SEARCH · PubMed Health

Results for “Analytic Sample Preparation Methods”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources

PubMed1998

A novel ETA-AAS background reduction method for determination of lead and cadmium in urine.

Urinary lead and cadmium level were determined in double diluted urine samples using two modifiers: 1% HNO3 (own modification) and 1.6% NH4H2PO4 that is generally used for matrix modification. The background signal is reduced in the samples diluted with 1% HNO3 because of the modifying effect of nitric acid. Lower variation coefficients were obtained in a run of 10 determinations of each of the samples processed by our method which is an advantageous feature compared with the method using 1.6% NH4H2PO4 as a modifier. Recovery is between 95 and 105% for both methods. The analytical performance, flexible pre-instrumental preparation and minimized risk of sample contamination make the use of 1% HNO3 modifier a reliable method in the routine practice of determination of the urinary Pb and Cd level.

Cadmium↗

PubMed2003

Simultaneous sample preparation and species-specific isotope dilution mass spectrometry analysis of monomethylmercury and tributyltin in a certified oyster tissue.

A rapid, accurate, sensitive, and simple method for simultaneous speciation analysis of mercury and tin in biological samples has been developed. Integrated simultaneous sample preparation for tin and mercury species includes open focused microwave extraction and derivatization via ethylation. Capillary gas chromatography-inductively plasma mass spectrometry (CGC-ICPMS) conditions and parameters affecting the analytical performance were carefully optimized both for species-specific isotope dilution analysis of MMHg and TBT and for conventional analysis of MBT and DBT201Hg-enriched monomethylmercury and 117Sn-enriched tributyltin were used for species-specific isotope dilution mass spectrometry (SIDMS) analysis. As important, accurate isotope dilution analysis requires equilibration between the spike and the analyte to achieve successful analytical procedures. Since the spike stabilization and solubilization are the most critical and time-consuming steps in isotope dilution analysis, different spiking procedures were tested. Simultaneous microwave-assisted spike stabilization and solubilization can be achieved within less than 5 min. This study originally introduces a method for the simultaneous speciation and isotope dilution of mercury and tin in biological tissues. The sample throughput of the procedure was drastically reduced by fastening sample preparation and GC separation steps. The accuracy of the method was tested by both external calibration analysis and species-specific isotope dilution analysis using the first biological reference material certified for multielemental speciation (oyster tissue, CRM 710, IRMM). The results obtained demonstrate that isotope dilution analysis is a powerful method allowing the simultaneous speciation of TBT and MMHg with high precision and excellent accuracy. Analytical problems related to low recovery during sample preparation are thus minimized by SIDMS. In addition, a rapid procedure allows us to establish a performant routine method using CGC-ICPMS technique.

Animals↗

PubMed2005

Development of an electrospray ionization mass spectrometric method for the quantification of theophylline in horse serum.

A rapid and selective method has been developed for the determination of theophylline in horse serum by LC-ESI/MS/MS. The analytical method includes a protein precipitation extraction for sample preparation, liquid chromatography separation technique and ionspray tandem mass spectrometry. The drug was extracted from serum using a protein precipitation with acetonitrile and the supernatants were analyzed using an LC-ESI/MS/MS instrument. The chromatography was performed using a 50 x 2.1 mm C(8) analytical column and an isocratic mobile phase composes of 60:40 acetonitrile-0.5% formic acid in water with a flow rate fixed at 350 microL/min. A linear (weighted 1/concentration) relationship was used to perform the calibration over an analytical range of 0.1-20 ppm. The intra-batch precision and accuracy at LLOQ, medium and high concentration were 11.7, 6.9 and 5.4% and 95.8, 107.8 and 95.8%, respectively, and the inter-batch precision and accuracy at LLOQ, medium and high concentration were 10.4, 7.9 and 7.3% and 97.3, 105.2 and 95.9%, respectively. This LC-ESI/MS/MS method for the determination of theophylline in horse serum has been proved to within generally accepted criteria used for bioanalytical assay and was used successfully during clinical investigation.

