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PubMed1997

[Separation and detection of seven carbamate pesticides in biological samples by solid phase extraction and high performance liquid chromatography].

Methomyl, metolcarb, propoxur, carbaryl, isoprocarb, diuron and bassa are all carbamate pesticides. In this paper, a reversed-phase HPLC method is described for analysis of these carbamate pesticides in biological samples with Spherisorb C18 column (150 mm x 2.0 mm i.d., 5 microm), 60:40 (V/V) MeOH-H20 eluent and photodiode array detector. These pesticides were identified by their spectrum characteristics and retention times. Their quantity was determined by their peak area. The biological samples were extracted with C18 cartridge and eluted with ethyl acetate, and then analysed by HPLC. The sensitivity of detection for the seven carbamates was in the range of 1-2 mg/L of blood sample and 5-10 mg/L of urine sample. The recoveries of blood and urine samples were 70%-80% and 65%-82%, respectively. The method is simple, rapid and highly sensitive.

Carbamates↗
PubMed2006

High-throughput screening for multi-class veterinary drug residues in animal muscle using liquid chromatography/tandem mass spectrometry with on-line solid-phase extraction.

A rapid qualitative method using on-line column-switching liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed and validated for screening 13 target veterinary drugs: four macrolides - erythromycin A, josamycin (leucomycin A3), kitasamycin (leucomycin A5), and tylosin A; six (fluoro)quinolones - ciprofloxacin, danofloxacin, enrofloxacin, flumequine, oxolinic acid, and sarafloxacin; and lincomycin, virginiamycin M1, and trimethoprim in different animal muscles. Clindamycin, norfloxacin, nalidixic acid, oleandomycin, ormetoprim, and roxithromycin were used as the internal standards. After simple deproteination and analyte extraction of muscle samples using acetonitrile, the supernatant was subjected to on-line cleanup and direct analysis by LC/MS/MS. On-line cleanup with an extraction cartridge packed with hydrophilic-hydrophobic polymer sorbent followed by fast LC using a short C18 column resulted in a total analysis cycle of 6 min for 19 drugs. This screening method considerably reduced the time and the cost for the quantitative and confirmatory analyses. The application of a control point approach was also introduced and explained.

Animals↗
PubMed2003

Determination of pyronaridine in whole blood by automated solid phase extraction and high-performance liquid chromatography.

A new extraction procedure for the analysis of pyronaridine in whole blood is presented. A weak cation exchanger with a carboxylic acid (CBA) sorbent was found to be a suitable solid phase sorbent for the extraction of pyronaridine. High-performance liquid chromatography with UV detection at 278 nm and an electrochemical detector at +0.75 V is used. The electrochemical detector gives higher selectivity than the UV detector. The separation was performed using a C18 reversed phase column with mobile phase of acetonitrile-phosphate buffer (0.01 mol/L, pH 2.5)- sodium perchlorate (1.0 mol/L; 22:77:1, v/v/v). The within-day RSDs were below 5% at all concentration levels between 75 nmol/L and 1500 nmol/L, and the between-day RSDs were below 14% at all concentration levels. The limit of quantification was about 50 nmol/L in 1000 microL whole blood with an RSD of 20% or less on a day-to-day basis. The stability of pyronaridine is increased if the pH is less than 3 in water solutions. In whole blood, the concentration decreases by about 10% for each freeze-thaw cycle performed. At room temperature (about 22 degrees C), pyronaridine concentration in whole blood decreases by about 10% within 12 to 24 hours.

Chromatography, High Pressure Liquid↗
PubMed2006

Determination of amphetamines in human urine by liquid chromatography with fluorimetric detection using a solid-phase extraction procedure.

