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PubMedDate not supplied

Solid-phase extraction cleanup for ivermectin in liver tissue.

Extraction of liver tissue with organic solvent produces coextractants with compounds of interest. The solid-phase extraction (SPE) cleanup of liver tissue developed for ivermectin removes nonpolar coextractants. Liver extract that has been reduced to dryness is reconstituted in 0.5 mL acetonitrile. The mixture is passed through 0.1 g C18 SPE column, and the eluate is collected. The column is eluted further with 2 mL acetonitrile. Combined eluates are derivatized with 1-methylimidazole and trifluoroacetic anhydride, and the ivermectin derivative is determined by liquid chromatography with fluorescence detection.

Animals↗
PubMed2003

Determination of neonicotinoid pesticide residues in vegetables and fruits with solid phase extraction and liquid chromatography mass spectrometry.

A rapid and simple extraction method for the simultaneous analysis of five neonicotinoid insecticides has been developed. Twelve different fruit and vegetable matrixes were extracted with methanol and cleaned up using a graphitized carbon solid phase extraction cartridge loading with a 20% methanol solution. The concentrated eluate after methanol elution was then analyzed for pesticide residues by liquid chromatography/mass spectrometry in the APCI positive mode. The five pesticides including nitenpyram, thiamethoxam, imidacloprid, acetamiprid, and thiacloprid were recovered at 70-95% at spike levels of 0.1 and 1 mg/kg in bell pepper, cucumber, eggplant, grape, grapefruit, Japanese radish, peach, pear, potato, rice, and tomato. Relative standard deviations were less than 10% for all of the recovery tests. The proposed method is fast, easy to perform, and could be utilized for regular monitoring of pesticide residues.

Chromatography, Gas↗
PubMed1991

Application of the Empore solid-phase extraction membrane to the isolation of drugs from blood. I. Amiodarone and desethylamiodarone.

We describe the use of a new form of solid-phase material, the Empore solid-phase extraction membrane (SPEM), for therapeutic drug monitoring. We evaluated the new extraction procedure with the companion high-performance liquid chromatographic (HPLC) method for the antiarrhythmic drug amiodarone and its metabolite, desethylamiodarone, in patients' serum. Acidified serum (250 microliters) was passed through an octyl (C8) SPEM secured in an MF-1 microfilter unit. Serum proteins and potential interferences were removed with an acetonitrile:water wash, and the retained drugs eluted with HPLC mobile phase. This eluate was injected directly onto the analytical column. Both drugs averaged 85% recovery with a linear response from a lower limit of detection at 0.05 mg/L up to 6 mg/L, and between-run precision coefficients of variation ranging from 3.1 to 6.4% over the concentration range of 0.5-3.0 mg/L. We observed significant advantages of the novel SPEM over conventional liquid-liquid or large-particle size solid-phase sorbents packed in cartridges. Minimal amounts of solvents were required, elution volume was smaller, time-consuming evaporating/concentrating steps that can influence drug stability were avoided, and little throw-away material was generated. Only the small membrane was discarded.

Amiodarone↗
PubMed1997

Management of nonmatrix interfering peaks in a chiral high-performance liquid chromatographic assay produced by solid-phase extraction of rat plasma.

PD 146923, under evaluation as an alkylating radiosensitizing drug, contains one chiral center and one chemically reactive aziridine ring. A method was developed to evaluate possible in vivo enantiomeric inversion of PD 146923 in rat plasma. Normal-phase chiral HPLC was necessary to separate the enantiomers, but a typical aqueous-based solid-phase extraction (SPE) was needed to isolate the analytes from plasma. SPE at higher analyte concentrations removed all interfering peaks and gave acceptable recoveries. However, peaks (A-G) from seven new components interfering with analyte detection at lower concentrations were produced by SPE. The interfering peaks overlapped each other, so some were not observed until other, more intense interfering peaks had been managed. The low separation efficiency of the chiral column precluded management of interfering peaks by modifying chromatographic parameters. Chemical reactivity of the analytes forced the use of mild conditions for management of interfering peaks. Peaks A-F were: (A) water from the SPE cartridge; (B) SPE sorbent endcapping; (C, E and F) nonvolatile salts of the SPE elution acid reacting with bases from the injection solvent or with unidentified bases from the SPE cartridge; (D and G) analyte degradation products. This study identifies the nonmatrix peaks coeluting with the analytes, and describes how an aqueous-based SPE method was developed for isolating these very polar, highly reactive analytes in plasma for separation in a normal-phase chiral HPLC assay. Additionally, B, C, E or F probably are present in many other solid-phase extractions, but are not observed because of polarity or solubility properties.