Animals↗

PubMed2005

Quantitative determination of perfluorooctanoic acid in serum and plasma by liquid chromatography tandem mass spectrometry.

A selective and sensitive method for analysis of perfluorooctanoic acid (PFOA) in human serum and plasma, utilizing liquid chromatography tandem mass spectrometry (LC-MS/MS), has been developed and thoroughly validated to satisfy strict FDA guidelines for bioanalytical methods. A simple, automated sample preparation procedure, involving extraction of the target analyte with acetonitrile on protein precipitation media in a 96-well plate format was developed, allowing efficient handling of large numbers of samples. The proposed method uses the calibration standards prepared in a surrogate matrix (rabbit serum or plasma) and (13)C-labeled PFOA as the internal standard to account for matrix effects, instrument drift, and extraction efficiency. Human serum and plasma could not be used for matrix matching of calibration standards as endogenous levels of PFOA observed in the control human serum and plasma significantly exceeded the targeted lower limit of quantitation (LLOQ) of the method. Precision and accuracy of the method were demonstrated by analysis of rabbit serum and plasma control samples fortified at 0.5, 5, and 40 ng/mL PFOA and human serum and plasma fortified at 1.0, 5.0, 40 ng/mL PFOA. The LLOQ of 0.5 ng/mL PFOA was experimentally demonstrated for rabbit and human serum and plasma. Within-day precision and accuracy, short-term stability, freeze-thaw stability, equivalence of response between PFOA and APFO (the ammonium salt of PFOA), and dilution of concentrated samples were also investigated. The results of the validation experiments comply with the precision and accuracy limits defined by the FDA guidance document: "Guidance for Industry, Bioanalytical Method Validation", May 2001.

Animals↗

PubMed2001

Organic ion imaging of biological tissue with secondary ion mass spectrometry and matrix-assisted laser desorption/ionization.

Organic secondary ion mass spectrometry (SIMS) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry can be used to produce molecular images of samples. This is achieved through ionization from a clearly identified point on a flat sample, and performing a raster of the sample by moving the point of ionization over the sample surface. The unique analytical capabilities of mass spectrometry for mapping a variety of biological samples at the tissue level are discussed. SIMS provides information on the spatial distribution of the elements and low molecular mass compounds as well as molecular structures on these compounds, while MALDI yields spatial information about higher molecular mass compounds, including their distributions in tissues at very low levels, as well as information on the molecular structures of these compounds. Application of these methods to analytical problems requires appropriate instrumentation, sample preparation methodology, and a data presentation usually in a three-coordinate plot where x and y are physical dimensions of the sample and z is the signal amplitude. The use of imaging mass spectrometry is illustrated with several biological systems.

Animals↗

PubMed1999

Rapid mass spectrometric analysis for ascorbate and related organic acids in small volumes of plasma for use in pediatric subjects.

A gas chromatographic-mass spectrometric isotope dilution method was developed for analysis of ascorbate on 10 microl samples of plasma. This assay was reproducible (standard deviation of less than 4%) and gave values for plasma ascorbate content within 8% of our previously published gas chromatographic-mass spectrometric method. Non-specific sample preparation allowed other analytes to be determined on the same sample by adjusting data acquisition parameters and adding the appropriate internal standard. Analysis on 28 subjects fell within the expected range for plasma ascorbate 68+/-29 microm (11.9+/-5.0 microg/ml) and established a normal range for plasma threonate of 28.1+/-2.4 microm (3.8+/-0.4 microg/ml).

Ascorbic Acid↗

PubMed2006

Determination of seven organosulfur compounds in garlic by high-performance liquid chromatography.

