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PubMed2002

Determination of fluoroquinolone antibacterial agents in sewage sludge and sludge-treated soil using accelerated solvent extraction followed by solid-phase extraction.

A method for the quantitative determination of humanuse fluoroquinolone antibacterial agents (FQs) ciprofloxacin and norfloxacin in sewage sludge and sludge-treated soil samples was developed. The accelerated solvent extraction was optimized with regard to solvents and operational parameters, such as temperature, pressure, and extraction time. A 50 mM aqueous phosphoric acid/ acetonitrile mixture (1:1) was found to be optimum in combination with an extraction temperature of 100 degrees C at 100 bar, during 60 and 90 min for sewage sludge and sludge-treated soil samples, respectively. A cleanup step using solid-phase extraction substantially improved the selectivity of the method. Overall recovery rates for FQs ranged from 82 to 94% for sewage sludge and from 75 to 92% for sludge-treated soil, with relative standard deviations between 8 and 11%. Limits of quantification were 0.45 and 0.18 mg/kg of dry matter for sewage sludge and sludge-treated soils, respectively. The presented method was successfully applied to untreated and anaerobically digested sewage sludges and sludge-treated soils. Ciprofloxacin and norfloxacin were determined in sewage sludges from several wastewater treatment plants with concentrations ranging from 1.40 to 2.42 mg/kg of dry matter. Therefore, contrary to what may be expected for human-use pharmaceuticals, FQs may reach the terrestrial environment as indicated by the occurrence of FQs in topsoil samples from experimental fields, to which sewage sludge had been applied.

Anti-Infective Agents↗
PubMed1996

Comparison of new solid-phase extraction methods for chromatographic identification of drugs in clinical toxicological analysis.

OBJECTIVES: Newly presented solid-phase extraction methods (Solid Phase Disc Extraction, SPEC-Plus, Multi-Modal, and Solid Phase Micro Extraction, SPME have been checked with respect to their applicability to clinical toxicological analysis. In comparison with conventional liquid/liquid-extraction and a common mixed-phase column technology, their use in general screening and selective extraction methodology is discussed. DESIGN AND METHODS: Recovery studies were performed with urine-based samples including model substances, as well as drugs and metabolites from native urine samples. Chromatographic performance of the resulting extracts is presented in some examples. RESULTS: Liquid/liquid extraction, common mixed-phase column technique and the new SPEC-Plus, Multi-Modal disc extraction method gave the best recoveries with respect to broad-spectrum general screening. The purity of the concentrates was somewhat different, however. Solid-phase C18 and Solid-Phase Micro Extraction methodologies are better suited for selective drug extraction. In SPEC Disc or SPME extraction, the use of solvents is greatly reduced or omitted. Recovery of some volatile substances is enhanced. SPEC discs can be inserted directly into TLC chromatographic plates, SPME fibers into GC injection ports. CONCLUSIONS: The new solid-phase extraction technologies offer advantages in different respects: The mixed-phase disc extraction SPEC 1 Plus AR/MP3 Multi-Modal delivers promising results with respect to broad-spectrum general screening. Solvent consumption is low, throughput times are short, the extracts are clean, and recovery rates are good, comparable, or even higher than with common mixed-phase column techniques. The new SPME extraction method shows benefits in dedicated, selective extraction procedures (e.g., analysis of volatile substances such as amphetamines). Sampling is solvent-free, the handling is easy, and the yields of extraction are good, but only for selected substances. Broad-spectrum general screening still remains problematic with this technique. Further examinations have to be carried out including a larger number of drugs of toxicological relevance. Headspace sampling by SPME offers a good alternative to conventional mechanized sampling in the analysis of volatile substances in biological samples, omitting the need for expensive instrumentation.

Blood Chemical Analysis↗
PubMed1996

Determination of the anti-platelet-activating factor BN-50727 and metabolites in human urine by high-performance liquid chromatography using solid-phase extraction.

A sensitive and selective HPLC solid-phase extraction procedure was developed for the determination of platelet-activating factor antagonist BN-50727 and its metabolites in human urine. The procedure consisted in a double solid-phase extraction of the urine samples on cyanopropyl and silica cartridges, followed by an automated solid-phase extraction of the drug and metabolites on CBA cartridges and posterior elution on-line to the chromatographic system for its separation. The method allowed quantitation in the concentration range 10-2400 ng/ml urine for both BN-50727 and the main metabolite, the O-demethylated BN-50727 product. The limit of quantitation for both compounds was 10 ng/ml. The inter-assay precision of the method, expressed as relative standard deviation, ranged from 1.9 to 4.5% for BN-50727 and from 2.5 to 9.0% for the metabolite. The accuracy, expressed as relative error, ranged from -2.4 to 4.2% and from 0.2 to 6.2%, respectively. This paper describes the validation of the analytical methodology for the determination of BN-50727 in human urine and also for its metabolites. The method has been used to follow the time course of BN-50727 and its metabolites in human urine after single-dose administration.