A precise and feasible HPLC method has been developed for the analysis of amphetamine (AMPH), methamphetamine (MAMPH) and methylenedioxymethamphetamine (MDMA, ecstasy) in human urine. A chromatographic run on a C8 Genesis (150 mm x 4.6 mm, 5 microm) column maintained at 30 degrees C lasts about 17 min, using a mobile phase composed of ACN (12%) and a pH 2.5 phosphate buffer (88%) containing 0.3% triethylamine. Mirtazapine was used as the internal standard. Good linearity was found in the 100-2000 ng/mL concentration range for AMPH and MAMPH and in the 12-2000 ng/mL concentration range for MDMA. The pretreatment of urine samples was carried out by means of a careful SPE procedure on C2 cartridges. The extraction yields were very satisfactory for all analytes, with average values greater than 97%. The leading conditions allowed the determination of AMPH, MAMPH and MDMA with satisfactory precision and accuracy. The method has been successfully applied to the determination of the analytes in urine of AMPH users.

Amphetamines↗
PubMed2006

Compliance analysis of phenylurea and related compounds in drinking water by liquid chromatography/electrospray ionization/mass spectrometry coupled with solid-phase extraction.

A liquid chromatography/electrospray ionization/mass spectrometry method was reported for the compliance analysis of seven phenylurea compounds and two related herbicides (tebuthiuron and propanil) in drinking water. The volumes of the sample and final extract used in the method were 500 mL and 10 mL, respectively. The obtained method detection limits were less than 0.03 microg/L, and the mean recoveries were 74-128% with a relative standard deviation of 2.6-8.3% for all the studied compounds. The peak-to-peak signal-to-noise ratios ranged from 3.3 for cis-siduron to 34.2 for fluometuron. The accuracy and precision resulting from reagent and drinking water samples fortified at higher concentration levels were similar to these results. Several analytes were detected in the drinking water samples, including tebuthiuron at 0.5 microg/L, propanil at 0.7 microg/L, diuron at 0.1-2.1 microg/L, and linuron at 0.1-0.8 microg/L.

Calibration↗
PubMed2006

A multi-element solid-phase extraction method for trace metals determination in environmental samples on Amberlite XAD-2000.

A method for the preconcentration of some transition elements at trace level was proposed using a column filled with Amberlite XAD-2000 resin. Metal ions were adsorbed on XAD-2000 as their diethyldithiocarbamate chelates, then analytes retained on the resin were eluted by 1 mol L(-1) nitric acid in acetone and determined by flame atomic absorption spectrometry (FAAS). The influences of some analytical parameters including pH of sample solution, ligand amount, the type, concentration and volume of elution solution, flow rates of the sample and eluent solutions, adsorption capacity of the resin and sample volume on the preconcentration efficiency have been investigated. The influences of some matrix elements were also examined. The detection limit (N=20, 3 sigma) for Mn(II), Fe(II), Co(II), Cu(II), Cd(II), Zn(II), Pb(II) and Ni(II) were found as 0.20, 0.35, 0.25, 0.20, 0.20, 0.15, 0.45 and 0.25 microg L(-1), respectively. The validation of the procedure was carried out by analysis of certified reference materials. The proposed method was applied to natural waters and kale vegetable (Brassica oleracea var. acephala).

Brassica↗
PubMed1992

Selective system of identification and determination of antidepressants and neuroleptics in serum or plasma by solid-phase extraction followed by high-performance liquid chromatography with photodiode-array detection in analytical toxicology.

A selective off-line solid-phase isolation of antidepressants, neuroleptics and other structurally related basic drugs from plasma or serum prior to high-performance liquid chromatography was tested and optimized for general use in toxicological analyses where concomitant drugs can be encountered. The sequential elution preseparated drug mixtures and simplified the subsequent analytical steps. High isolation efficiencies of cyano-bonded silica cartridges from Baker for fifteen amine drugs were determined. Isocratic chromatography on octadecylsilica proved to be very suitable for broad practical applications in complicated cases. The identification of an unknown peak was supported by photodiode-array detection in the range 200-400 nm with a resolution of 2 nm. The linearity of the assay from therapeutic to toxic concentrations was attained. Sufficient sensitivities covering low therapeutic levels of parent drugs and their demethylated metabolites were reached. The system is flexible and allows various methods of quantitative assay to be devised according to the conditions of a particular case in clinical or forensic toxicology.