Acetic Acid↗
PubMed2003

Quantitative determination of sotolon, maltol and free furaneol in wine by solid-phase extraction and gas chromatography-ion-trap mass spectrometry.

A method for the analytical determination of sotolon [4,5-dimethyl-3-hydroxy-2(5H)-furanone], maltol [3-hydroxy-2-methyl-4H-pyran-4-one] and free furaneol [2,5-dimethyl-4-hydroxy-3(2H)-furanone] in wine has been developed. The analytes are extracted from 50 ml of wine in a solid-phase extraction cartridge filled with 800 mg of LiChrolut EN resins. Interferences are removed with 15 ml of a pentane-dichloromethane (20:1) solution, and analytes are recovered with 6 ml of dichloromethane. The extract is concentrated up to 0.1 ml and analyzed by GC-ion trap MS. Maltol and sotolon were determined by selected ion storage of ions in the m/z ranges 120-153 and 79-95, using the ions m/z 126 and 83 for quantitation, respectively. Furaneol was determined by non-resonant fragmentation of the m/z 128 mother ion and subsequent analysis of the m/z 81 ion. The detection limits of the method are in all cases between 0.5 and 1 microg l(-1), well below the olfactory thresholds of the compounds. The precision of the method is in the 4-5% range for levels in wine around 20 microg l(-1). Linearity holds at least up to 400 microg l(-1), and is satisfactory in all cases. The recoveries of maltol and sotolon are constant (70 and 64%, respectively) and do not depend on the type of wine. On the contrary, in the case of furaneol, red wines show constant and high recoveries (97%), while the recoveries on white wines range between 30 and 80%. Different experiments showed that this behavior is probably due to the existence of complexes formed between furaneol and sulphur dioxide or catechols. Sensory experiments confirmed that the complexed forms found in white wines are not perceived by orthonasal olfaction, and that the furaneol determined by the method can be considered as the free and odor-active fraction.

Furans↗
PubMed1994

A sensitive radioimmunoassay, combined with solid-phase extraction, for the sub-nanogram per ml determination of ondansetron in human plasma.

The development of a radioimmunoassay, incorporating solid-phase sample extraction, suitable for the subnanogram per ml determination of ondansetron base in human plasma is described. The antiserum was raised in Soay sheep following primary and booster immunizations with an immunogen prepared by conjugating 9-(carboxypropyl)-ondansetron to bovine thyroglobulin. The radioligand consisted of ondansetron specifically tritium-labelled on the N-methyl group of the indole moiety. The solid-phase extraction method, using a cyanopropyl sorbent, was introduced to remove cross-reacting metabolites and to enhance assay sensitivity. The calibration range is 0.05-2.40 ng ml-1 using a 1 ml sample of human plasma; inter- and intra-assay bias and precision are < +/- 13% and < 10% over this concentration range, respectively. The assay drift, measured as the difference in concentration values for quality control samples assayed immediately before and after the sequence of test plasma samples, is < +/- 10% for run sizes of up to 54 samples.

Animals↗
PubMed2000

Characterization of photodegradation products of alachlor in water by on-line solid-phase extraction liquid chromatography combined with tandem mass spectrometry and orthogonal-acceleration time-of-flight mass spectrometry.

