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PubMed1989

A comparison of silica and alumina columns for high-performance liquid chromatographic separations of basic drugs and plasma constituents following on-line solid-phase extraction with column switching.

A comparison has been made of a silica and an alumina column with respect to retention behaviour in high-performance liquid chromatography of pure drug solutions and plasma profiles following on-line solid-phase extraction. Using methanol-ammonium nitrate buffer (80:20, v/v) as eluent, it was found that these systems lend themselves well to the column switching technique. Increasing the pH of the mobile phase produced similar shifts in retention for basic drugs on both columns, but fewer plasma interferents are retained on the alumina column as compared to the silica column under the same operating conditions.

Aluminum Oxide↗
PubMed1990

Determination of albuterol concentrations in human plasma using solid-phase extraction and high-performance liquid chromatography with fluorescence detection.

A fast, simple, and accurate method for determining albuterol concentrations in human plasma has been developed and validated for use in routine clinical analyses. This method involves a solid-phase extraction procedure using silica cartridges and normal-phase high-performance liquid chromatography with fluorescence detection. Regression analysis showed the method was linear over the standard curve range 1-16 ng ml-1. The percent recovery for albuterol and the internal standard, bamethane, at 5 ng ml-1 was found to be greater than 90%. The newly developed method has been applied in the analysis of plasma samples from patients and healthy volunteers.

Albuterol↗
PubMed2004

Determination of perfluorooctane sulfonate, perfluorooctanoate and perfluorooctane sulfonylamide in human plasma by column-switching liquid chromatography-electrospray mass spectrometry coupled with solid-phase extraction.

We report a method for determining fluorinated organic compounds such as perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA) and perfluorooctanesulfonylamide (PFOSA) in human blood samples by column-switching liquid chromatography-electrospray mass spectrometry. The sample preparation prior to solid phase extraction (Waters Oasis HLB extraction column) involved simply mixing plasma sample with internal standard followed by centrifugation and extraction. The compounds were separated by reversed-phase chromatography with a C(8) column, and detected by mass spectrometry using selected ion monitoring in the negative mode. The average recoveries of PFOS, PFOA and PFOSA ranged from 82.2 to 98.7% (R.S.D.: from 2.0 to 5.2%, n = 6). The limits of quantitation of PFOS, PFOA and PFOSA at signal to noise (S/N = 10) were 0.5, 0.5 and 1.0 ng ml(-1). The method enables the precise determination of standards and can be applied to the detection of PFOS, PFOA and PFOSA in human plasma samples for monitoring human exposure.

Acetates↗
PubMed2005

Quantification of pravastatin in human plasma and urine after solid phase extraction using high performance liquid chromatography with ultraviolet detection.

A high performance liquid chromatography (HPLC) method for the estimation of pravastatin in human plasma and urine samples has been developed. The preparation of the samples was performed by automated solid phase extraction using clonazepam as internal standard. The compounds were separated by isocratic reversed-phase HPLC (C(18)) and detected at 239 nm. The method was linear up to concentrations of 200 ng/ml in plasma and 2000 ng/ml in urine. The intra-assay variability for pravastatin in plasma ranged from 0.9% to 3.5% and from 2.5% to 5.3% in urine. The inter-assay variability ranged from 9.1% to 10.2% in plasma and from 3.9% to 7.5% in urine. The validated limits of quantification were 1.9 ng/ml for plasma and 125 ng/ml for urine estimation. These method characteristics allowed the determination of the pharmacokinetic parameters of pravastatin after administration of therapeutic doses.

Chromatography, High Pressure Liquid↗
PubMed2000

Use of solid-phase extraction and high-performance liquid chromatography for the determination of triazine residues in water: validation of the method.

A method for determination of some triazine residues in water has been developed. The method involves concentration with C18 solid-phase extraction cartridges followed by high-performance liquid chromatographic analysis using a C18 column with UV detection at 230 nm, a mobile phase of methanol-water (60:40, v/v) at pH 4.6 (phosphoric acid) and a flow-rate of 0.8 ml/min. After optimization of the extraction and separation conditions, the method was validated. The method can be used for determination of atrazine, simazine, cyanazine and ametryn in water, within the international limits of 0.1 microg/l.

Chromatography, High Pressure Liquid↗
PubMed1996

Stereoselective determination of apomorphine enantiomers in serum with a cellulose-based high-performance liquid chromatographic chiral column using solid-phase extraction and ultraviolet detection.