The properties of garlic (Allium sativum L.) are attributed to organosulfur compounds. Although these compounds change during cultivation and storage, there is no report of their simultaneous analysis. Here, a newly developed analytical method with a rapid and simple sample preparation to determine four sulfoxides and three gamma-glutamyl peptides in garlic is reported. All garlic samples were simply extracted with 90% methanol solution containing 0.01 N hydrochloric acid and prepared for analysis. Alliin, isoalliin, methiin, cycloalliin, and gamma-l-glutamyl-S-methyl-l-cysteine were determined by normal-phase HPLC using an aminopropyl-bonded column. gamma-l-Glutamyl-S-(2-propenyl)-l-cysteine and gamma-l-glutamyl-S-(trans-1-propenyl)-l-cysteine were separated on an octadecylsilane column. The overall recoveries were 97.1-102.3%, and the relative standard deviation values of intra- and interday precision were lower than 2.6 and 4.6%, respectively. This newly developed method offers some advantages over the currently accepted techniques including specificity, speed, and ease of use and would be useful for chemical and biological studies of garlic and its preparations.

Chromatography, High Pressure Liquid↗

PubMed2005

A novel separation-free assay technique for serum antibodies using antibody bridging assay principle and two-photon excitation fluorometry.

A new technique for separation-free detection of antigen-specific antibodies is presented. The new technique employs antibody bridging assay principle and the recently developed ArcDia TPX fluorescence detection technology. According to the assay scheme, antibody molecules from the sample bind with one arm to an antigen on polymer microspheres and with the other arm to a fluorescently labeled secondary antigen reagent. Consequently, fluorescent immunocomplexes are formed on the surface of microspheres in proportion to the concentration of the analyte in the sample. The fluorescence signal from individual microspheres is measured by means of two-photon excited fluorescence detection. In order to demonstrate the applicability of the new assay technique, an assay for anti-adenovirus antibodies was constructed. The function of the assay method was tested both with monoclonal anti-adenovirus antibody preparation (standard analyte), and with positive serum samples. Standard class-specific ELISA was used as a reference method. The new assay method provides comparable sensitivity and precision, and wider dynamic range for IgG antibodies than the ELISA method. The standard curve showed linear response (R(2)=0.999) with a dynamic range of three orders of magnitude, detection limit (mean+3S.D.) of 8 pM, and intra-assay signal precision of 5%. Applicability of the new method for clinical serodiagnostics is discussed.

Animals↗

PubMed2003

Use of ionic liquids for liquid-phase microextraction of polycyclic aromatic hydrocarbons.

This paper demonstrates, for the first time, that ionic liquids (IL) such as 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)MIM][PF(6)]) are excellent extraction solvents in liquid-phase microextraction (LPME). The unique properties of nonvolatility and adequate viscosity allow IL to be conveniently adopted as extraction solvents in both direct-immersion and headspace LPME. Model compounds, polycyclic aromatic hydrocarbons (PAHs), are conveniently and rapidly enriched in a 3-microL drop of [C(8)MIM][PF(6)] suspended on the tip of a microsyringe followed by liquid chromatographic determination. Compared to 1-octanol, a larger volume drop of [C(8)MIM][PF(6)] can be formed and survive for a longer extraction time; therefore, a much higher enrichment factor for PAHs can be reached. For low-volatility PAHs, direct-immersion LPME provides higher enrichment factors than that of headspace LPME. However, the enrichment factor obtained by headspace LPME was almost 3-fold of that by direct-immersion LPME in a 30-min extraction of the most volatile PAH, naphthalene. For 30-min direction-immersion LPME of EPA priority PAHs, the enrichment factor, correlation coefficient (R(2)), and reproducibility (RSD, n = 5) were in the range of 42-166, 0.9169-0.9976, and 2.8-12%, respectively. Considering that IL can be easily prepared from relatively inexpensive materials and tuned by combination of different anions and cations for task-specific extraction of analytes from various solvent media, this proposed method should have great potentiality in sample preparation. Furthermore, the nonvolatility of IL makes it potentially useful for headspace LPME of volatile analytes.

Journal Article↗

PubMed2006

High-performance liquid chromatographic determination of the magnetic resonance imaging contrast agent Gadocoletate ion in human plasma, urine and faeces.