Azepines↗
PubMed2000

Solid-phase extraction of polycyclic aromatic compounds.

Solid-phase extraction (SPE) for two groups of polyaromatic compounds--polycyclic aromatic hydrocarbons and naphthalenesulfonates--with completely different problems in the extraction process are reviewed. The sorbents used in each case and the different steps of SPE are studied. Particular problems encountered in the SPE of each group are described. Adsorption problems of PAHs which require an organic solvent or a surfactant to be added to the sample are explained. The need of ion-pair solid-phase extraction for extracting naphthalenesulfonates and the influence of the inorganic species in the extraction are discussed. The on-line systems are described for both group of compounds.

Chromatography, Gas↗
PubMed2005

Quantitation of binding, recovery and desalting efficiency of peptides and proteins in solid phase extraction micropipette tips.

Micropipette-tip solid phase extraction (SPE) systems are common in proteomic analyses for desalting and concentrating samples for mass spectrometry, removing interferences, and increasing sensitivity. These systems are inexpensive, disposable, and highly efficient. Here, we show micropipette-tip solid phase extraction is a direct sample preparation method for (14)C-accelerator mass spectrometry (AMS), removing salts or reagent from labeled macromolecules. We compared loading, recovery and desalting efficiency in commercially available SPE micro-tips using (14)C-labeled peptides and proteins, AMS, and alpha spectrometry ion energy loss quantitation. The polypropylene in the tips was nearly (14)C-free and simultaneously provided low-background carrier for AMS. The silica material did not interfere with the analysis. Alpha spectrometry provided an absolute measurement of desalting efficiency.

Equipment and Supplies↗
PubMed2000

Contributions of theory to method development in solid-phase extraction.

The kinetic and retention properties of solid-phase extraction devices are reviewed from the perspective of method development strategies. Models based on frontal analysis are used to correct retention properties of solid-phase extraction devices to account for the fact that too few theoretical plates are provided for retention to be independent of kinetic factors. The available pressure drop for the sampling device largely dictates the choice of useful particle sizes and maximum bed length. The use of octanol--water partition coefficients and extrapolated values of the retention factor obtained by liquid chromatography are poor empirical models for the estimation of breakthrough volumes with water as the sample solvent. The solvation parameter model provides an adequate description of sorbent retention for the estimation of breakthrough volumes, rinse solvent volume and composition, and elution solvent volume and composition. Combining the frontal analysis and solvation parameter models offers a comprehensive approach to computer-aided method development in solid-phase extraction. This is the first step in the development of a structure-driven approach to method development in solid-phase extraction that should be more reliable and less tedious than traditional trial and error approaches.

Chromatography, Liquid↗
PubMed1995

Evaluation of solid-phase extraction procedures in peptide analysis.

Solid-phase extraction (SPE) procedures for peptide isolation and fractionation, based on non-polar and ionic interactions, were evaluated using small synthetic peptides and casein enzymatic hydrolysates. SPE based on hydrophobic phases is a useful, efficient and rapid procedure for peptide extraction and concentration. It allows a successful peptide fractionation using eluents that contain an increasing content of acetonitrile in the presence of trifluoroacetic acid. Differences regarding selectivity are observed between sorbents. Non-polar interaction with C18 sorbents is adequate for the isolation of very polar and hydrophobic peptides. CN sorbents are only adequate for very hydrophobic peptides. PH, CH, C8 and C2 sorbents are useful for isolating and fractionating hydrophobic and very non-polar peptides, but generally not for very polar peptides. Ionic solid-phase extraction using Accell Plus cartridges of QMA (quaternary methylammonium) and CM (carboxymethyl) are very useful for the fractionation of peptide mixtures into basic, acidic and neutral pools of peptides. It can be concluded that SPE using these procedures is a useful tool for the isolation and fractionation of peptides from biological and food samples.

Amino Acid Sequence↗
PubMed1998

Simultaneous determination of imidazolinone herbicides from soil and natural waters using soil column extraction and off-line solid-phase extraction followed by liquid chromatography with UV detection or liquid chromatography/electrospray mass spectroscopy.