A novel and rapid method for the separation and determination of R-(-)- and S-(+)-enantiomers of apomorphine in serum by high-performance liquid chromatography with UV detection is reported. The method involved a solid-phase extraction of the R-(-)- and S-(+)-enantiomers of apomorphine and the internal standard R-(-)-propylnorapomorphine from serum using a C8 Bond-Elut column. The HPLC system consisted of a reversed-phase cellulose-based chiral column (Chiralcel OD-R, 250 x 4.6 mm I.D.) with a mobile phase of 35:65 (v/v) acetonitrile-0.05 M sodium perchlorate (pH 2.0, adjusted with 60-62% perchloric acid) at a flow-rate of 0.5 ml/min with UV detection at 273 nm. The detection and quantitation limits were 10 ng/ml for each enantiomer using 1 ml of serum. Linear calibration curves from 10 to 1000 ng/ml for both R-(-)- and S-(+)-enantiomers show coefficient of determination of more than 0.9995. Precision calculated as %R.S.D. and accuracy calculated as % error were 0.2-4.7 and 3.1-6.9%, respectively, for the R-(-)-enantiomer and 1.3-4.2 and 0.3-6.8%, respectively, for the S-(+)-enantiomer.

Animals↗
PubMed2002

Solid-phase extraction and cleanup of organophosphorus pesticide residues in bovine muscle with gas chromatographic detection.

The purpose of this investigation is to develop a rapid and simple method for the assessment of organophosphorus pesticides in bovine muscle by using solid-phase extraction (SPE). After extraction with ethyl acetate (EtOAc) the homogenate is centrifuged and filtered through sodium sulfate. The fat is precipitated in methanol by cooling and the extract is diluted with water and passed through a SPE column (Isolute ENV+). After elution with EtOAc, evaporation, and redissolution, the sample is injected into a gas chromatographic (GC) capillary column DB-1701 and detected by a flame photometric detector. Recoveries from bovine muscle fortified with 12 pesticides between 4 and 65 microg/kg include three levels ranging between 59% and 109% for ten of them. The two most polar pesticides (metamidophos and acephate) are not successful. The relative standard deviations are between 1% and 10% for the ten pesticides. A simplex method is used to optimize the GC conditions.

Animals↗
PubMed2001

Determination of ketobemidone and its metabolites in plasma and urine using solid-phase extraction and liquid chromatography-mass spectrometry.

The authors developed a sensitive, specific, and rapid liquid chromatography--mass spectrometry (LC-MS) method for determining ketobemidone and its major metabolites in plasma and urine. The method involves a solid-phase extraction, high-performance liquid chromatography (HPLC), and electrospray mass spectrometry. The limit of quantification for ketobemidone and norketobemidone was 3 nmol/L. Recovery rates for ketobemidone and norketobemidone were 84.8% and 81.1%, respectively. Coefficients of variation (CV) ranged from 2.8 % to 9.5%. The method was used to determine ketobemidone and its major metabolites in clinical samples from relevant patient groups.

Analgesics, Opioid↗
PubMed2001

GC-MS determination of heroin metabolites in meconium: evaluation of four solid-phase extraction cartridges.

A procedure for extraction of heroin and metabolites for gas chromatography-mass spectrometry (GC-MS) analysis of meconium specimens that would allow detection of these analytes at low levels was needed. Solid-phase extraction (SPE) cartridges were therefore evaluated for their effectiveness in sample preparation. Four different types of commercially available extraction cartridges were used. Heroin, 6-monoacetylmorphine (6-MAM), morphine, and codeine were extracted from meconium samples using these SPE cartridges and then simultaneously analyzed using GC-MS. In each case, the extraction efficiency, linearity range, limit of detection (LOD), limit of quantitation (LOQ), between-run precision, and within-run precision were determined. Although satisfactory results were obtained with the four different types of SPE cartridges, best overall performance was observed using Clean Screen columns following the procedures outlined here. LODs as low as 20 ng/g for codeine, 10 ng/g for morphine, and 2.5 ng/g for 6-MAM were obtained, and LOQs as low as 20 ng/g for codeine, 10 ng/g for morphine, and 5 ng/g for 6-MAM were obtained. In all cases linearities were observed (r = > 0.99) for codeine, morphine, and 6-MAM over a wide concentration range (100-2000, 100-2000, and 5-100, respectively). At 50 ng/g codeine and morphine and 10 ng/g 6-MAM, the precision of analysis using these cartridges showed coefficients of variation ranging from 4.75% to 15.5%.

Codeine↗
PubMed2005

Measurement of serum salicylate levels by solid-phase extraction and desorption/ionization on silicon mass spectrometry.