Gadocoletate ion is a new paramagnetic intravascular contrast agent for magnetic resonance imaging (MRI). An high-performance liquid chromatographic method for assaying Gadocoletate ion in human plasma, urine and faecal samples is described. The analysis is based on the reversed-phase chromatographic separation of Gadocoletate ion from the endogenous components of the biological matrices and its detection during elution by ultraviolet light absorption at 200 nm. The selectivity of the method was satisfactory. The mean absolute recovery during the analytical sample preparation was greater than 87%. The precision, expressed as coefficient of variation (CV%) ranged from 0.29 to 5.90% and the accuracy, expressed as mean relative error (R.E.%) of the analytical method ranged from -3.7 to +7.1%. The detection limit in plasma and urine was 2.01 and 10.0 microg/mL (0.00203 and 0.0101 micromol/mL), respectively. The detection limit in homogenized faecal samples was 17.7 microg/g (0.0179 micromol/g). Stability studies were performed in human plasma and urine samples during the analytical cycle. Gadocoletate ion was shown to be stable in human plasma and in human urine when stored at about +4 degrees C for up 24 h, and after three freeze-thaw cycles. In addition, it was shown to be stable in samples of processed plasma and in diluted urine at about +4 degrees C for 48 h, and at room temperature for at least 24 h. As regards the long-term stability of Gadocoletate ion, the results of dedicated studies showed that Gadocoletate ion is stable in human plasma samples when stored at +4 degrees C for up to 30 days and at -80 degrees C for up to 90 days. Gadocoletate ion is stable in samples of human urine when stored at +4 degrees C for up to 30 days, and when stored at -20 degrees C and at -80 degrees C for up to 90 days. The method has been successfully validated in human plasma, urine and faeces and it has been shown to be precise, accurate and reliable.

Chromatography, High Pressure Liquid↗

PubMed1981

Quantitative determination of 1,2-dibromo-3-chloropropane in whole rat blood and drinking water by gas chromatography.

1,2-Dibromo-3-chloropropane (DBCP) in an amber-colored liquid that has been used as a soil fumigant for nematodes since 1957 in agricultural cropland. Formulations containing DBCP have been primarily sold under the trademarks Fumazone (Dow Chemical, Midland, MI, U.S.A.) and Nemagon (Shell, THe Hague, The Netherlands). Recent reports have associated exposure to DBCP with disruption of spermatogenesis and azoospermia or oligospermia in male workers. Tests on laboratory animals have indicated that DBCP has an adverse effect on spermatogenesis and leads to testicular atrophy. In support of DBCP studies in animals, an analytical method was developed to determine low-level concentrations of DBCP in whole blood. Previous analytical methods for DBCP in blood required extensive sample preparation and steam distillation which limits the number of analysis per time period. This paper describes a simple gas chromatographic-electron-capture detection (GC-ECD) method that is both specific and sensitive to DBCP blood levels at concentrations as low as 2.28 x 10(-1) ng/ml DBCP. In addition, a quantitative analytical method was developed to measure levels of DBCP in drinking water which parallels the method in blood.

Animals↗

PubMed2000

Techniques for sample preparation including methods for concentrating peptide samples.

In the current era of proteomics two main analytical techniques are employed for protein identification. By far the fastest and most sensitive procedure for protein identification employs biological mass spectrometry, while de novo sequence analysis by classical Edman degradation is currently diminishing. In order to achieve the highest sensitivity for both techniques, great demands need to be put on sample preparation. In this paper we review three different aspects of protein sample preparation. Firstly, we discuss the use of polyacrylamide or agarose gel systems in which, during electrophoresis, proteins present in multiple primary gel pieces are eluted and simultaneously concentrated in a small secondary gel volume, whereby the overall sensitivity of Edman sequencing can be greatly increased. In a second chapter we review automation strategies occurring in the protein field which allow the automatic handling of multiple protein spots at the same time. In this context, we describe the use of auto-sampling techniques for further mass spectrometric studies and protein digestion robots allowing the simultaneous preparation of tens of gel-separated proteins. Finally we discuss various strategies for the preparation of biological peptide samples such as protein digests for both matrix-assisted laser desorption ionisation and electrospray ionisation mass spectrometry.