On-line solid-phase extraction liquid chromatography in combination with mass spectrometry (MS), i.e. MS/MS and orthogonal-acceleration time-of-flight MS, was used for the characterization of photodegradation products of alachlor in river water. Various MS/MS scan functions were used, in particular the precursor-ion and the daughter-ion modes, to screen for degradation products with structures closely related to that of alachlor and to obtain information on characteristic fragments of the degradation products. Elemental compositions of compounds found and some of their fragments were calculated from the accurate mass information obtained with orthogonal-acceleration time-of-flight MS. Some ten degradation products could be characterized by combining various types of mass spectral information. Since quite a number of isomers were identified, structures of the degradation products were proposed by considering the most likely fragmentation patterns in MS/MS experiments. Degradation products of alachlor found in the current study were compared with those reported in the literature.

Acetamides↗
PubMed1994

Simultaneous determination of primidone and its active metabolites in rat plasma by high-performance liquid chromatography using a solid-phase extraction technique.

Primidone (PRM) and its active metabolites, phenylethylmalonamide (PEMA) and phenobarbital (PB), in rat plasma were simultaneously determined using a solid-phase extraction technique followed by high-performance liquid chromatography (HPLC). Twenty microliters of plasma was applied to a Bond-Elut C-18 cartridge column with 0.1 microgram of acetanilide (internal standard, IS). After the column was washed, PRM, PEMA, PB, and IS were eluted with methanol and injected into the HPLC system. Calibrations for these substances were linear in the range of 0-20 micrograms/mL. The coefficients of variation were 1.5-7.9% and 3.4-9.1% in the within-day and between-day assays, respectively. The recovery rates were 96.8-101.8%. The pharmacokinetics of these substances were examined after oral administration of PRM (50 mg/kg) to rats. The Tmax values for PRM, PEMA, and PB were 1.4, 5.7, and 6.6 h, respectively, and the Cmax values were 18.2, 8.1, and 9.6 micrograms/mL, respectively. This method is useful for pharmacokinetic studies of PRM and its active metabolites.

Administration, Oral↗
PubMed2003

Simultaneous quantitation of enalapril and enalaprilat in human plasma by 96-well solid-phase extraction and liquid chromatography/tandem mass spectrometry.

A sensitive and rapid method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) combined with rapid solid-phase extraction (SPE) has been developed and validated for the quantitative determination of enalapril and its active metabolite enalaprilat in human plasma. After addition of internal standard to human plasma, samples were extracted by 96-well SPE cartridge. The extracts were analyzed by HPLC with the detection of the analyte in the multiple reaction monitoring (MRM) mode. This method for the simultaneous determination of enalapril and enalaprilat was accurate and reproducible, with respective limits of quantitation of 0.2 and 1.0 ng/mL in plasma. The standard calibration curves for both enalapril and enalaprilat were linear (r(2) = 0.9978 and 0.9998) over the concentration ranges 0.2-200 and 1.0-100 ng/mL in human plasma, respectively. The intra- and inter-day precision over the concentration range for enalapril and enalaprilat were lower than 13.3 and 15.4% (relative standard deviation, %RSD), and accuracy was between 89.2-105.0 and 91.9-104.7%, respectively.

Calibration↗
PubMed2000

Automated solid-phase extraction and two-step derivatisation for simultaneous analysis of basic illicit drugs in serum by GC/MS.

A combination of automated solid-phase extraction (SPE) and subsequent two-step derivatisation has been developed for the simultaneous analysis of basic drugs of abuse and cocaine metabolites in serum samples. Substances included in this procedure are morphine, codeine, methadone, cocaine, benzoylecgonine, methylecgonine, amphetamine, methamphetamine, MDMA, MDEA and MDA. SPE with mixed-mode cartridges (RP-C8 and cation-exchange) was fully automated with a Zymark RapidTrace SPE robot. GC/MS analysis was performed after derivatisation with a new two-step reaction by trifluoroacetic anhydride and 2,2,3,3,3-pentafluoropropanol. High recoveries (> 85%) with high reproducibility (CV 1.1-3.8%) were found for all drugs. High correlation coefficients (r > 0.998) were obtained due to the addition of deuterated standards prior to extraction. Experience obtained over 2 years of applying this method to drug analysis in serum is discussed.

Automation↗
PubMed1995

Solid-phase extraction on Styrosorb cartridges as a sample pretreatment method in the stereoselective analysis of propranolol in human serum.