The applicability of the matrix-free laser desorption/ionization on silicon mass spectrometry (DIOS-MS) to measuring serum drug levels was examined by analyzing serum salicylic acid. The optimized and simple solid-phase extraction (SPE) allowed good recovery, 88.9 +/- 5.8%, for 1.4 mM (200 mg/L) of salicylic acid in serum. The negative ion MS allowed measurements of deprotonated molecules without interference from other signals. Using a deuterium-labeled internal standard, good linearity was obtained in the 0.14 to 4.2 mM (20-600 mg/L) range, which was sufficient for monitoring the therapeutic anti-inflammatory dose. SPE followed by DIOS-MS is anticipated to be a method of measuring drug levels in blood and may allow high throughput analysis.

Humans↗
PubMed2001

Determination of sulfophenylcarboxylic acids in marine samples by solid-phase extraction then high-performance liquid chromatography.

An analytical method is presented for the determination of sulfophenylcarboxylic acids (SPC) produced by the biodegradation of linear alkylbenzene sulfonates (LAS) in marine samples. Isolation and concentration of the compounds was by solid-phase extraction. The different factors affecting extraction efficiency packing composition, pH, clean-up, ionic strength, and elution solvents--were studied and optimized. With the proposed method C4-C13SPC and C10-C13 LAS recoveries varied between 65% and 105%, with standard deviations between 0.1 and 5, respectively, for 100-mL samples and 100 microg L(-1) concentrations of each homolog. Detection limits within the range 0.5 g L(-1) (for C4SPC) to 1.0 g L(-1) (for C12SPC) were obtained by liquid chromatography with fluorescence detection. This method is the first to be proposed that enables the simultaneous determination of monocarboxylic SPC (C>3) and LAS homologs in marine samples by a simple, sensitive, and specific method giving high recoveries and reproducibility. SPC with from three to twelve carbon atoms in the carboxyl chain have been found in marine water samples.

Alkanesulfonic Acids↗
PubMed2005

Alkaline digestion and solid phase extraction method for perfluorinated compounds in mussels and oysters from South China and Japan.

Perfluorinated compounds (PFCs), such as perfluorooctane sulfonate (PFOS), have been identified in the coastal waters of China and Japan. An alkaline digestion method, coupled with solid-phase extraction (SPE), and high-performance liquid chromatography interfaced with high-resolution electrospray tandem mass spectrometry was developed to determine PFCs in mussel and oyster samples from coastal waters of South China and Japan. These techniques produced adequate recoveries and reporting limits with small quantities of PFCs. Concentrations of individual PFCs in mussels and oysters from South China and Japan ranged from 113.6 to 586.0 pg/g, wet weight (ww) for PFOS, 63.1 to 511.6 pg/g, ww for perfluorohexane sulfonate, 9.3 to 30.1 pg/g, ww for perfluorobutane sulfonate and 37.8 to 2957.0 pg/g, ww for perfluorooctane sulfonamide. The quantification of perfluorinated carboxylates was compromised by interferences from carboxylates in the procedural blanks. Perfluoroundecanoate and perfluorononanoate had relatively great blank interferences, which resulted in relatively poor limits of quantification for these compounds. Some PFCs were only identified in a limited number of samples: perfluorododecanoate in samples from Tokyo Bay, Japan (195.9 pg/g, ww); and perfluorodecanoate in Fuzhou, China (131.7 pg/g, ww) and Tokyo Bay (118.6 pg/g, ww). The greatest concentrations of perfluorooctanoate, perfluoroheptanoate, and perfluorohexanoate were observed in samples from Tokyo Bay and Bei Hai, South China.

Animals↗
PubMed1987

Liquid chromatographic analysis of alizapride and metoclopramide in human plasma and urine using solid-phase extraction.

A universal rapid, sensitive and selective high-performance liquid chromatographic method with UV detection at 230 nm has been developed for the determination of benzamide drugs in human plasma and urine. Sample pretreatment is carried out using solid-phase extraction columns, resulting in very high extraction recoveries of the compounds investigated (alizapride, metoclopramide, alpiropride, amisulpride). The detector response is linear from 25 to 10,000 ng/ml, and the detection limit is 3 ng/ml for alizapride and 10 ng/ml for metoclopramide. The proposed method is highly suitable for pharmacokinetic studies and for drug monitoring.

Anti-Arrhythmia Agents↗
PubMed2004

Liquid chromatographic method for determination of four active saponins from Panax notoginseng in rat urine using solid-phase extraction.

