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At least 307 records · Page 17Linked to original sources
PubMed1999

[Sample preparation for electron microscope with tissues fixed with formalin and embedded in paraffin].

A method of sample preparation for electron microscope is introduced. After paraffin-embedded tissues, fresh and fixed on time, were deparaffined, the tissue were fixed in 4% glutaraldehyde for 24 hours, in 1% osmic acid for 1-2 hours, and dehydrated with acetone and embedded in Epon812; then they were cut into ultrathin sections. By this method, better ultrastructure of paraffin-embedded tissues was obtained, and the method could satisfy the demand for observation under electron microscope. In addition, some important proceedings were also discussed in the paper.

Formaldehyde↗
PubMed2005

SPME-GC-pyrolysis-AFS determination of methylmercury in marine fish products by alkaline sample preparation and aqueous phase phenylation derivatization.

Characterization of a cost-efficient analytical method based on alkaline sample digestion with KOH and NaOH, followed by aqueous phase phenylation derivatization with NaBPh4 and solid phase microextraction (SPME) for the determination of methylmercury in typical fish-containing food samples commercially available in Hungary, is reported. The sample preparation procedure along with the applied SPME-GC-pyrolysis-AFS system was validated by measuring certified reference materials (CRM) BCR-464, TORT-2, and a candidate CRM BCR 710. To carry out an estimation of average Hungarian methylmercury exposures via marine fish and/or fish-containing food consumption, 16 commercially available products and 3 pooled representative seafood samples of-according to a previous European survey--the three most consumed fish species in Hungary, herring, sardines, and hake, were analyzed. Methylmercury concentrations of the analyzed samples were in the range 0.016-0.137 microg of MeHg g(-1) dry weight as Hg.

Chromatography, Gas↗
PubMed2001

A new and rapid method for monitoring the new oxazolidinone antibiotic linezolid in serum and urine by high performance liquid chromatography-integrated sample preparation.

A sensitive and rapid HPLC-assay for determining the new oxazolidinone antibiotic linezolid in serum and urine is described. HPLC-integrated sample preparation permits the direct injection of serum and urine samples without any pre-treatment. The in-line extraction technique is realized by switching automatically from the extraction column to the analytical column. After the matrix has passed the extraction column the retained analyte will be quantitatively transferred to the analytical column where separation by isocratic HPLC will be performed. Linezolid is detected according to its absorption maximum at 260 nm. The quantification limits are estimated to be 0.3 and 0.5 microg/ml in serum and urine samples, respectively. The described procedure allows sample clean-up and determination of the antibiotic within 20 min, thereby facilitating drug-monitoring in clinical routine.

Acetamides↗
PubMed2003

A microfluidic electrocapture device in sample preparation for protein analysis by MALDI mass spectrometry.

The design and operation of a microfluidic device for sample preparation in MALDI mass spectrometry of peptides and proteins is described. It is particularly useful for proteomics applications and for mass determination of proteins in salt- and detergent-containing solutions. The system consists of a flow channel with two conductive areas or electrical junctions where proteins and peptides are retained by means of an electric field. The microfluidic device is made of PEEK tubing, and the junctions are covered with a conductive polymeric membrane. A syringe pump connected to the device produces a flow stream, and injection of sample is carried out manually via hydrodynamic pressure. Proteolytic peptides and intact proteins in salt- and detergent-containing acidic media were captured at the cathode junction followed by exchange of the original solution to a solvent suitable for subsequent mass spectrometry. Using this principle, a significant desalting effect was obtained for tryptic peptides in mass-mapping experiments. Protein sequence coverages were high (up to 40%) at subpicomole levels with results better than those obtained using reversed-phase solid-phase extraction. In contrast to the latter technique, the microfluidic device has the capacity to efficiently remove detergents such as CHAPS before peptide mapping and protein analysis.

Animals↗
PubMed1986

A sample preparation for quantitative determination of magnesium in individual lymphocytes by electron probe X-ray microanalysis.

