconazole in clinical plasma samples. METHODS: Itraconazole and bifonazole (internal standard) were extracted from plasma using a C8-bonded solid-phase cartridge, separated by C8 reversed-phase HPLC, and quantified by ultraviolet absorption at 263 nm. RESULTS: This new method enabled the determination of itraconazole in the concentration range of 10.0-500.0 microg/L. The detection limit of itraconazole was 5.0 microg/L. The mean recovery of itraconazole added to plasma was more than 89.1%, with a coefficient of variation of less than 6.9%. We applied this method for the determination of plasma itraconazole in volunteers treated daily with a 200 mg oral capsule of itraconazole for four days. We monitored the plasma level of itraconazole for the following 24 h and obtained the mean area under the plasma concentration-time curve from 0 to 24 h (AUC(0-24) ) value of 4358.9 +/- 1933.4 microg h/L. CONCLUSION: Our new method will be clinically useful for accurately monitoring the plasma concentration of itraconazole in patients under treatment.

Adult↗
PubMed2003

Ion suppression in the determination of clenbuterol in urine by solid-phase extraction atmospheric pressure chemical ionisation ion-trap mass spectrometry.

Ion suppression effects were observed during the determination of clenbuterol in urine with solid-phase extraction/multiple-stage ion-trap mass spectrometry (SPE/MS(3)), despite the use of atmospheric pressure chemical ionisation. During SPE, a polymeric stationary phase (polydivinylbenzene) was applied. Post-cartridge infusion of analyte to the SPE eluate after the extraction of blank urine was performed to obtain a profile of the suppression. Single and multiple-stage MS were performed to provide insight in the suppressing compounds. The ion suppression was mainly ascribed to two m/z values, but still no identification of the compounds was achieved from the multiple-stage MS data. No ionisable and non-ionisable complexes and/or precipitation of clenbuterol with matrix compounds were observed. A concentration dependence of the percentage of suppression was observed. Up to 70% of the signal was suppressed upon post-cartridge infusion of 0.22 microg/mL (at 5 microL/min) clenbuterol into the eluate, and this decreased to about 4% at infusion of 22 microg/mL clenbuterol. Molecularly imprinted polymers were used to enhance the selectivity of the extraction. Although matrix components were still present after extraction, no interference of these compounds with the analyte was observed. However, the bleeding of the imprint from the polymer (brombuterol) caused significant ion suppression.

Animals↗
PubMed2001

Determination of alkylbenzyldimethylammonium chlorides in river water and sewage effluent by solid-phase extraction and gas chromatography/mass spectrometry.

This study presents a modified method to analyze alkylbenzyldimethylammonium chlorides (ABDACs) in river water and sewage effluent. The method involves mixed samples with linear alkylbenzenesulfonates (LAS) as a counterion to enhance the extraction of ABDAC residues from an RP-18 solid-phase cartridge by formation of hydrophobic ion-pair complexes. The ABDACs were then eluted with methanol-ethyl acetate (1:1, v/v) and formed to their corresponding alkyldimethylamines by the Hofmann degradation with potassium tert-butoxide. The alkyldimethylamines were then identified and quantitated by gas chromatograph/mass spectrometry (GC/MS). The results indicate that, in the presence of LAS, debenzylation of ABDACs occurs selectively at a temperature higher than 90 degrees C to produce the corresponding nonionic alkyldimethylamines. The method proposed herein provides a high precision and sensitivity for ABDACs, to quantitation at < or =0.1 microg/L in 500 mL of the water samples. The average recovery of ABDAC spiked water samples was 95% with relative standard deviations (RSD, n = 7) of 9%. The RSDs of three replicate environmental sample analyses ranged from 5 to 11%. Direct HPLC method was applied to evaluate the GC/MS method, and compatible results were observed.

Journal Article↗
PubMed2006

Sequential separation of lanthanides, thorium and uranium using novel solid phase extraction method from high acidic nuclear wastes.

A novel grafted polymer for selective extraction and sequential separation of lanthanides, thorium and uranium from high acidic wastes has been developed by grafting Merrifield chloromethylated (MCM) resin with octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) (MCM-CMPO). The grafting process is well characterized using FT-IR spectroscopy, (31)P and (13)C CPMAS (cross-polarized magic angle spin) NMR spectroscopy and CHNPS elemental analysis. The influence of various physico-chemical parameters during metal ion extraction by the resin phase are studied and optimized by both static and dynamic methods. The resin shows very high sorption capacity values of 0.960mmolg(-1) for U(VI), 0.984mmolg(-1) for Th(IV), 0.488mmolg(-1) for La(III) and 0.502mmolg(-1) for Nd(III) under optimum HNO(3) medium, respectively. The grafted polymer shows faster rate exchange kinetics (<5min is sufficient for 50% extraction) and greater preconcentration ability, with reusability exceeding 20 cycles. During desorption process, sequential separation of the analytes is possible with varying eluting agents. The developed grafted resin has been successfully applied in extracting Th(IV) from high matrix monazite sand, U(VI) and Th(IV) from simulated nuclear spent fuel mixtures. All the analytical data is based on triplicate analysis and measurements are within 3.5% rsd reflecting the reproducibility and reliability of the developed method.

Lanthanoid Series Elements↗