Four major active saponins (ginsenosides Rg1, Rb1, Rd and notoginsenoside R1) in Panax notoginseng were determined in rat urine after oral and intravenous administration of total saponins of P. notoginseng (PNS), and the urine samples were treated with solid-phase extraction (SPE) prior to liquid chromatography. A reversed-phase liquid chromatography system with ultraviolet detection and a Zorbax SB-C18 column was used. The within-day and between-day assay coefficients of variation for the four saponins in urine were less than 7% and the recovery of this method was higher than 85%. Using this method, the excretion profile of the drug in rat urine after administration of PNS was revealed for the first time.

Animals↗
PubMed2000

Determination of naphthalenesulfonates in water by on-line ion-pair solid-phase extraction and ion-pair liquid chromatography with fast-scanning fluorescence detection.

A fast analytical method for quantifying a mixture of 12 naphthalenesulfonates and naphthalenedisulfonates has been developed. This method consists of on-line ion-pair solid-phase extraction with PLRP-s sorbent and ion-pair liquid-chromatography using fast-scanning fluorescence spectrometer as a detection system and multivariate calibration. As complete separation is unnecessary, the compounds were analysed in isocratic conditions and the chromatographic analysis took only 25 min. Three-way partial least-squares (PLS) was used to carry out multivariate calibration for spiked tap water. In these conditions, quantification limits were between 0.01 and 3 microg x l(-1). Repeatability was also evaluated and relative standard deviations (n=3) were between 0.5 and 4, depending on the compound. Finally, spiked tap and Ebro river waters were analysed to evaluate prediction capability of the method.

Calibration↗
PubMed2001

Gas chromatographic-mass spectrometric determination of hydrophilic compounds in environmental water by solid-phase extraction with activated carbon fiber felt.

Simple gas chromatographic-mass spectrometric determination of hydrophilic organic compounds in environmental water was developed. A cartridge containing activated carbon fiber felt was made by way of trial and was evaluated for solid-phase extraction of the compounds in water. The hydrophilic compounds investigated were acrylamide, N,N-dimethylacetamide, N,N-dimethylformamide, 1,4-dioxane, furfural, furfuryl alcohol, N-nitrosodiethylamine and N-nitrosodimethylamine. Overall recoveries were good (80-100%) from groundwater and river water. The relative standard deviations ranged from 4.5 to 16% for the target compounds. The minimum detectable concentrations were 0.02 to 0.03 microg/l. This method was successfully applied to several river water samples.

Carbon↗
PubMed1989

Solid-phase extraction and high-performance liquid chromatographic determination of flumequine and oxolinic acid in salmon plasma.

Two methods for determination of oxolinic acid and flumequine in salmon plasma are described. The first method applies sample pretreatment on C2 disposable solid-phase extraction columns. The second method is based on direct plasma injection and on-line sample clean-up on a polystyrene-divinylbenzene precolumn. After column-switching, the analytes are separated on a polystyrene-divinylbenzene analytical column and detected with a fluorescence detector. Validation of the methods showed good sensitivity, precision and reproducibility. Both methods are well suited for determination of plasma levels of the drugs in pharmacokinetic studies in Atlantic salmon.

Animals↗
PubMed1998

Determination of phenethylamine, a phenethyl isothiocyanate marker, in dog plasma using solid-phase extraction and gas chromatography-mass spectrometry with chemical ionization.

Phenethyl isothiocyanate is unstable in aqueous media and at low pH, and rapidly degrades to phenethylamine. Concentrations of phenethylamine, a phenethyl isothiocyanate marker, in dog plasma, were determined utilizing solid-phase extraction and gas chromatography-mass spectrometry with chemical ionization using acetone as the reagent gas. Deuterated d5-amphetamine was used as an internal standard. After extraction, phenethylamine and d5-amphetamine were derivatized using MBHFBA. Ions monitored for d5-amphetamine were m/z 337 and 338; and for phenethylamine were m/z 318 and 319. Precision and accuracy were studied using control solutions prepared in naive dog plasma (80 and 300 ng/ml). Intra-day variability was determined using six replicates of each control solution analyzed on a single day. The relative standard deviation for the 80 ng/ml control was 12.9% and for the 300 ng/ml it was 12.1%. Relative accuracy was 10.9% for the low control and -4.1% for the high control. Inter-day variability was determined over a 6-day period. For the 80 and 300 ng/ml control solutions, the relative standard deviations were 15.8 and 9.1%, respectively, and relative accuracy values were 10.1 and -5.2%, respectively. Standard curves were prepared in naive dog plasma and were linear over the range of phenethylamine assayed (10-500 ng/ml). The results of this study indicate that the proposed method is simple, precise, accurate and sensitive enough for analysis of large numbers of plasma samples.

Animals↗