We present a sample preparation method for measuring magnesium in individual whole lymphocytes by electron probe X-ray microanalysis. We use Burkitt's lymphoma cells in culture as the test sample and compare X-ray microanalysis of individual cells with atomic absorption analysis of pooled cell populations. We determine the magnesium peak-to-local continuum X-ray intensity ratio by electron probe X-ray microanalysis and calculate a mean cell magnesium concentration of 39 +/- 19 mmol/kg dry weight from analysis of 100 cells. We determine a mean cell magnesium concentration of 34 +/- 4 mmol/kg dry weight by atomic absorption analysis of pooled cells in three cell cultures. The mean cell magnesium concentrations determined by the two methods are not significantly different. We find a 10% coefficient of variation for both methods of analysis and a 30% coefficient of variation in magnesium concentration among individual cells by electron probe X-ray microanalysis. We wash cells in ammonium nitrate for microanalysis or in buffered saline glucose for atomic absorption analysis. We find cells washed in either solution have the same cell viability (85%), recovery (75%), cell volume (555 microns 3) and cytology. We air dry cells on thin film supports and show by magnesium X-ray mapping that magnesium is within the cells. We conclude that: our microanalysis cell preparation method preserves whole intact lymphocytes; there is no systematic difference in results from the two methods of analysis; electron probe X-ray microanalysis can determine the variation in magnesium concentration among individual cells.

Burkitt Lymphoma↗
PubMed2006

Development of an effective sample preparation approach for proteomic analysis of silkworm eggs using two-dimensional gel electrophoresis and mass spectrometry.

Sample preparation is still the first and important step toward successful two-dimensional gel electrophoresis (2DE) and identification in proteomics study. The 2DE profiling of eggs of silkworm species by using conventional one-step extraction, however, is unsatisfactory because high-abundance proteins such as egg-specific protein (ESP) and No 30 family (30 KP) in the extract lead to difficulties in detecting most of biologically relevant proteins. Based on the tendency of these abundant proteins to be soluble in Tris-HCl buffer, we report herein a robust approach in which the extract enriched in ESP and 30 KP was fractionationed and mixed with the re-extract of residual pellet in an optimal proportion. In comparison with the one-step method, the 2DE pattern was improved by this new method with over one-third enhancement in spots. A total of 48 unique proteins obtained have been furthermore identified by mass spectrometry (MS) and MS/MS. The identified proteins are found to include heat shock proteins families, ribosomal proteins, disulfide isomerase proteins, Glutathione S-transferase, and elongation factor, etc., which are mainly involved in some important processes. To our knowledge, this is the first time that the several proteins have been detected in silkworm eggs by proteomics means. This simple and reproducible approach would raise the opportunity of discovering and identifying more biomarkers and determining their possible roles in further studies.

Animals↗
PubMed1994

Quantitative analysis of a drug in an animal feed employing sample preparation by supercritical fluid extraction.

A pharmaceutical agent has been quantified in a rat feed matrix wherein sample preparation was achieved by supercritical fluid extraction. Spiking levels ranged from 0.0335% to 1.12%. Pure carbon dioxide, solid phase trapping on stainless steel with acetonitrile and liquid chromatographic assay yielded recoveries greater than 90% with relative standard deviations less than 5% in all cases except for the lowest spiking level. In this case recovery was 89.6% with an RSD of 9.6.

Animal Feed↗
PubMedDate not supplied

Applicability of microwave acid digestion to sample preparation of biological materials for analysis by particle-induced X-ray emission (PIXE).

A microwave acid digestion method for the preparation of biological samples for PIXE analysis is presented. The precision and accuracy of the entire PIXE analytical procedure, including the microwave digestion step, were evaluated by analyzing eight certified reference materials. For elements heavier than K, and for concentration levels from 2 micrograms/g upward, the total random error of a single analysis is in the range of 2-5%. The accuracy is better than 5%. The detection limits are down to 0.3 micrograms/g.

Acids↗
PubMed1986

Liquid-solid sample preparation in drug analysis.

This article compares liquid-solid extraction (LSE) with the more conventional liquid-liquid extraction (LLE) for the preparation of biological samples for assay. The commercially available manual LSE methods, Sep-Pak and Bond Elut, as well as the automated instruments Prep and Analytichem Automated Sample Processor (AASP), are reviewed. Using examples from the literature and the authors' own experiences a practical guide is given to the advantages and disadvantages of LSE.

Journal Article↗
PubMed1999

On-line combination of aqueous-sample preparation and capillary gas chromatography.