Animals↗
PubMed1998

Determination of alternariol in tomato paste using solid phase extraction and high-performance liquid chromatography with fluorescence detection.

Alternaria spp. produce a wide variety of toxic metabolites with different chemical structures. Tomato products have been considered a likely source of Alternaria toxins in the human diet because Alternaria is an important spoilage mold of tomatoes. A new method for the determination of these mycotoxins in tomato paste, involving solid phase cartridges for extraction before HPLC fluorescence detection with a reversed phase column and isocratic elution, was developed. The method was demonstrated to be linear in the range 5.2-196 ppb of alternariol (AOH) in tomato paste. Good recoveries were obtained for AOH at all levels assayed (minimum 77.2%). The detection limit of the AOH toxin in real samples of tomato paste was low, 1.93 ppb. The precision of the method was demonstrated with a good repeatability (RSD = 2.98%) and reproducibility (RSD = 9.35%).

Calibration↗
PubMed2006

[Analysis of 37 drugs in whole blood by HPLC after solid phase extraction].

OBJECTIVE: To develop a specific, sensitive, reproducible SPE-HPLC method for the determination of 37 drugs in whole blood. METHODS: With the doxapram as internal standard, Oasis column was used to extract drugs from whole blood. Two kinds of mobile phases were used in this study. Separations were achieved by a LiChrospher 100 RP-C18 (250 mm x 4.0 mm x 5 microm) column kept at 50 degrees C, the DAD detector was set at 230 nm and 250 nm. RESULTS: The limit of detection were 1-30 ng/mL. The method showed excellent linearity and the linear correlation coefficient was > or =0.997 98. The relative standard deviation for between-day and within-day assay were <10%. CONCLUSION: The method is effective, simple, reliable and has been used in real cases.

Chromatography, High Pressure Liquid↗
PubMed2006

Molecular imprinting of natural flavonoid antioxidants: application in solid-phase extraction for the sample pretreatment of natural products prior to HPLC analysis.

As shown in the past years, SPE based on molecularly imprinted polymers (MIPs) may provide significant enhancement of selectivity in sample preparation and analyte preconcentration. The objective of this work was the fabrication of MIPs for the specific adsorption of rutin and quercetin. The two flavonoids were used as the template molecules for the preparation of MIP phases in a self-assembly (noncovalent) approach. The produced MIPs were validated with regard to the imprinting efficiency as media for LC and SPE. The retention behavior of several flavonoid compounds was studied using as stationary phases imprinted, control nonimprinted polymers, and commercial silica-based materials. MIPs were applied as materials for the selective SPE and preconcentration of the flavonoids from white and red wine, orange juice, and tea. The collected fractions were analyzed by high-pressure LC. MIP-SPE facilitated specific analyte isolation and effective sample clean-up. The results show that molecularly imprinted SPE can be a useful tool for the simple, selective, and cost-effective pretreatment of samples containing natural antioxidants.

Antioxidants↗
PubMed2002

A simple method for the determination of trace levels of alkylphenolic compounds in fish tissue using pressurized fluid extraction, solid phase cleanup, and high-performance liquid chromatography fluorescence detection.

A simple automated extraction method for the determination of alkylphenolic compounds in fish tissue is reported. Pressurized fluid extraction is used to extract ground fish tissue, and the resulting extract is purified on aminopropyl silica (APS) extraction cartridges. With no further sample preparation, nonylphenol (NP) and its ethoxylates, up to nonylphenol pentaethoxylate, are quantitated using normal phase (APS Hypersil) high-performance liquid chromatography with fluorescence detection. The major advantage of this technique is elimination of the conventional gel permeation cleanup step, a lengthy procedure designed to remove fish lipids. Spiked recoveries with lake trout averaged 85% for the six NP and NP ethoxylates that were investigated. Tissue concentrations of NP and NP ethoxylates determined in fish from various locations of the Great Lakes region ranged from 18 to 2075 ng/g, wet weight.