Automation↗

PubMed2003

Feasibility of supercritical fluid extraction with on-line coupling of reversed-phase liquid chromatography for quantitative analysis of polymer additives.

An on-line analytical method for determining polymer additives which incorporates (a) sample preparation and concentration, (b) chromatographic separation, and (c) UV detection is presented. The on-line system which combines supercritical fluid extraction (SFE) and high-performance liquid chromatography (LC) allows analytes to first be extracted and transferred to the SFE sorbent trap, then desorbed from the trap and presented to the LC system. No UV detector interference from residual dissolved CO2 in the mobile phase was observed since CO2 is eliminated by a pre-wash of the sorbent trap with a small amount of water. Reversed-phase LC with a mobile phase gradient of acetonitrile-water was employed. The described method allows a complete analysis to be processed in less than 30 min.

Chromatography, Liquid↗

PubMed2006

First LC-MS/MS electrospray ionization validated method for the quantification of perindopril and its metabolite perindoprilat in human plasma and its application to bioequivalence study.

A high throughput bioanalytical method based on solid phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS), has been developed for the estimation of perindopril and its metabolite perindoprilat, an angiotensin-converting enzyme inhibitor in human plasma. Ramipril was used as internal standard (IS). The extraction of perindopril, perindoprilat and ramipril from the plasma involved treatment with phosphoric acid followed by solid phase extraction (SPE) using hydrophilic lipophilic balance HLB cartridge. The SPE eluate without drying were analyzed by LC-MS/MS, equipped with turbo ion spray (TIS) source, operating in the negative ion and selective reaction monitoring (SRM) acquisition mode to quantify perindopril and perindoprilat in human plasma. The total chromatographic run time was 1.5 min with retention time for perindopril, perindoprilat and ramipril at 0.33, 0.35 and 0.30 min. The developed method was validated in human plasma matrix, with a sensitivity of 0.5 ng/ml (CV, 7.67%) for perindopril and 0.3 ng/ml (CV, 4.94%) for perindoprilat. This method was extensively validated for its accuracy, precision, recovery, stability studies and matrix effect especially because the pattern of elution of all the analytes appears as flow injection elution. Sample preparation by this method yielded extremely clean extracts with very good and consistent mean recoveries; 78.29% for perindopril, 76.32% for perindoprilat and 77.72% for IS. The response of the LC-MS/MS method for perindopril and perindoprilat was linear over the range 0.5-350.0 ng/ml for perindopril and 0.3-40 ng/ml for perindoprilat with correlation coefficient, r>/=0.9998 and 0.9996, respectively. The method was successfully applied for bioequivalence studies in human subjects samples with 4 mg immediate release (IR) formulations.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1999

Direct determination of stability of protease inhibitors in plasma by HPLC with automated column-switching.

Automated column-switching HPLC methods were developed and utilized for the direct analyses of three hydroxamic acid based metalloprotease inhibitors in rat plasma. These column-switching methods involved the use of a restricted-access media (RAM) precolumn and a column-switching valve, allowing the complete automation of sample preparation and HPLC. The plasma samples were directly injected onto a precolumn packed with SPS/ODS stationary phase and then backflushed onto an ODS analytical column using a 6-port column-switching device. The drug stability in rat plasma was determined using both the automated and traditional HPLC methods. The results obtained from the automated column-switching methods were in good agreement with those from traditional methods that involve sequential protein precipitation, liquid extraction, solvent evaporation, and sample reconstitution. In addition to the elimination of labor-intensive and time-consuming sample preparation procedures, the column-switching methods allowed on-line analyte enrichment and accurate determination of drug stability in plasma with detection limits in the range of 10-20 ng/ml(-1). This work represents, for the first time, a drug stability study in plasma by automated column-switching HPLC technique with the use of a RAM column. Our column-switching methods can be readily adapted to any existing HPLC system with minimal hardware modification.

Animals↗

PubMed2000

Analysis of pigmented high-molecular-mass grape phenolics using ion-pair, normal-phase high-performance liquid chromatography.

