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PubMed1995

A liquid chromatographic method for the determination of promethazine enantiomers in human urine and serum using solid-phase extraction and fluorescence detection.

A LC method was developed for the concurrent assay of R(+) and S(-) promethazine from human urine and serum. The method involves the use of solid-phase extraction for sample clean-up. Chromatographic resolution of the enantiomers was performed under isocratic conditions using a mobile phase of hexane-1,2-dichlorethane-absolute ethanol-trifluoroacetic acid (400:150:100:1, v/v/v/v) at a flow rate of 1 ml min-1 on a brush-type column KK-CARNU. The enantiomers were detected by fluorescence using an excitation wavelength of 250 nm and a 280 nm emission cutoff filter. Chlorpromazine was used as the internal standard for urine analysis. Standard addition was used for promethazine analysis from serum. Drug to internal standard ratios were linear from 0.25 to 10 micrograms ml-1 in urine. Serum levels were linear from 2 to 10 ng ml-1.

Chlorpromazine↗
PubMed2004

Solid-phase extraction of polar compounds with a hydrophilic copolymeric sorbent.

A new synthesized copolymer based on N-vinylimidazole-divinylbenzene (VIm-DVB) was tested as a sorbent for the solid-phase extraction (SPE) of polar analytes. In the on-line SPE, this synthesized sorbent enabled 100 ml of sample to be preconcentrated with recoveries as high as 80% for oxamyl, phenol (Ph) and derivates, bentazone and (4-chloro-2-methylphenoxy)acetic acid (MCPA). For the off-line SPE, 1000 ml of sample was extracted and recoveries were higher than 92% for all compounds with the exception of oxamyl (83%) and methomyl (78%). The VIm-DVB sorbent gives better recoveries than the previously synthesized 4-vinylpyridine-divinylbenzene (VP-DVB) resin and similar to such highly crosslinked commercial sorbents as LiChrolut EN or Oasis HLB. Real water samples were used to validate the on-line SPE method. Linearity was good and detection limits were between 0.1 and 0.2 microg l(-1).

Imidazoles↗
PubMed2000

Mixed-level orthogonal array design for the optimization of solid-phase extraction of some pesticides from surface water.

An orthogonal array design (OAD), OA32(4(1) x 2(28)), was employed as a chemometric method for the optimization of the solid-phase extraction (SPE) of atrazine, diazinon, ametryn and fenthion in surface water. Seven parameters: the type of eluting solvent, type of sorbent, flow-rate of eluting solvent, sample pH, sample volume, elution volume, addition of modifier and flow-rate of water sample were studied and optimized by a mixed-level OAD. The effects of these factors and some two-variable interactions on the recovery of the pesticides were quantitatively evaluated by the analysis of variance and percentage contribution techniques. The final optimized condition was employed for the SPE of selected micro-organic pollutants from Karoun river water, south of Iran. Atrazine and ametryn were tentatively identified and determined at the 0.7 and 0.9 microg l(-1) level, respectively.

Chromatography, Liquid↗
PubMed2000

On-line coupling of solid-phase extraction to gas chromatography with fast solvent vaporization and concentration in an open injector liner. Analysis of pesticides in aqueous samples.

The purpose of this study is to combine solid-phase extraction (SPE) with gas chromatography (GC) for the fully automated determination of pesticides and herbicides in aqueous samples. The interface technique employed for connecting SPE with GC was fast solvent vaporization and concentration in an open injector liner. The interface device consisted of the programmed-temperature vaporizing injector without using the packing material in the liner and the target compounds were concentrated around the inlet of the GC capillary column. This avoided the degradation of target compounds, and no precise control of the injecting speed was required, when an automatic SPE system was connected to GC-MS. The aqueous samples used in this system were prepared by spiking 29 kinds of pesticide and herbicide compounds, which are regulated by the Ministry of Health and Welfare of the Japanese National government, in purified water and river water, to a resulting concentration of 1 microg/l. Employing this system, the recoveries and RSDs (n=6) of most compounds were greater than 75% and within 10%, respectively. From the results of this study, we found that on-line automatic SPE and capillary GC-MS equipped with the fast solvent vaporizing and concentrating method in an open injector liner could be connected in order to obtain good results for the determination of pesticides in water samples.

