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PubMed2001

[Sorbents for solid phase extraction and their use].

Extraction on the solid phase is a rapid, simple, effective, and flexible method of preparation of samples for the analysis proper and it can be used in many areas of analysis (pharmacy, biochemistry, food industry, environmental examination, etc.). Possible use in on-line and automatic systems is also advantageous. A very wide scale of proposed sorbents and the use of their combinations thus make extraction on the solid phase an effective method for the isolation and preconcentration of the analyte from the complex matrix of the sample.

Absorption↗
PubMed2005

Confirmatory and quantitative analysis of beta-lactam antibiotics in bovine kidney tissue by dispersive solid-phase extraction and liquid chromatography-tandem mass spectrometry.

A simple, rapid, rugged, sensitive, and specific method for the confirmation and quantitation of 10 beta-lactam antibiotics in fortified and incurred bovine kidney tissue has been developed. The method uses a simple solvent extraction, dispersive solid-phase extraction (dispersive-SPE) cleanup, and liquid chromatography-tandem mass spectrometry (LC/MS/MS) for confirmation and quantitation. Dispersive-SPE greatly simplifies and accelerates sample cleanup and improves overall recoveries compared with conventional SPE cleanup. The beta-lactam antibiotics tested were as follows: deacetylcephapirin (an antimicrobial metabolite of cephapirin), amoxicillin, desfuroylceftiofur cysteine disulfide (DCCD, an antimicrobial metabolite of ceftiofur), ampicillin, cefazolin, penicillin G, oxacillin, cloxacillin, naficillin, and dicloxacillin. Average recoveries of fortified samples were 70% or better for all beta-lactams except DCCD, which had an average recovery of 58%. The LC/MS/MS method was able to demonstrate quantitative recoveries at established tolerance levels and provide confirmatory data for unambiguous analyte identification. The method was also tested on 30 incurred bovine kidney samples obtained from the USDA Food Safety and Inspection Service, which had previously tested the samples using the approved semiquantitative microbial assay. The results from the quantitative LC/MS/MS analysis were in general agreement with the microbial assay for 23 samples although the LC/MS/MS method was superior in that it could specifically identify which beta-lactam was present and quantitate its concentration, whereas the microbial assay could only identify the type of beta-lactam present and report a concentration with respect to the microbial inhibition of a penicillin G standard. In addition, for 6 of the 23 samples, LC/MS/MS analysis detected a penicillin and a cephalosporin beta-lactam, whereas the microbial assay detected only a penicillin beta-lactam. For samples that do not fall into the "general agreement" category, the most serious discrepancy involves two samples where the LC/MS/MS method detected a violative level of a cephalosporin beta-lactam (deacetylcephapirin) in the first sample and a possibly violative level of desfuroylceftiofur in the second, whereas the microbial assay identified the two samples as having only violative levels of a penicillin beta-lactam.

Animals↗
PubMed1998

Quantitation of psilocin in human plasma by high-performance liquid chromatography and electrochemical detection: comparison of liquid-liquid extraction with automated on-line solid-phase extraction.

Two modifications of the HPLC-ED method with respect to extraction procedure used have been developed for psilocin, the active metabolite of psilocybin, in human plasma using either liquid-liquid extraction (LLE) or automated on-line solid-phase extraction (on-line SPE). Each type of the sample preparation required a different HPLC system followed by electrochemical detection at 650 to 675 mV. The limit of quantitation of both modifications was 10 ng/ml psilocin. There was no significant difference observable between the LLE and the on-line SPE in terms of method standard deviation (LLE 1.82%, on-line SPE 1.13%) and the analytical results. However, the advantages of on-line SPE in addition to different selectivity were less manual effort, smaller plasma volumes of 400 microl (LLE 2 ml) and a recovery of psilocin in human plasma of nearly 100% (LLE 88%). In contrast to a previous procedure both methods were rapid, simple and reliable and yielded high plasma recoveries. They were used successfully in the quantitation of psilocin in plasma samples obtained from healthy volunteers after p.o. administration of 0.2 mg psilocybin per kg body mass. Plasma concentration curves and pharmacokinetic parameters were calculated.

Administration, Oral↗
PubMed2006

Rapid gas chromatography/mass spectrometry quinine determination in plasma after automated solid-phase extraction.