An overview is presented of methods currently in use to combine the preparation of aqueous samples on-line with capillary gas chromatography. Two approaches can be distinguished: heartcut-orientated reversed-phase liquid chromatography-gas chromatography (GC) and analyte-isolation-orientated analyte extraction-GC. These approaches either use techniques in which water is directly introduced onto the GC column, or an indirect approach in which water is eliminated, i.e., by solid-phase extraction, solid-phase microextraction or liquid-liquid extraction, prior to introduction of the analytes onto the GC column. The latter type of approach is much more successful and user friendly, and many applications have been reported.

Chromatography, Gas↗
PubMed1999

On-line combination of aqueous-sample preparation and capillary gas chromatography.

Methods currently in use to combine the preparation of aqueous samples on-line with capillary gas chromatography (GC) comprise heartcut-orientated reversed-phase liquid chromatography-GC and analyte-isolation-orientated analyte extraction-GC. These approaches either use techniques in which water is directly introduced onto the GC column, or an indirect approach in which water is eliminated, i.e., by solid-phase extraction, solid-phase microextraction or liquid-liquid extraction, prior to introduction of the analytes onto the GC column. The latter type of approach is much more successful and user-friendly, and many applications have been reported.

Chromatography, Gas↗
PubMed2001

Development of a high throughput 96-well plate sample preparation method for the determination of trileptal (oxcarbazepine) and its metabolites in human plasma.

A high throughput preparation method for the determination of trileptal (oxcarbazepine, OXC) and its mono (MHD) and dihydroxy (DHD) metabolites in human plasma, using 96-well plate technology, has been developed and validated according to international regulatory requirements. Preparation of plasma samples (50 microl) containing the compounds to be analysed involved solid-phase extraction (SPE) on Empore C18 96-well SPE plates. Eluates from the plate were injected onto a reversed-phase column (Hypersil C18,3 microm) with UV detection at 210 nm. Detector response was linear over the ranges 0.2-10, 0.1-200 and 0.1-20 micromol/l, for OXC, MHD and DHD, respectively, with relative standard deviations from 1 to 10% and mean accuracies within 4% of the nominal values (number of standard curves=3 in duplicate). The limits of quantitation were 0.2, 0.1 and 0.1 micromol/l, respectively. The overall mean accuracies ranged from 96 to 106% and precision was in the range 4 to 11%. Cross validation indicated no significant difference between plasma concentrations obtained using the 96-well method and the previous method using a traditional SPE method with a 50 mg C18 cartridge. About a threefold increase in sample throughput and a twofold decrease of plasma volume required for the assays, were the main advantages obtained from the previous method. The method was applied for the determination of 3000 plasma samples from clinical studies.

Anticonvulsants↗
PubMed2004

Integrated sample preparation and MALDI mass spectrometry on a microfluidic compact disk.

High-throughput microfluidic processing of protein digests integrated with matrix-assisted laser desorption/ionization (MALDI) mass spectrometry on a compact disk (CD) is described. Centrifugal force moves liquid through multiple microstructures, each containing a 10-nL reversed-phase chromatography column. The CD enables parallel preparation of 96 samples with volumes ranging from one to several microliters. The peptides in the digests are concentrated, desalted, and subsequently eluted from the columns directly into MALDI target areas (200 x 400 microm) on the CD using a solvent containing the MALDI matrix. After crystallization, the CD is inserted into the MALDI instrument for peptide mass fingerprinting and database identification at a routine sensitivity down to the 200-amol level. Detection of proteolytic peptides down to the 50-amol level is demonstrated. The success rate of the CD technology in protein identification is about twice that of the C(18) ZipTips and standard MALDI steel targets. The CDs are operated using robotics to transfer samples and reagents from microcontainers to the processing inlets on the disposable CD and spinning to control the movement of liquid through the microstructures.

Journal Article↗
PubMed1990

Scanning ion microprobe assessment of biological sample preparation techniques.