A normal-phase LC method has been developed to analyze high-molecular-mass grape phenolic compounds. Samples are prepared by first isolating phenolics using C18-SPE. The analytical method uses a silica column and gradient elution with mobile phases of methylene chloride, methanol, formic acid and heptanesulfonic acid. This separation enables the analysis of these compounds from grape and wine samples in the presence of anthocyanins without extensive purification. Based on the elution order of proanthocyanidins and anthocyanins, phenolics elute in order of increasing molecular mass. Currently, it is not possible to identify all of the components separated in the chromatogram.

Anthocyanins↗

PubMed2005

Isotope dilution determination of polycyclic aromatic hydrocarbons in olive pomace oil by gas chromatography-mass spectrometry.

A gas chromatographic (GC) method with mass spectrometry detection (MS) for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in olive pomace oil has been developed. The oil was diluted with n-pentane and extracted by liquid-liquid partition with dimethyl sulphoxide (DMSO). After water addition and back-extraction with cyclohexane, a thin-layer chromatography on silica gel was performed as a further purification step. The PAHs spot was scraped off from the plate and the final extract was concentrated and analysed by GC-MS in full scan mode. The eight PAHs under investigation were determined in the presence of the corresponding labelled compounds added as internal standards to the sample at the beginning of the analytical process. The identified PAHs were then quantified by the isotope dilution methodology assuring the compensation of the concentration of each analyte for any variation in the sample preparation. The method precision was satisfactory with relative standard deviation (R.S.D.) values in the range 3.6-12.7% for all PAHs. The average recovery rates ranged from 69.0 to 97.5%. Accuracy was also calculated for benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene and benzo[ghi]perylene by analysing a certified reference material (CRM 458, coconut oil) with adequate results. All response curves exhibited a linear fit from 0.1 to 10 microg ml(-1) and the determination coefficients R2 were better than 0.9942. The limits of detection (0.1-0.4 microg kg(-1)) were acceptable when compared with the maximum permitted limit of 2 microg kg(-1) for each of the eight considered PAHs and 5 microg kg(-1) for the sum of the eight PAHs established by the Italian legislation. Measurement uncertainty was finally calculated identifying and quantifying the uncertainty components of the analytical process. The relative expanded uncertainties (Uc), expressed as percent values were in the range 8.5-11.4% thus appropriate for residues quantification in the range of concentrations considered in the present study.

Gas Chromatography-Mass Spectrometry↗

PubMed2006

Multisample preparation methods for the solvent-free MALDI-MS analysis of synthetic polymers.

A limitation of any current approach using solvent-free MALDI mass spectrometry is that only one sample at a time can be prepared and transferred to the MALDI-plate. For this reason, multiple-sample preparation approaches for solvent-free MALDI MS analysis of synthetic polymers were developed that are simple and practical. One approach multiplexed sample preparation by simultaneously preparing multiple samples. With this approach, as many as 384 samples could be prepared by addition of analyte, matrix, salt, and 1-mm metal beads to each well of a 384-well disposable bacti plate, capping the plate with the lid and homogenizing all samples simultaneously using a common laboratory vortex device. Besides the time savings achieved by a single vortex step for multiple samples, an additional advantage of this method relative to previously reported solvent-free preparation methods is that the mixing volume per sample is reduced, which allows a reduction in the amount of analyte required. This method, however, still requires the transfer of each homogenized sample to the MALDI plate for subsequent analysis. Here we report a novel approach that combines multiple simultaneous solvent-free sample preparation with automatic sample transfer to the MALDI target plate. This approach reduces the possibility of cross-contamination, the amount of sample and matrix consumed for an analysis, and the time required for preparation of multiple samples. These methods were shown to provide high-quality mass spectra for various synthetic polymer standards with M(n) values to 10 kDa. The methods are efficient in that small sample amounts are required, the sample/salt/matrix ratio is not critical, and the time necessary to achieve sufficient homogenization of multiple samples is less than 5 min.

Chemistry Techniques, Analytical↗