The combined use of an automatic solid-phase extraction (SPE) apparatus with Oasis MCX cartridges and gas chromatography/mass spectrometry (GC/MS) to rapidly quantify quinine in biological samples with cyproheptadine as the internal standard is described. The selected ion monitoring mode, with the quantification ions m/z 136 and 287 (qualifier ions: m/z 261, 381 and 215, 96), allows the estimation of quinine levels, respectively. Separation was completed within 12.7 min. Excellent linearity was found up to 10 000 microg/L of plasma. The limit of detection (LOD) was 12.2 microg/L and the limit of quantification (LOQ) was 40.6 microg/L. High reproducibility (intra-assay CV range 1.9-4.3%, inter-assay CV range 2.2-11.3%) and accuracy values (intra-assay range 83.2-103.7%, inter-assay range 86.8-103.7%) were obtained. Recoveries were concentration-independent (97.2% and 89.8% for 4000 and 10 000 microg/L, respectively). This sensitive, simple assay for quinine in various matrices meets the current requirements for bioanalytical assays and may be used to monitor quinine levels in patients developing severe malaria with acute renal failure during hemofiltration. The optimal quinine dose in this situation is not really established and to improve clinical care, quinine concentrations might be explored to improve efficacy and minimise potential toxicity.

Gas Chromatography-Mass Spectrometry↗
PubMed2001

Simultaneous determination of sixteen phenylurea herbicides in water by high performance liquid chromatography and solid phase extraction.

A high performance liquid chromatography (HPLC) procedure for simultaneous determination of sixteen phenylurea herbicides in water is described. A Lichrospher 100 RP-18e column and spectrophotometric detection at 240 nm were used. Adequate retention was achieved with a mobile phase of acetonitrile/water solution with gradient elution. The HPLC analysis time was less than 20 min. The herbicides were isolated from water samples by using a single solid phase extraction procedure with C18 solid-phase columns. An enrichment factor of 1,000 was achieved. Recoveries were in the range between 87.8% and 103.7%. The detection limits of the whole procedure achieved were less than one-tenth of the maximum limit permitted by the European Community standard for drinking water.

Chromatography, Gas↗
PubMed2003

Isolation of chlorinated fatty acid methyl esters derived from cell-culture medium and from fish lipids by using an aminopropyl solid-phase extraction column.

An aminopropyl-based solid-phase extraction technique was used for isolation of chlorinated fatty acids in lipids. A range of different chlorinated fatty acids was eluted in a small volume of solvent (4 ml) and the recoveries of the different species and isomers were quantitative. Only 1% of the vastly dominating unchlorinated fatty acid methyl esters were recovered in the fractions containing the chlorinated fatty acid methyl esters. This method makes it possible to isolate and detect > or = 1 microg of a chlorinated fatty acid methyl ester in 1 g of lipid.

Animals↗
PubMed1999

Rapid preconcentration method for the determination of azadirachtin-A and -B, nimbin and salannin in neem oil samples by using graphitised carbon solid phase extraction.

A simple and rapid method involving solid phase extraction and liquid chromatography for the determination of azadirachtin-A and -B, nimbin and salannin at nanogram levels in neem oil samples is presented. The neem oil samples are defatted and the compounds of interest extracted by mixing the sample with hexane and passing the hexane solution through a graphitised carbon black column. After washing the column with 2 ml of hexane, azadirachtin-A and -B, nimbin and salannin are eluted with 5 ml of acetonitrile and quantified using HPLC with UV detection. The recoveries of azadirachtin-A and -B, nimbin and salannin in fortified oil samples were 97.4-104.7%. The upper limit of quantification is up to 100 micrograms ml-1 without any additional clean-up and with little interference from lipids during the analysis by HPLC. The method was successfully applied to various neem oil samples collected from different locations in India.

Antiviral Agents↗
PubMed2004

[Monitoring of the residue of fosthiazate in water samples using solid-phase extraction coupled with gas chromatography/mass spectrometry].