Chromatography, Gas↗
PubMed1997

Solid-phase extraction and determination of ranitidine in human plasma by a high-performance liquid chromatographic method utilizing midbore chromatography.

An improved high-performance liquid chromatographic (HPLC) method utilizing solid-phase extraction (SPE) and midbore chromatography was developed for the determination of ranitidine in human plasma. A mobile phase of 20 mM K2HPO4-acetonitrile-triethylamine (87.9:12.0:0.1, v/v) pH 6.0 was used with a phenyl analytical column and ultraviolet detection (UV). The method demonstrated linearity from 25 to 1000 ng/ml in 500 microliters of plasma with a detection limit of 10 ng/ml. The method was utilized in a pharmacokinetic study evaluating the effects of pancreatico-biliary secretions on ranitidine absorption.

Anti-Ulcer Agents↗
PubMed1997

Quantitation of trimipramine enantiomers in human serum by enantioselective high-performance liquid chromatography and mixed-mode disc solid-phase extraction.

A sensitive and stereospecific method for the quantitation of trimipramine enantiomers in human serum was developed. The assay involves the use of a novel mixed-mode disc solid-phase extraction for serum sample clean-up prior to HPLC analysis and is also free of interference from the enantiomers of desmethyltrimipramine, 2-hydroxytrimipramine, and 2-hydroxydesmethyltrimipramine, the three major metabolites of trimipramine. Chromatographic resolution of trimipramine enantiomers was performed on a reversed-phase cellulose-based chiral column (Chiralcel OD-R) under isocratic conditions using a mobile phase consisting of 0.3 M aqueous sodium perchlorate-acetonitrile (58:42, v/v) at a flow-rate of 0.5 ml/min. Recoveries for R- and S-trimipramine enantiomers were in the range of 93-96% at 25-185 ng/ml levels. Intra-day and inter-day precisions calculated as R.S.D. were in the ranges of 0.30-8.00% and 1.60-10.20% for both enantiomers, respectively. Intra-day and inter-day accuracies calculated as percent error were in the 0.01-2.10% and 1.00-3.00% ranges for both enantiomers, respectively. Linear calibration curves were in the concentration range 15-250 ng/ml for each enantiomer in serum. The limit of quantification of each enantiomer was 15 ng/ml. The detection limit for each enantiomer in serum using a UV detector set at 210 nm was 10 ng/ml (S/N=2). In addition, separation of the enantiomers of desmethyltrimipramine, 2-hydroxytrimipramine, and 2-hydroxydesmethyltrimipramine were investigated. The desmethyltrimipramine enantiomers could be resolved on the Chiralcel OD-R column under the same chromatographic conditions as the trimipramine enantiomers, but the other two metabolite enantiomers required different mobile phases on the Chiralcel OD-R column to achieve satisfactory resolution with Rs values of 1.00.

Antidepressive Agents, Tricyclic↗
PubMed1998

At-line solid-phase extraction for capillary electrophoresis: application to negatively charged solutes.

The analysis of complex biological samples with capillary electrophoresis (CE) requires proper sample pretreatment. In this paper the applicability of solid-phase extraction (SPE) coupled at-line with CE is studied, by using a laboratory-made interface. A fresh (disposable) SPE cartridge is used for each sample to prevent carry-over effects. The sample handling procedure is performed parallel with the analysis of the previous sample, to improve sample throughput. Using this set-up, negatively charged test compounds (some non-steroid anti-inflammatory drugs) can be determined in serum and urine. The method is linear over at least two decades and detection limits are around 40 microg/l. A single capillary, flushed only once a week with a sodium hydroxide solution, was used without problems for the analysis of ca. 900 samples during 1 year. The robustness of the system was very good: no blocking of loop, interface or capillary was found during this period. Furthermore, the system was successfully used for overnight runs.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1997

Simultaneous solid-phase extraction on C18 cartridges of opiates and cocainics for an improved quantitation in human hair by GC-MS: one year of forensic applications.