This paper describes the simultaneous quantification of the imidazolinone herbicides (IMIs) imazapyr, m-imazamethabenz, p-imazamethabenz, m,p-imazamethabenz-methyl, imazethapyr, and imazaquin in two types of samples. (a) Groundwater, lake water, and river water samples were enriched by off-line solid-phase extraction with a Carbograph-1 cartridge and analyzed by reversed-phase liquid chromatography using a UV detector (lambda = 240 nm). The overall recoveries of IMIs extracted from 1 L of groundwater (fortified with 500-100 ng/L), 0.5 L of lake water (fortified with 500-100 ng/L), and 0.5 L of river water (fortified with 1000-200 ng/L) samples were not lower than 89%. The mean relative standard deviation (RSD) was 5.1% (ranging from 4.1% to 6.8%) in natural water. The detection limits were 30-39 ng/L in groundwater, 43-51 ng/L in lake water, and 55-67 ng/L in river water. The method involves confirmatory analysis by LC/ES-MS in full-scan mode. The dependence of the ion signal intensities on proton concentration in the mobile phase was investigated with a view to optimizing the sensitivity of the ES-MS detector. When LC/ES-MS was used, the limit of detection, calculated from extracted-ion current profiles (EICPs), was 4-7 ng/L for ground-water and 9-13 ng/L for river water. (b) Soil sample analysis utilized combined soil column extraction (SCE) and off-line solid phase extraction (SPE) for sample preparation, analyzing with LC/ES-MS under selected ion monitoring (SIM). Several different extractants were evaluated for the purpose of SCE optimization. The system that best optimizes the extractability IMIs from the soil was found to be the mixture CH3OH/(NH4)2CO3 (0.1 M, 50:50 v/v). The effect of IMI concentration in the matrix on recovery was evaluated. The total recovery of each IMI from soil at each of the two levels investigated ranged from 87% to 95%. Under three ion SIM conditions, the limit of detection (S/N = 3) was 0.1-0.05 ng/g in soil samples.

Chromatography, High Pressure Liquid↗
PubMed2000

Solid-phase extraction for profiling of ecstasy tablets.

A solid-phase extraction (SPE) procedure has been developed for impurity profiling of illicit tablets containing 3,4-methylenedioxy-N-methyl-amphetamine (MDMA, ecstasy). Following initial comparison of liquid-liquid extraction and solid-phase extraction, SPE was found to be preferable because it afforded higher extraction efficiencies and shorter extraction times. Procedure blank samples were also analyzed to identify constituents of the extracts which did not originate in the ecstasy tablets. The developed procedure was subsequently applied to 12 samples of seized ecstasy tablets and a comparison was made of these samples to determine similarities and obtain inferences with respect to commonality of origin.

Chromatography, Gas↗
PubMed2006

Demonstration of a common artifact in immunosorbent assays of brain extracts: development of a solid-phase extraction protocol to enable measurement of amyloid-beta from wild-type rodent brain.

In the process of developing species-specific, immunosorbent assays for brain amyloid-beta (Abeta) in non-transgenic animals, we have demonstrated an artifact that impedes accurate quantitation of Abeta in this assay format. Using synthetic peptides, cerebrospinal fluid (CSF), or plasma samples, no nonspecific binding or cross-species immunoreactivity was detected in human or rodent Abeta assays. However, extracts of guinea pig brain (human Abeta sequence) or rat brain (rodent Abeta sequence) demonstrated immunoreactivity regardless of which capture antibody, detection antibody, or reporter method (colorimetric or fluorescent) was used. This immunoreactivity remained even in the absence of a capture antibody. Various blocking conditions failed to resolve the nonspecific binding of detection antibodies in the presence of brain extracts. Fractionation of DEA-extracted guinea pig brain over Sephadex G-50 demonstrated the feasibility of separating specific from nonspecific binding components in the brain extracts. Thus, a solid phase extraction method, compatible with multiple extraction buffers, has been developed to isolate and concentrate Abeta from brain extracts. This isolation method eliminates non-specific binding components from brain extracts and allows for accurate quantitation and robust detection of multiple Abeta peptides in extracts from wild-type animals.

Amyloid beta-Peptides↗
PubMed2000

Solid-phase extraction for combinatorial libraries.