Solid-phase extraction (SPE) coupled with gas chromatography/mass spectrometry (GC/MS) was used to determine the fosthiazate residue in water samples. The water samples were first filtered through cellulose filters (0.45 microm pore size). A 100 mL volume of filtered water, in which 1 mL of methanol has been added, was then passed through a pre-conditioned 3 cm C18 cartridge at a flow-rate of 1.5 mL/min. Elution was performed by 1 mL of methanol. The eluant was finally dried under reduced pressure for solvent evaporation. The volume was quantitatively adjusted to 0.5 mL with methanol. The analysis was carried out on GC/MS. The mass spectrometer was operated in selected ion monitoring (SIM) mode. According to mass spectrum of fosthiazate, three selected ions at m/z of 126, 195, 283, respectively, were monitored for identification and quantification. High sensitivity and selectivity were achieved by using this method. The limit of detection for fosthiazate in water samples was determined to be 56.4 ng/L. The linearity was demonstrated over a wide range of concentrations covering from 0.282 to 141 microg/L. The recoveries were more than 85.5% and the relative standard deviations for the overall procedure were less than 4.42%. The fosthiazate residue was detected in the water samples from a pool near cropland where fosthiazate was used. The results demonstrate the suitability of the SPE-GC/MS approach for the analysis of fosthiazate in water.

Gas Chromatography-Mass Spectrometry↗
PubMed2005

Quantification of free and total salicylic acid in plants by solid-phase extraction and isocratic high-performance anion-exchange chromatography.

Salicylic acid (SA) is an important signaling compound in plants and is involved in various defense responses. Here we report a new method for quantification of free and total soluble SA in Arabidopsis thaliana with 5-fluorosalicylic acid (5-FSA) as internal standard. The SA was isolated from leaf extracts by solid-phase extraction with phenyl-phase cartridges and selectively eluted as the cationic iron(III)-complex. Recoveries of SA and 5-FSA were equal and exceeded 90%. Free SA was subsequently released from the iron(III)-complex by addition of 2,2'-bipyridyl and high-performance anion-exchange chromatography was performed on an NH2 column. The SA appeared as last peak with a retention time of 15 min, baseline-separated from other substances. On-line detection was performed fluorimetrically for both SA and 5-FSA at an excitation wavelength of 300 nm and an emission wavelength of 410 nm, because both substances give similar fluorescence spectra. The detection limit for SA was 5 ng g(-1) FW for a sample size of 100 mg. Thus the main advantages of the method are highly selective sample preparation, increased sensitivity, reduced analysis time compared with reversed-phase HPLC, and use of a novel internal standard detectable under the same conditions as SA. The techniques described are applicable to other plant materials.

Arabidopsis↗
PubMedDate not supplied

Use of solid-phase extraction systems to improve the sensitivity of Artemia bioassays for trichothecene mycotoxins.

Solid-phase extraction was used to preconcentrate trichothecene mycotoxins from rivers and streams in order to develop and improve a rapid and sensitive bioassay using the brine shrimp Artemia salina. For T-2 toxin, HT-2 toxin, and 4,15-diacetoxyscirpenol, LC50 values obtained were 172, 600, and 700 micrograms/L, respectively. The LC50 for 4-deoxynivalenol was 21 mg/L. A more than 5-fold increase in sensitivity was observed when solid-phase extraction (SPE) was used in conjunction with the Artemia bioassay. For T-2 toxin, HT-2 toxin, and 4,15-diacetoxyscirpenol, LC50/SPE values after solid-phase extraction were 21, 83, and 130 micrograms/L. The use of river and stream waters and chlorinated water did not seem to interfere with the bioassay.

Animals↗
PubMed1999

HPLC assay of Lidocaine in plasma with solid phase extraction and UV detection.

A sensitive and reliable method based on solid-phase extraction and reversed-phase liquid chromatography was developed and validated for the quantitation of Lidocaine (Lid) in dog plasma. Phenacemide was used as an internal standard (IS) in the extraction which employed C18 solid-phase extraction cartridges. The washing and eluting solutions were 2 ml acetonitrile-pH 9.0 phosphate buffer (10:90 v/v) and 0.5 ml acetonitrile-pH 4.0 phosphate buffer (40:60 v/v). respectively. The eluent obtained from the cartridge was directly analyzed on a reversed-phase ODS column with UV detection at 210 nm. A clean chromatogram and high sensitivity were achieved at this wavelength. The mobile phase was acetonitrile and pH 5.9 phosphate buffer (20:80 v/v). The retention times were 6.4 and 7.2 min for Lid and IS, respectively, at a flow rate of 1.0 ml min(-1). The mean absolute recovery was 96.6% (n = 9) with a CV of 3.8% for Lid and 81.7% with CV of 2.5% (n = 3) for IS. The limit of quantitation was 20 ng ml(-1), with the intra- and inter-day precisions (n = 5) of 4.4 and 3.4%, respectively, and the intra- and inter-day accuracies (n = 5) of -4.3 and -5.0%, respectively. For the analyses of Lid in spiked plasma samples at 20, 100 and 200 ng ml(-1), the overall mean intra- and inter-day precisions (n = 15) were 3.9 and 4.9%, respectively, and the overall mean intra- and inter-day accuracies (n = 15) were -3.7 and -4.6%, respectively. The correlation coefficients for calibration plots in the range 20-1000 ng ml(-1) in plasma were typically higher than 0.998. The suitability of the method was demonstrated by the study in a beagle dog receiving a low intravenous dose of Lid.