We have developed a new solid-phase extraction (SPE) on C18 cartridges which allows a very simple protocol of manipulation and a single elution of opiates and cocainics from human hair samples. The method involved decontamination in a phosphate buffer and dichloromethane, pulverization in a ball mill, addition of deuterated internal standards, heated acid hydrolysis and SPE. Quantitation utilized gas chromatography and mass spectrometry. Between days precise study gave relative standard deviations always inferior to 8.9% for each compound at 4 ng/mg (except methylecgonine ester = 15.7%). Accuracy was tested using a t-statistic versus a reference material from the NIST. Limits of detection were calculated from an analysis of the blanks which contained between 0.12 and 0.28 ng/mg for each drug. The method was applied in forensic cases for 1 year of toxicological activity. Among the 108 analyses performed, 30 were positive for cocaine and 33 for opiates. Concentrations were in the range 0.9-242.0 ng/mg (cocaine), 0.3-71.3 ng/mg (benzoylecgonine), 0.0-9.8 ng/mg (methylecgonine ester), 0.0-2.9 ng/mg (cocaethylene), 0.1-11.5 ng/mg (codeine), 0.4-44.6 ng/mg (morphine) and 0.7-131.2 ng/mg (6-acetylmorphine). Ratios of the metabolites to parent drugs were proposed to avoid risk of external contamination.

Cocaine↗
PubMed1997

Quantitation of promethazine enantiomers in human serum using a chiralcel OJ-R column and mixed-mode disc solid-phase extraction.

A liquid chromatographic method was developed for the assay of R(+)- and S(-)-promethazine enantiomers from human serum. The method involves the use of the mixed mode disc solid-phase extraction technique for sample clean-up. Chromatographic resolution of the enantiomers was performed on a reversed-phase cellulose-based chiral column (Chiralcel OJ-R) under isocratic conditions using a mobile phase consisting of 0.5 M aqueous sodium perchlorate/acetonitrile (63:37, v/v) at a flow rate of 0.5 ml min-1. Recoveries in the range of 97-99% at 20 ng ml-1 levels were obtained for both promethazine enantiomers. Intra-day and inter-day precision calculated as R.S.D.% was in the 3-8% ranges for both enantiomers. Intra-day and inter-day accuracy calculated as percent error was in the 0-10 and 1-7% ranges for both enantiomers, respectively. Linear calibration curves were obtained for each enantiomer in serum in the concentration range 5-90 ng ml-1. The limit of quantitation of each enantiomer was 10 ng ml-1. The detection limit for each enantiomer in serum using UV detection at 249 nm was 2 ng ml-1 (S/N = 2).

Anti-Allergic Agents↗
PubMed1997

Determination of pyrrolizidine alkaloids in honey from selected sites by solid phase extraction and HPLC-MS.

A method was developed for the determination in honey of the Ragwort (Senecio jacobaea) derived pyrrolizidine alkaloids jacoline, jacozine, jacobine, seneciphylline and senecionine, combining solid-phase extraction with high performance liquid chromatography and atmospheric pressure chemical ionization mass spectrometric detection. The method allowed determination of individual alkaloids and offered a considerable improvement in terms of speed, sensitivity and specificity over previous approaches, but was not suitable for determination of jaconine, a minor alkaloid in Ragwort. Instrument calibrations were linear over the range 0.005 to 100 micrograms/ml, equivalent to approximately 0.001 to 2.0 mg/kg in honey with the extraction method used and allowing for observed recoveries. Detection limits in honey were 0.002 mg/kg. Recoveries for most of the alkaloids were between 57 and 70%. The alkaloids have been determined in a number of samples of honey selected after pollen identification and counting. The alkaloids were not detectable in samples containing two grains or less of Ragwort pollen per gram of honey. Samples collected in late July and August contained Ragwort pollen at 15-21 grains/g and total alkaloid concentrations of 0.011-0.056 mg/kg. Similar contributions to the total were made by jacozine, seneciophylline and senecionine, with jacobine making a larger and jacoline a smaller contribution. Two samples of honey containing Ragwort pollen at 24 and 16 grains/g had total alkaloid concentrations of 0.42 and 1.48 mg/kg respectively (not corrected for recovery). The alkaloid profile in these samples was dominated by seneciphylline and senecionine which together comprised 90-95% of the total. Alkaloids were not detected in retail honeys.