Solid-phase extraction (SPE) has during the last three years emerged as a convenient method for the purification of compound libraries prepared by solution synthesis. The widespread use of SPE in combinatorial chemistry can be explained by straightforward SPE method development facilitated by the availability of numerous commercial SPE resins. High-speed automated SPE is readily accomplished by taking advantage of commercial laboratory robot systems. The present review summarizes and discusses advancements made in the use of different SPE resins and molecule tagging techniques for optimization of ion-exchange, reversed-phase, normal-phase and fluorous-phase SPE in combinatorial chemistry.

Chromatography, Liquid↗
PubMed2001

Determination of the adenosine A(1) agonist N(6)-cyclopentyladenosine in rat blood by solid-phase extraction and HPLC.

A solid-phase extraction procedure has been developed for the isolation of the adenosine A1 receptor agonist N(6)-cyclopentyladenosine from rat blood. The biological samples were spiked with N(6)-cyclopentyladenosine and the analogue N(6)-cyclohexladenosine (internal standard), diluted with sodium hydroxide, loaded onto disposable cartridges with subsequent desorption with methanol and analysis by HPLC. The performance of columns pre-packed with different C18-bonded silica phases or with a polymeric reversed-phase sorbent (Oasis HLB) was assessed. The highest extraction efficiencies (recovery rates>83.3%) for the two N6-alkyl substituted adenosines were achieved by the Oasis HLB cartridges. In addition, the polymeric sorbent provided reproducible recoveries (relative standard deviation<4.8%), whereas large variations (relative standard deviation values, 9--16.3%) in the extraction yields were observed using the conventional silica-based C18 cartridges. The described sample preparation method is rapid, simple, selective and it is suitable for pharmacokinetic studies.

Adenosine↗
PubMed1998

Automated sample preparation for drugs in plasma using a solid-phase extraction workstation.

An automated solid-phase extraction workstation was used to develop, characterize and validate two separate HPLC methods for quantifying drugs in plasma. Method development was facilitated by workstation functions which allowed wash solvents of varying organic composition to be mixed and tested automatically. The precision estimates for the two methods were within 6.0 and 2.0% RSD across their respective calibration ranges. Accuracies for replicate determinations of quality controls were between -1.2 and +4.8 RE over ng ml-1 calibration ranges, respectively. Optimized recoveries were quantitative and were generally greater than 90% for the four analytes tested, and depended to a great extent, as expected, on the composition of the wash solvent. Sample throughput benchmarks for the two methods ranged from 3 to 10 min per sample, depending on the extent of air drying used. Because of parallel sample processing, 60 samples could be extracted in as little as 17 min.

Blood Chemical Analysis↗
PubMed1999

Rapid screening for organochlorine and organophosphorus pesticides in milk using C18 and graphitized carbon black solid phase extraction cleanup.

A rapid, multiresidue, solid phase extraction (SPE) technique for the isolation and gas chromatographic determination of organochlorine and moderately polar organophosphorus pesticide residues in milk is described. Milk is sonicated with an acetonitrile-acetone-methanol mixture and centrifuged. The supernatant is subjected to a cleanup using both C18 and graphitized carbon black SPE columns. The pesticide residues are determined by gas chromatography with electron capture and flame photometric detection. The method required minimal volumes of solvent and resulted in the production of minimal volumes of hazardous waste.

Animals↗
PubMed2000

A procedure for fractionation of sphingolipid classes by solid-phase extraction on aminopropyl cartridges.

Solid-phase extraction (SPE) methods are easy, rapid, and reliable. Their growing popularity is in part due to their operational simplicity and cost reduction in solvents, and partly because they are easier to automate. Sphingolipids are implicated in various cellular events such as growth, differentiation, and apoptosis. However, their separation by small SPE cartridges has attracted limited attention. Here we describe an SPE procedure on aminopropyl cartridges that by sequential elution allows the separation of a lipid mixture into free ceramides, neutral glycosphingolipids, neutral phospholipids (sphingomyelin), and a fraction containing the acidic phospholipids and phosphorylated sphingoid bases, phosphoceramides and sulfatides. Individual components are obtained in high yield and purity. We applied the procedure to obtain data on separation of [(3)H]myristic acid-labeled sphingolipids from fish gills, and from human melanoma tumor tissue. Individual lipids in the SPE fractions were identified by chromatography on several high-performance thin-layer chromatography (HPTLC) systems. The chromatographic behavior of free sphingoid bases is also reported.

Animals↗
PubMed2005

[Determination of organochlorine pesticide residues in nine herbs by solid-phase extraction and capillary gas chromatography].