Acetonitriles↗
PubMed1998

Straightforward solid-phase extraction method for the determination of verapamil and its metabolite in plasma in a 96-well extraction plate.

Straightforward solid-phase extraction (SPE) methods were developed for the determination of verapamil and its metabolite in a plasma matrix. The spiked plasma sample was pretreated with 2% phosphoric acid followed by two different SPE methods using a Waters Oasis HLB 96-well extraction plate. Recoveries greater than 90% were obtained using both a generic and a selective SPE methods. The generic method is a good starting protocol, and it is applicable to a wide range of compounds. This generic method consists of using 5% methanol as the wash solvent, and 100% methanol for the elution. The limitation of the non-specific method is that it does not remove all plasma constituents that interfere with the quantitation of the metabolite, norverapamil. A second, more specific method was developed using the same Oasis HLB sorbent which removes more plasma interferences and provides cleaner extracts for the HPLC-UV analysis. This selective method uses both the methanol concentration and the pH advantageously to preferentially isolate the analytes of interest from a complex sample matrix. Recoveries of greater than 90% with R.S.D.s less than 3.8% were obtained with this selective method.

Animals↗
PubMed2001

Molecularly imprinted polymers: new molecular recognition materials for selective solid-phase extraction of organic compounds.

During the last few years molecularly imprinted polymers have appeared as new selective sorbents for solid-phase extraction of organic compounds in different samples. Molecular imprinting technology involves the preparation of a polymer with specific recognition sites for certain molecules. Once the polymer has been obtained, it can be used in solid-phase extraction protocols, where a careful selection of the most appropriate solvents to be used in the different steps (sample loading, washing and elution) is needed in order to extract the target analyte selectively. This review describes the state of the art of this methodology, including the preparation of imprinted polymers, a process description for molecularly imprinted solid-phase extraction, as well as more recent applications. It is concluded that molecularly imprinted solid-phase extraction is a powerful tool to selectively isolate certain analytes, and future advances are to be expected in order to widen the field of application.

Chromatography, Liquid↗
PubMed2005

Determination of fluoroquinolones in edible animal tissue samples by high performance liquid chromatography after solid phase extraction.

In the present work, a rapid, accurate, and sensitive method has been developed for the quantitative determination of five fluoroquinolones (enoxacin, ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin) in edible animal tissues (muscle tissue, liver, kidney, and eggs). The separation was accomplished on an Inertsil (250 x 4 mm) C8, 5 microm, analytical column, at ambient temperature within 15 min. The mobile phase consisted of a mixture of citric acid (0.4 mol L(-1))-CH3OH-CH3CN (87:9:4% v/v). UV detection at 275 nm yielded the following limits of detection: 100 pg per 20 microL injected volume for enoxacin, norfloxacin, and ciprofloxacin, 20 pg for ofloxacin, and 200 pg for enrofloxacin. Peaks in real samples were identified by means of a photodiode array detector. The method was validated in terms of intra-day (n = 8) and inter-day (n = 8) precision and accuracy. Tissue samples were purified from endogenous interference by solid-phase extraction using Oasis HLB cartridges. The solid-phase extraction protocol was optimized in terms of retention and elution. Recovery rates at fortification levels of 40, 60, and 80 ng/g ranged from 82.5% to 111.1%. The applicability of the method was examined using real samples from a chicken treated orally with the five studied fluoroquinolones.

Animals↗
PubMedDate not supplied

Determination of organophosphorus pesticide residues in the roots of Platycodon grandiflorum by solid-phase extraction and gas chromatography with flame photometric detection.