Sample pretreatment using solid-phase extraction (SPE) on cartridges filled with small-particle Styrosorb porous polystyrene-based sorbent has been used in the analysis of propranolol enantiomers in human serum by high-performance liquid chromatography (HPLC) with fluorescent detection. SPE on Sep-Pak C18 cartridges was used as a reference pretreatment method. The propranolol content of the samples was determined by achiral normal-phase HPLC and the enantiomeric ratio of propranolol (S/R) was then determined by chiral HPLC on a column with silica-bonded cellulose-tris(3,5-dimethylphenyl carbamate). Recoveries of propranolol from serum using SPE on Styrosorb and C18 phases were 97 +/- 5% and 96 +/- 5%, respectively. Detection and quantification limits for propranolol enantiomers were 4 and 7 ng/ml, respectively.

Chromatography, High Pressure Liquid↗
PubMed1989

The use of graphitized carbon black in solid phase extraction: comparison with C18 bonded silica gel.

Preliminary studies on the properties of a commercially available graphitized carbon black for the solid-phase (or liquid-solid) extraction of drugs and metabolites from biological fluids such as urine and plasma are described. A variety of basic drugs, all of the beta-blocker type, were efficiently extracted from dog plasma and subsequently recovered from the adsorbent using chloroform-methanol mixtures. Similarly metabolites of the non-steroidal anti-flammatory drug ibuprofen also were efficiently extracted from human urine. The proportions of methanol and chloroform used for elution were found to be critical to ensure complete recoveries of adsorbed material. Proton NMR studies of the column eluates from both carbon and C18 bonded silica gel extraction cartridges revealed differences in capacity and selectivity following the application of ibuprofen containing metabolite samples.

Adrenergic beta-Antagonists↗
PubMed2005

Solid phase extraction of some precious metals from hydrochloric acid to polystyrene-divinylbenzene porous resin impregnated with polyoxyethylene-type nonionic surfactant.

The solid phase extraction of gold(III), platinum(II), and palladium(II) to surfactant-impregnated polystyrene-divinylbenzene porous resin (XAD-4) was studied. The extracting media could be prepared just by mixing the resin in aqueous surfactant solutions. XAD-4 impregnated with a nonionic surfactant, polyethylene glycol monooleyl ether, was useful for extracting gold(III) from hydrochloric acid. The extractions of platinum(II) and palladium(II) were improved in the use of XAD-4 impregnated with a nitrogen-containing nonionic surfactant, polyethylene glycol stearyl amine. On the other hand, base metals such as copper(II), cobalt(II), nickel(II) and zinc(II), were hardly extracted.

Chemistry Techniques, Analytical↗
PubMed2004

Analysis of human urine for fifteen phthalate metabolites using automated solid-phase extraction.

We improved our previous analytical method to measure phthalate metabolites in urine as biomarkers for phthalate exposure by automating the solid-phase extraction (SPE) procedure and expanding the analytical capability to quantify four additional metabolites: phthalic acid, mono-3-carboxypropyl phthalate, mono-isobutyl phthalate (miBP), and monomethyl isophthalate. The method, which involves automated SPE followed by isotope dilution-high performance liquid chromatography (HPLC)-electrospray ionization (ESI)-tandem mass spectrometry (MS), allows for the quantitative measurement of 15 phthalate metabolites in urine with detection limits in the low ng/ml range. SPE automation allowed for the unattended sequential extraction of up to 100 samples at a time, and resulted in an increased sample throughput, lower solvent use, and better reproducibility than the manual SPE. Furthermore, the modified method permitted for the first time, the separation and quantification of mono-n-butyl phthalate (mBP) and its structural isomer miBP. The method was validated on spiked pooled urine samples and on pooled urine samples from persons with no known exposure to phthalates.

Automation↗
PubMed2000

Solid-phase extraction and high-performance liquid chromatographic separation of pigments of red wines.