Animals↗
PubMedDate not supplied

Automated HPLC analyses of drugs of abuse via direct injection of biological fluids followed by simultaneous solid-phase extraction and derivatization with fluorescence detection.

An automated system is described for the simultaneous extraction and derivatization of nucleophilic compounds from various biological media. The method includes the use of a solid-phase reagent containing a 9-fluorenylacetate activated ester. The reagent is based on a controlled pore, polystyrene divinylbenzene support prepared through a silica template procedure. An X-Y-Z robotic arm equipped with a needle is used in conjunction with a syringe pump for aspirating and dispensing samples and standards into the HPLC system. A precolumn cartridge containing the solid-phase reagent is put on-line in place of the fixed-volume injection loop. Injections of biological fluids such as urine or plasma with minimal sample treatment and handling are made directly into this reactor. The analytes are derivatized as they are extracted, allowing virtually unlimited sample volumes to be injected. The polymeric cartridge can be used for up to 100 injections without accruing unacceptable reductions in sensitivity. A detection limit of 500 p.p.t. (parts per trillion) of amphetamine in urine was achieved with this system.

Acetates↗
PubMedDate not supplied

Determination of submicrogram-per-liter concentrations of caffeine in surface water and groundwater samples by solid-phase extraction and liquid chromatography.

A method for determining submicrogram-per-liter concentrations of caffeine in surface water and groundwater samples has been developed. Caffeine is extracted from a 1 L water sample with a 0.5 g graphitized carbon-based solid-phase cartridge, eluted with methylene chloride-methanol (80 + 20, v/v), and analyzed by liquid chromatography with photodiode-array detection. The single-operator method detection limit for organic-free water samples was 0.02 microgram/L. Mean recoveries and relative standard deviations were 93 +/- 13% for organic-free water samples fortified at 0.04 microgram/L and 84 +/- 4% for laboratory reagent spikes fortified at 0.5 microgram/L. Environmental concentrations of caffeine ranged from 0.003 to 1.44 micrograms/L in surface water samples and from 0.01 to 0.08 microgram/L in groundwater samples.

Caffeine↗
PubMed2006

Solid-phase extraction-gas chromatography and solid-phase extraction-gas chromatography-mass spectrometry determination of corrosion inhibiting long-chain primary alkyl amines in chemical treatment of boiler water in water-steam systems of power plants.

Gas chromatography with simultaneous flame-ionization detection (FID) and a nitrogen-phosphorus detection (NPD) as well as gas chromatography-mass spectrometry (GC/MS) has been used to characterize long-chain primary alkyl amines after derivatization with trifluoroacetic anhydride (TFAA). Electron impact ionization- (EI) and negative chemical ionization (NCI) mass spectra of trifluoroacetylated derivatives of the identified tert-octadecylamines are presented for the first time. The corrosion inhibiting alkyl amines were applied in a water-steam circuit of energy systems in the power industry. Solid-phase extraction (SPE) with octadecyl bonded silica (C18) sorbents followed by gas chromatography were used for quantification of the investigated tert-octadecylamines in boiler water, superheated steam and condensate samples from the power plant. The estimated values were: 89 microg l(-1)(n = 5, RSD = 7.8%), 45 microg l(-1) (n = 5, RSD = 5.4%) and 37 microg l(-1)(n = 5, RSD = 2.3%), respectively.

Amines↗
PubMed1998

Synergistic approaches based on nonchromatographic continuous separation techniques (solid-phase extraction and pervaporation) and chromatography couplings.

Approaches based on continuous separation units coupled to either liquid or gas chromatography for improving the features of analytical methods are proposed. Examples of solid-phase separation-liquid chromatography for the determination of fat-soluble vitamins and their metabolites in clinical samples, and pervaporation-gas chromatography for the determination of volatile compounds in solid environmental samples are described. The clean-up and preconcentration effect achieved by the former coupling and the easy and effective solid-sample pretreatment in the latter clearly show their utility. The use of pervaporation as an advantageous alternative to headspace is demonstrated.