Different preparation techniques for high lateral resolution scanning ion microprobe imaging of biological samples have been investigated. The sharpest histological maps are obtained from chemically fixed and plastic embedded specimens. It is often problematic to correlate ultrastructure and bioaccumulation from analysis of frozen cut and lyophilized sections. The best compromise is to resin-embed frozen samples in order to get a perfectly flat section from tissue where the in vivo ion distribution is maintained. Use of the University of Chicago Ion Microprobe gave us the ability to observe the relative ion translocations induced during sample preparation. As an example, we show the rapid decrease of intracellular K+/Na+ ratio through a fast frozen blood droplet.

Blood Cells↗
PubMed2002

MALDI-TOF-MS analysis of droplets prepared in an electrodynamic balance: "wall-less" sample preparation.

Methodology enabling mass spectral analysis of the composition of droplet(s) prepared in an electrodynamic balance (EDB) by matrix-assisted laser desorption/ionization (MALDI) is described. The dc field surrounding the electrodynamic balance was manipulated to eject single droplets at a time from the EDB thereby causing their deposition onto a MALDI sample plate precoated with matrix. When the laser was directed onto the droplet(s) and held stationary, marked gains in the signal-to-noise and signal-to-background ratios were realized with each subsequent mass spectrum due to the suppression of matrix cluster ion formation. Optical microscopy of the plate, after 1024 laser shots were fired at eight droplets that had been deposited one on top of the other, revealed a residual island of droplet matter (area approximately 3.1 x 10(-9) m2) inside the region where the crystalline matrix had been ablated away within the laser spot (area approximately 1.6 x 10(-8) m2). Removing the predried crystalline matrix layer and, instead, adding matrix into the starting solution was found to be a more effective means of suppressing matrix cluster ion formation. The chemical composition of the droplet(s) prepared in the EDB is discussed with regard to sample preconcentration, the images of the laser spot after MALDI, matrix cluster ion suppression, and the possibility for improved quantitation and detection limits by MALDI-TOF-MS.

Animals↗
PubMed1989

The influence of blood sample preparation on measured levels of morphine and its major metabolites.

The effect of six different methods of blood sample preparation on concentrations of morphine (M), morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) have been investigated using a specific high performance liquid chromatography assay. No difference between glass or plastic tubes was seen in concentrations of M, M3G, or M6G; and no difference between plasma and serum in M and M6G concentrations. M3G concentrations, however, were significantly lower in plasma compared with serum. Heparin had no effect on M, M6G or M3G, whereas citrate in a glass tube produced consistently lower concentrations of M, M3G and M6G. Standardization of sample collection using plasma samples in plastic heparin tubes is recommended for future studies.

Chromatography, High Pressure Liquid↗
PubMed2005

High sensitivity determination of valproic acid in mouse plasma using semi-automated sample preparation and liquid chromatography with tandem mass spectrometric detection.

A high-throughput liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) assay using automated sample preparation has been developed for the determination of valproic acid (VPA) in mouse plasma. A liquid-handling system was programmed to prepare calibration standard solutions in plasma, as well as quality controls and clinical samples. Plasma protein precipitation was performed on a 96-well plate, and the collected supernatant was directly injected into a reversed-phase LC/ESI-MS/MS system in the negative ionization mode. The calibration curve for VPA was linear over a dynamic range of 0.15-100 microg/mL. The limit of detection was 75 ng/mL and the lower limit of quantitation was 150 ng/mL. Intra- and inter-day validation assays of the semi-automated plasma analysis showed satisfactory accuracy and precision.

Animals↗
PubMed1983

Comparative analysis of meat samples prepared with food chopper and bowl cutter.

Analyses of meat samples after preparation with either a bowl cutter or by the official procedure with a food chopper were compared for homogeneity of comminution and for differences in fat, moisture, and protein content. Cutting time in the bowl cutter was limited to minimize temperature rise in samples. Beef chuck, pork shoulder, and beef shank, cheek, and tongue were used in the study. Variances of replicate analysis data for the 5 meat types were pooled for either cutter or chopper treatment and for each analyzed component. Sample portions cut and mixed by using the bowl cutter were more homogeneous than those ground with a food chopper. Comparative accuracy was indicated by fat and moisture means: 5 were in good agreement and 5 differed significantly; 3 of 5 paired protein means differed significantly but were within 0.3% protein. Results on precision and accuracy as well as the simplicity and convenience of the bowl cutter procedure favor its use as an alternative to a food chopper for preparing meat samples for analysis.

Animals↗