The adsorption and desorption capacities of 11 different solid-phase extraction sorbents were tested for the preconcenration of pigments of various Hungarian red wines. The concentrates were evaluated by multiwavelengh spectrophotometry combined with a spectral mapping technique (SPM) and by reversed-phase high-performance liquid chromatography. The highest (10-fold) concentration of pigments was achieved on octadecylsilica sorbent. It can be used five times without losing adsorption and desorption characteristics. SPM indicated that multiwavelength spectrophotometry can be employed for the differentiation of red wines. Comparison of the chromatograms of pigments with and without preconcentration showed that preconcentration makes possible the separation and detection of pigments present in low concentration in red wines.

Chromatography, High Pressure Liquid↗
PubMed2001

Solid-phase extraction with styrene-divinylbenzene sorbent for high-performance liquid or gas chromatographic determination of urinary chloro- and methylthiotriazines.

A solid-phase extraction (SPE) procedure on a styrene-divinylbenzene (SDB-1 cartridge) for extraction and cleaning of the triazine herbicides atrazine, simazine, ametryn, and prometryn and atrazine monodealkylated metabolites from urine samples was developed and optimised for final high-performance liquid chromatographic (HPLC-UV diode array detection) and gas chromatographic (GC-electron-capture detection and GC-thermionic-sensitive detection) analyses. Interfering polar matrices were eliminated by rinsing SDB-1 with 1% acetonitrile in water or with pure water. Extraction recoveries were from 78 to 101% with an RSD of about 10% for all studied compounds. The extraction recovery for the didealkylated atrazine metabolite was significantly lower and this compound cannot be determined with these procedures. Sorbent matrix generated interferences, although not detected by the chromatographic system, lowered the response of nitrogen-phosphorus and electron-capture GC detectors for monodealkylated chlorotriazines when compared to standards prepared in n-hexane. HPLC and GC analysis with SPE (SDB-1) preconcentration showed excellent linearity over the concentration range tested, with detection limits in urine of 10 ng ml(-1) for the parent herbicides (HPLC and GC analysis) and 20 ng ml(-1) for monodealkylated chlorotriazines (HPLC analysis).

Chromatography, Gas↗
PubMed2001

Dialysis-solid-phase extraction combined on-line with non-aqueous capillary electrophoresis for improved detectability of tricyclic antidepressants in biological samples.

Dialysis-solid-phase extraction (SPE) sample pretreatment is combined on-line with non-aqueous capillary electrophoresis for the determination of tricyclic antidepressants in urine and serum. After clean-up and enrichment, the water is removed from the sample matrix and the analytes are eluted from the cartridge by means of an organic solvent. Next, the eluate is transported to the capillary and the injection is performed electrokinetically. This injection, which does not suffer from an adverse sample matrix effect because of the SPE step, results in further analyte concentration. The detection limits are in the 0.02-0.1 microg/ml range and the day-to-day repeatabilities are between 2.5 and 9.5%, which is quite satisfactory.

Antidepressive Agents, Tricyclic↗
PubMed1998

Automated on-line solid-phase extraction and high-performance liquid chromatographic analysis of total and free pyridinium crosslinks in serum.

An automated on-line solid-phase extraction procedure for free and total pyridinium crosslinks in serum, with HPLC analysis, is described. The pyridinium crosslinks either following hydrolysis in 3 M HCl or free in neat serum were extracted using a Gilson Aspec XLi system onto extraction cartridges containing an octylsilane/cation exchanger sorbent. Up to 525 microliters of serum could be loaded onto the extraction cartridges. After washing, the crosslinks were eluted with 400 microliters of 100 mM sodium formate pH 5 and 380 microliters of this was concentrated on a RPB guard column eluted with 100 mM HFBA. The crosslinks were backflushed and separated on a 5-micron ODS analytical column eluted with 30 mM HFBA with 18% MeCN at 1 ml/min and detected by their native fluorescence (excitation 295 nm, emission 400 nm). The use of a high sensitivity fluorescence detector was essential. Recoveries were 95-100% with a limit of detection (S/N = 2) of 109 pmol/l (pM) for pyridinoline (Pyr) and 143 pM for deoxypyridinoline (dPyr). The inter-assay R.S.D. was 9% for pyridinoline and 10.8% for deoxypyridinoline. The throughput of the system was up to 50 samples per day.

Amino Acids↗