Cholecalciferol↗
PubMed2004

Synthesis, characterization of silica gel phases-chemically immobilized-4-aminoantipyrene and applications in the solid phase extraction, preconcentration and potentiometric studies.

Two new 4-aminoantipyrene chemically-immobilized silica gel phases: ii (N,N-donor) and iii (N,O-donor), were synthesized and characterized by IR and surface coverage determination. The latter was accomplished by thermal desorption and metal probe methods, giving 0.300 and 0.312 mmol g(-1) for ii and 0.220 and 0.250 mmol g(-1) for iii. Moreover, potentiometric titration provided a surface coverage of 0.323 mmol g(-1) for ii. The metal capacity values in mmol g(-1) of ii, iii and the active silica gel phase i for a series of di- and trivalent metal ions were determined at pH 1.0 - 6.7. Phase i showed the lowest values, while ii and iii reflected higher affinity toward most of the metal ions. The highest values were 0.300 for Hg(II)-ii and 0.220 mmol g(-1) for Cd(II)-iii. Distribution coefficients (log Kd) were in the range of 3.57 - 4.76 for ii and 2.32 - 3.46 for iii, thus confirming certain selectivity characters of the solid extractors. The application of the phases as solid extractors and preconcentrators for some heavy metal ions is presented. Good percentage extraction and removal of 94 - 98 +/- 4 - 6% of the spiked 1.000 microg ml(-1) of Hg(II), Cd(II), Pb(II), Cu(II) and Zn(II) and good percentage recovery of 94 - 99 +/- 3 - 6% of 50 ng ml(-1) of these ions from tap water samples were obtained. Stability constants of H(I) and Cu(II) with ii for the two-phase mixture at 25 degrees C and I = 0.1 (KCI) were determined potentiometrically. The pKa of ii are 5.6 and 8.4, while the log K values for CuHL and CuL (L = ii) are 6.3 and 5.8, respectively, leading to the determination of several analytical data for Cu(II)-ii.

Journal Article↗
PubMed1989

Capillary gas chromatographic determination of epomediol in human plasma and urine using a rapid solid-phase extraction.

A simple and precise method for the quantitation of epomediol in human plasma and urine is described. Each biological sample is added with the internal standard and applied directly to an Extrelut-1 solid-phase column. After absorption the column is eluted with chloroform and the eluate is evaporated to dryness. The residue, reconstituted in ethanol, is analysed by capillary gas chromatography. No interferences from possible metabolites or endogenous constituents can be noted. The method has been applied to human pharmacokinetic studies: the results of a subacute administration to volunteers are presented.

Bridged Bicyclo Compounds, Heterocyclic↗
PubMed1995

Simultaneous determination of terbinafine (Lamisil) and five metabolites in human plasma and urine by high-performance liquid chromatography using on-line solid-phase extraction.

The antimycotic agent terbinafine (Lamisil) and five of its main metabolites were determined simultaneously in human plasma and urine samples by an isocratic HPLC method. The compounds were separated on a phenyl column following on-line solid-phase sample clean-up with a column-switching device. Terbinafine and its metabolites were detected by monitoring the column effluent with UV light at a wavelength of 224 nm. The linear range in plasma was assessed between 0 and 2500 ng/ml for the parent drug and metabolites V, IV and I. The linear response of metabolites III and II was assessed between 0 and 1250 ng/ml. In urine, linearity was assessed between 0 and 10,000 ng/ml for metabolites V, IV, III, II and between 0 and 1000 ng/ml for the parent drug and metabolite I. Quantification limits based on a C.V. < or = 20% and a bias < or = +/- 20% ranged from 20 to 500 ng/ml depending on the compound and the matrix. Inter-day and intra-day variations were similar indicating the ruggedness of the two methods. Due to the considerable differences in hydrophobicity between the compounds, extraction efficiencies ranged from 55 to 100%. Both methods were found to be reproducible and sufficiently sensitive for the evaluation of metabolite pharmacokinetics.

Autoanalysis↗