Chromatography, High Pressure Liquid↗
PubMed2005

Quantitative determination of incarvillateine in Incarvillea sinensis by solid phase extraction and high performance liquid chromatography.

Method for rapid quantitative analysis of incarvillateine in Incarvillea sinensis by high-performance liquid chromatography (HPLC) has been developed. The sample preparation involves solid phase extraction (SPE) with a mixed-mode reversed-phase and cation-exchange cartridge. The linear calibration range for incarvillateine was 0.002-0.5 mg/ml. The limit of detection was 0.35 microg/ml (S/N=3). Intra- and interday precisions were less than 0.36% (n=6) and 1.61% (n=18), respectively. The recovery of incarvillateine was 97.61-102.44% with the relative standard deviation (RSD) ranging from 0.63 to 1.93% (n=3). This method was proposed as a simple, rapid and accurate method for quantitative determination of incarvillateine content in various samples of Incarvillea sinensis collected from different areas of China.

Alkaloids↗
PubMed2003

Solid-phase extraction of several phthalate esters from environmental water samples on a column packed with polytetrafluoroethylene turnings.

A method for the determination of several phthalate esters in water samples using solid-phase extraction coupled to high-performance liquid chromatography was developed. A polytetrafluoroethylene turnings packed column was used as a SPE adsorbent material. The analytes were sorbed on polytetrafluoroethylene turnings, from which they were eluted by a small amount of acetonitrile, followed by a RP-HPLC-UV analysis. Detection limits (3sigma) of 4.7, 3.1, 3.6, 4.3, and 5.8 ng mL(-1) for di-n-butyl-phthalate, di-cyclohexyl-phthalate, di-n-octyl-phthalate, di-n-nonyl-phthalate and di-iso-decyl-phthalate, respectively, were achieved. Acceptable recovery results (92.1-127.5%) were obtained on five phthalate esters spiked samples.

Journal Article↗
PubMedDate not supplied

Stability of pesticides on solid-phase extraction disks after incubation at various temperatures and for various time intervals: interlaboratory study.

An interlaboratory study was conducted at 8 locations to assess the stability of pesticides on solid-phase extraction (SPE) disks after incubation at various temperatures and for various time intervals. Deionized water fortified with selected pesticides was extracted by using 2 types of SPE filtration disks (Empore C18 and Speedisk C18XF), and after extraction, the disks were incubated at 3 temperatures (25, 40, and 55 degrees C) and for 2 time intervals (4 and 14 days). Deionized water was fortified with atrazine, carbofuran, and chlorpyrifos by all participating laboratories. In addition, some of the laboratories included 2 of the following pesticides: metolachlor, metribuzin, simazine, chlorothalonil, and malathion. Concurrently, fortified water samples were extracted with the incubated samples by using each disk type at 4 and 14 days. Pesticides had equivalent or greater stability on > or = 1 of the C18 disk types, compared with storage in water. The lowest recoveries of carbofuran (6%) and chlorpyrifos (7%) were obtained at 55 degrees C after storage for 14 days in incubated water. At 55 degrees C after 14 days, the lowest recovery for atrazine was 65% obtained by using Empore disks. Pesticide-specific losses occurred on the C18 disks in this study, underlining the importance of temperature and time interval when water is extracted at remote field locations and the SPE disks containing the extracted pesticides are transported or shipped to a laboratory for elution and analysis.

Calibration↗
PubMed1989

Analysis of supplemented vitamin K1(20) in serum microsamples by solid-phase extraction and narrow-bone HPLC with multichannel ultraviolet detection.