A simple and rapid sample preparation method using accelerated solvent extraction and solid-phase extraction (SPE) cleanup for determining organophosphorus (OP) pesticides in the roots of Platycodon grandiflorum was developed. The OP pesticides were concentrated by use of an SPE cartridge (ENVI-Carb) and quantitatively analyzed and confirmed by capillary gas chromatography with flame photometric detection. The pesticides were eluted from the cartridges with 20 mL acetonitrile-toluene (3 + 1, v/v). The average recovery from 10 g PF grandiflorum roots, fortified at 3 levels ranging from 0.04 to 1.00 mg/kg, was 91.9% with a relative standard deviation of 4.3%. The limits of detection ranged from 1.16 x 10(-3) mg/kg (dimethoate) to 4.64 x 10(-3) mg/kg (dichlorvos). The proposed method showed acceptable accuracy and precision while minimizing environmental concerns, time, and labor.

Acetonitriles↗
PubMed2001

[Simple and rapid analysis of trenbolone and zeranol residues in cattle muscle and liver by stack-cartridge solid-phase extraction and HPLC using on-line clean-up with EC and UV detection].

A simple and rapid analytical method was established for detection of anabolic agents, zeranol and alpha-trenbolone and beta-trenbolone residues in cattle muscle and liver. This method consisted of aqueous acetonitrile extraction and successive solid-phase extraction with a tandem connected octadecyl (C18)-aminopropyl (NH2) cartridge, followed by on-line clean-up using multidimensional HPLC with EC and UV detection. On-line clean-up was performed by a three-column switching technique, the first column being a Diol size exclusion column (SEC), the second, an internal surface reversed phase trapping column (TC) and the third, a C18 analytical column (AC). Sample solution from solid-phase extraction was injected into the SEC. The anabolic agents eluted from the SEC were introduced into a TC, and the anabolic agents trapped in the TC were rapidly loaded onto an analytical column after changing the eluent. Zeranol in the eluate from the analytical column was detected at 700 mV ECD and alpha- and beta-trenbolone were detected at UVD 350 nm. SEC and TC were washed and conditioned to the initial state just after the loading of the desired fraction on the AC. Recoveries from muscle fortified at a level of 0.002 mg/L (maximal residue limits, MRLs) averaged 86.1% for zeranol and 77.0% for beta-trenbolone, and recoveries from liver at a level of 0.010 mg/kg (MRLs) averaged 74.3% for zeranol and 73.1% for alpha-trenbolone. The quantitation limits for all of them were 0.001 mg/kg in muscle and 0.002 mg/kg in liver.

Anabolic Agents↗
PubMed1999

Simple high-performance liquid chromatography determination of ampicillin in human serum using solid-phase extraction disk cartridges.

A simple and reproducible method for the analysis of ampicillin in human serum was developed. Serum samples were extracted using solid-phase extraction disk cartridges containing a sorbent of styrene divinyl/benzene. Extracts were separated by reversed-phase C18 high-performance liquid chromatography with UV detection at 220 nm. The mobile phase consisted of acetonitrile-10 mM NaH2PO4 (6.5:93.5, v/v). Using this extraction procedure, recovery from serum was 98.4+/-5.6%. The quantitation limit was 0.19 microg/ml using 0.5 ml of serum. The calibration curves from 0.19 to 9.41 microg/ml were linear with correlation coefficients of 0.999. This method is suitable for therapeutic drug monitoring of ampicillin (ABPC) after oral administration of lenampicillin hydrochloride.

Ampicillin↗
PubMed1996

High performance liquid chromatographic assay of amprolium and ethopabate in chicken feed using solid-phase extraction.

A method for the assay of mixtures of amprolium and ethopabate in chicken feed was developed utilizing reversed-phase high-performance liquid chromatography (HPLC) after sample clean-up of a methanolic extract by solid-phase extraction using CN cartridges. HPLC was done with benzocaine as internal standard on a C-8 column with methanol-water 40:60, containing octanesulfonic acid, triethylamine and acetic acid, as mobile phase. Eluate was monitored at 274 nm. Baseline separation was achieved with retention times of approximately 7.5, 9.4, and 10.4 min, for amprolium, benzocaine, and ethopabate respectively. Feed constituents did not give peaks after 6.5 min. Peak area ratios were linear over 10-180 ng of amprolium, and 2-18 ng of ethopabate injected. Limits of quantitation at AUFS 0.05 were 0.5 and 0.3 ng respectively. Recovery studies from spiked feed (n = 9), covering +/- 30% of usual doses in feed, gave percent recoveries (+/- SD) of 99.4 +/- 1.4% for amprolium and 100.5 +/- 2.6% for ethopabate. Applying the method to two different batches of commercial feed gave results which were comparable to those obtained by the AOAC spectrofluorometric methods.

Amprolium↗