The solid-phase extraction and capillary gas chromatography was introduced for determining 13 organochlorine pesticide residues including alpha-benzene hexachloride (BHC), betaBHC, gamma-BHC, delta-BHC, p,p'-dichloro-diphenyl-dichloroethylene (pp'-DDE), p,p'-dichloro-di-phenyl-dichloroethane (pp'-DDD), o,p'-dichloro-diphenyl-trichloroethane (op'-DDT), pp'-DDT, heptachlor (HEPT), aldrin, heptachlor epoxide (HCE), dieldrin and endrin in Scutellaria baicalensis, Salvia miltiorrhiza, Belamcanda chinensis, Paeoniae lactiflora, Angelica dahurica, Arisaema erubescens, Fructus arctii, Anemarrhena asphodeloides and Platycodon grandiflorum. The organochlorine pesticides were extracted from herbs with mixed solvents of acetone and n-hexane by ultrasonic and cleaned up by Florisil solid-phase extraction column. Then, the extract was separated by capillary column (30 m x 0.25 mm i.d. x 0.25 microm) and detected by electrochemical detector. The carrier gas was N2 (99.999%) with the flow rate of 1.4 mL/min. The split ratio was 1:2.2. The injector temperature was 220 degrees C and the detector temperature was 330 degrees C. The column temperature was increased by the rate of 20 degrees C/min from 100 degrees C to 190 degrees C (hold for 1. 0 min), then to 235 degrees C by the rate of 4 degrees C/min and hold for 7 min at 235 degrees C. The good linearities were obtained for 13 organochlorine pesticides. The detection limits were between 0.064-0.61 microg/L. The average recoveries were between 87.3%-102.3% and relative standard deviations of 1.3%-6.8%. The method is effective, fast and accurate.

Capillary Electrochromatography↗
PubMed2006

Solid-liquid extraction and cation-exchange solid-phase extraction using a mixed-mode polymeric sorbent of Datura and related alkaloids.

Tropane alkaloids solid-liquid extraction methods were developed and comprised ambient pressure ones: extraction with hot solvent, extraction at room temperature, on ultrasonic bath as well as pressurised liquid extraction (PLE) techniques. The highest yields of l-hyoscyamine in methanol PLE method (3 x 5 min, 110 degrees C) and scopolamine extracted with 1% tartaric acid in methanol (15 min, 90 degrees C) were determined. A mixed-mode reversed-phase cation-exchange solid-phase extraction (SPE) procedure was optimised for simultaneous recoveries of L-hyoscyamine, scopolamine, scopolamine-N-oxide from plant extracts as well as quaternary alkaloid representative: scopolamine-N-methyl bromide. First three alkaloids were efficiently eluted (recoveries 80-100%) from an Oasis MCX cartridge with methanol-10% ammonia (3:1, v/v) solution, whereas for the quaternary salt tetrahydrofuran-methanol-25% ammonia (6:1:3, v/v) was used with recoveries 52-6%. HPTLC-densitometric assay on silica gel plates was elaborated at 205 nm without derivatization and included: single development (over a distance 9.5 cm) with acetone-methanol-water-25% ammonia (85:5:5:8, v/v) mobile phase for L-hyoscyamine and scopolamine separation, whereas for scopolamine-N-oxide and scopolamine-N-methyl bromide a second development (to a distance 5.5 cm) with acetonitrile-methanol-85% formic acid (120:5:5, v/v) was applied. Newly elaborated RP-HPLC-diode array detection method was performed on Waters XTerra RP-18 column with gradient of acetonitrile in 15 mM ammonia solution and alkaloids were baseline separated within 20 min. Both chromatographic methods were validated and their quantitative results were compared. Good correlation between HPLC and HPTLC quantitative results was measured (correlation coefficients of mean values were 0.92086 and 0.99995 for L-hyoscyamine and scopolamine, respectively). In the RP-HPLC method, which was from 1.5- up to 7-fold more sensitive than HPTLC, limits of detection (LOD) and limits of quantitation (LOQ, in bracket) were (in ng/microl) as follows: 0.25 (0.82) for L-hyoscyamine, 0.29 (0.97) for scopolamine, 0.13 (0.45) for scopolamine-N-oxide and 0.58 (1.91) for scopolamine-N-methyl bromide. By the use of the optimised chromatographic methods, 14 various samples from the leaves and fruits of Datura sp. were screened for L-hyoscyamine and scopolamine contents and the most promising samples were established.

Alkaloids↗