A sensitive method for the determination of vitamin K1(20) in serum microsamples (50 microL) has been developed, utilizing solid-phase extraction with C8 Bond-Elut columns and reversed-phase narrow-bore high-performance liquid chromatography [2.1 mm (i.d.), column] with a nonaqueous eluent. Recovery from serum (49 ng/mL) was 76% (n = 2). Peak homogeneity was assessed by photodiode array detection with absorbance ratio, spectral normalization, and transformation to the first- and second-derivative chromatograms. Calibration data at 248 nm over two ranges (20-200 ng/mL, 200-4000 ng/mL) varied linearly with concentration and were suitable for studies of vitamin K1 supplementation. By comparison with conventional columns, sensitivity was increased twofold.

Chromatography, High Pressure Liquid↗
PubMed2002

Integration of solid-phase extraction membranes for sample multiplexing: application to rapid protein identification from gel-isolated protein extracts.

The present report describes the design and application of a dual sprayer system for high-throughput proteome analysis. This system comprises parallel solid-phase extraction cartridges used for preconcentration and desalting of proteolytic digests prior to nanoelectrospray mass spectrometry analyses. Tryptic peptides from in-gel digest of protein bands/spots are first adsorbed on styrene divinyl benzene membrane and subsequently eluted with a short plug of organic buffer prior to infusion to the mass spectrometer at a flow rate of typically 500 nL/min. Tryptic peptide eluting from the membrane are analyzed by the mass spectrometer by moving in turn each sprayer in front of the sampling orifice. Sequential injection, preconcentration and analyses of tryptic digests are typically achieved with a throughput of up to 3.5 min/sample and a detection limit of approximately 8-80 fmol per injection. Replicate injections of peptide mixtures indicated that reproducibility of peak areas ranged from relative standard deviations (RSD) of 1.1% to 4.5%. The application of this device is demonstrated for digests of gel-isolated proteins obtained from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) separation of rat liver plasma membrane and from two-dimensional gel electrophoresis of total cell lysate extracts from human prostatic cancer cell.

Angiotensin I↗
PubMed1997

Rapid determination of 1,4-dioxane in water by solid-phase extraction and gas chromatography-mass spectrometry.

A highly sensitive and accurate gas chromatography-mass spectrometry method for rapidly quantitative analysis of dioxane in water samples is described. Dioxane in water sample was extracted by hexane-methylene chloride (80:20, v/v) then transferred to a C18 solid-phase extraction (SPE) cartridge and eluted by acetonitrile. An aliquot of this solution was analyzed by gas chromatography-mass spectrometry with electron impact ionization and selected ion monitoring (dioxane m/z 88) mode. The quantitative limit was set to be 0.05 microgram/ml with an injection volume of 2 microliters and a sample volume of 1 ml. The isotopically labelled [2H8]dioxane (m/z 96) was used as internal standard. Analysis time is approximately 6 min. The results for various kinds of SPE cartridges in this method are also discussed.

Carcinogens, Environmental↗
PubMed2004

Determination of A 3,4-diaminopyridine in plasma by liquid chromatography with electrochemical detection using solid-phase extraction.

In order to quantify a small amount of a drug, 3,4-diaminopyridine (3,4-DAP), in animal plasma samples, an analytical method was developed. It involved an extraction of 3,4-DAP and phenylephrine, used as internal standard (IS), from plasma with solid-phase extraction (SPE) on C18 cartridges. This analytical method is a hyphenated technique based on high-performance liquid chromatography with electrochemical detection (HPLC-EC) whose purpose is to obtain first a sensitive method and second a satisfying separation between 3,4-DAP and phenylephrine. The analytical method is accurate, specific, and linear between 10 and 500 g of 3,4-DAP per litre. The recovery of 3,4-DAP is estimated at 70.8% with a 95% confidence interval of (66.0 -75.6%). Intermediate precision was evaluated on three quality control samples; the intra-day precision was estimated at 13.5, 9.1, 7.8% and the inter-day precision at 17.9, 8.4, 9.3%. The limit of quantification of the method was evaluated at 10 g l-1. First toxicokinetic parameters determined on dogs plasma samples after one 3,4-DAP oral administration of 1 mg kg-1 were: Cmax=395.7 microg l-1; Tmax =15 min; t1/2=113.6 min; Clearance/F=16.8 ml kg-1 min-1 and Vd/F=2.7 l kg -1.

4-Aminopyridine↗