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At least 19 recordsLinked to original sources
PubMed1990

A new comprehensive technique of catheterisation, blood sampling, sample preparation and sample analysis by means of high-pressure liquid chromatography for pharmacokinetic studies with estradiol-linked nitrosoureas and their metabolites.

Estradiol-linked nitrosoureas are offering new perspectives in the antineoplastic chemotherapy of estradiol-receptor positive mammary carcinomas. In such a molecule estradiol has the function of a carrier which brings about a specific accumulation of the anticancer drug in estradiol-receptor containing tumor cells. However, there is only little knowledge about the pharmacokinetic behavior of this new group of anticancer agents. For that reason a new comprehensive technique of catheterisation, blood sampling, sample preparation and sample analysis with high-pressure liquid chromatography (HPLC) for preclinical pharmacokinetic studies with estradiol-linked nitrosoureas and their metabolites has been developed. N-(2-Chloroethyl)-N-nitroso-carbamoyl-L-alanine-estradiol-17-ester (CNC-alanine-estradiol-17-ester) and N-(2-chloroethyl)-N-nitroso-carbamoyl-L-alanine (CNC-alanine) were used as test compounds. The drugs were tested in female Sprague-Dawley rats with chemically induced mammary carcinomas. The laboratory animals were supplied with two catheters prior to the pharmacokinetic experiments. The blood samples were drawn from the vena cava catheter after the drug had been applied through a vena jugularis catheter. The compounds were extracted from plasma with C18 silicagel reversed phase cartridges. The clean-up technique delivered clear samples only slightly contaminated with the biological matrix. The recovery from plasma was 75 +/- 5% for the hormone-linked CNC-alanine-estradiol-17-ester and 70 +/- 5% for the unlinked CNC-alanine. The analysis was carried out by means of HPLC.(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine↗
PubMed1987

A multiple homogenizer for rapid sample preparation in immunoassays and electrophoresis.

A multiple homogenizer is described for preparing samples of small invertebrates or tissue in a flat-bottom immunoplate. Its efficiency was evaluated by immunoassay of carboxylesterase (E4), the enzyme conferring insecticide resistance in the peach potato aphid (Myzus persicae). This equipment was shown to release more enzyme, with less variability, than homogenizing individual aphids and its efficiency allows one person to analyze up to 3000 individual insects per day. It is also suitable for preparing samples for electrophoretic analysis. In the present study samples were loaded onto electrophoresis gels rapidly and accurately by using an eight-channel multipipette.

Animals↗
PubMed1988

Method for evaluating mutagenicity of water. I. A new method of preparing samples for mutagenicity test.

A sample preparation method for a convenient and quantitative mutagenicity test of water was developed using two new superior resinous adsorbents. One, CSP800, is a small particle size and highly porous polystyrene resin, and the other, CHPA25, is a small particle size and highly porous anion-exchange resin. CSP800 adsorbed more nonionic compounds from water than conventional resins, and CHPA25 adsorbed anionic compounds not adsorbed by conventional resins. Sample water (10 l) at pH 5 was fed at 550 ml h-1 into two columns in series, one containing 5 ml of CSP800 and the other 2 ml of CHPA25. The adsorbed substances were subsequently desorbed by DMSO from CSP800 and by 4 N NaNO3 from CHPA25, at 10 ml h-1. Various organic substances, which were measured by different indices such as total trihalomethanes (THM), total organic halogen (TOX) and the absorbence at 260 nm, could be recovered by this method much more efficiently and conveniently than by conventional methods.

Chromatography, Ion Exchange↗
PubMed1989

[Use of electroblotting as a method for preparing samples of proteins and their fragments for microsequencing].

Gel electrophoresis in the presence of sodium dodecyl sulphate followed by electroblotting was employed in sample preparation for microsequencing proteins and protein fragments. Three types of solid supports were compared: glass fiber filters modified by aminopropyltriethoxysilane or covered with polybrene, and polyvinylidenedifluoride membranes. N-Terminal amino acid sequences of several proteins (Mr 14-140 kDA were determined on a gas-phase sequencer with the standard programme; 20-200 pmoles of the protein can be assayed by this method.

Adenylyl Cyclases↗
PubMed1992

Improved sample preparation for the testosterone hydroxylation assay using disposable extraction columns.

The preparation of samples for injection into a high-performance liquid chromatograph from assay mixtures for the determination of cytochrome P-450-dependent testosterone hydroxylation has been substantially facilitated. By replacing the multiple cumbersome extraction steps of the conventional method with a single column extraction the time for sample preparation was reduced from hours to minutes. The new procedure also yields better recoveries for most of the testosterone metabolites than the original protocol. The use of extraction columns for sample preparation allows the simultaneous treatment of a large number of samples or even the automation of the whole assay procedure. The modified procedure is a straightforward, easy-to-perform method that should greatly facilitate the implementation of the testosterone hydroxylation assay for sharply discriminating between many individual cytochrome P-450 species in routine enzyme diagnostics.

Chromatography↗
PubMed1989

Sample preparation for biomedical analysis.

A review of sample preparation techniques for biomedical analysis is presented. Firstly, sample preparation techniques can be divided into unit operations which can be classified into four groups: release of the analyte from the matrix, removal of endogenous material, liquid handling procedures and the enhancement of selectivity and sensitivity. The concept of unit operations gives an analyst a tool with which to evaluate critically any method for preparing a sample for analysis. Secondly, the major techniques of sample preparation (protein precipitation, liquid-liquid extraction, liquid-solid extraction and high-performance liquid chromatography, HPLC) are discussed and their advantages and disadvantages presented. Thirdly, the rationale for the automation of sample preparation is reviewed; in general liquid-solid extraction and HPLC are the best techniques for automation. The means by which this can be effected (either flexible or dedicated automation) is discussed. Finally, techniques such as supercritical fluid extraction, micellar liquid chromatography, microwave energy and immunoextraction which may be applied to biomedical sample preparation are evaluated briefly.

Chemistry Techniques, Analytical↗
PubMed2024

ZASP: A Highly Compatible and Sensitive ZnCl2 Precipitation-Assisted Sample Preparation Method for Proteomic Analysis.

Universal sample preparation for proteomic analysis that enables unbiased protein manipulation, flexible reagent use, and low protein loss is required to ensure the highest sensitivity of downstream liquid chromatography-mass spectrometry (LC-MS) analysis. To address these needs, we developed a ZnCl2 precipitation-assisted sample preparation method (ZASP) that depletes harsh detergents and impurities in protein solutions prior to trypsin digestion via 10 min of ZnCl2 and methanol-induced protein precipitation at room temperature (RT). ZASP can remove trypsin digestion and LC-MS incompatible detergents such as SDS, Triton X-100, and urea at high concentrations in solution and unbiasedly recover proteins independent of the amount of protein input. We demonstrated the sensitivity and reproducibility of ZASP in an analysis of samples with 1 μg to 1000 μg of proteins. Compared to commonly used sample preparation methods such as SDC-based in-solution digestion, acetone precipitation, FASP, and SP3, ZASP has proven to be an efficient approach. Here, we present ZASP, a practical, robust, and cost-effective proteomic sample preparation method that can be applied to profile different types of samples.

Proteomics↗
PubMedDate not supplied

An evaluation of sample preparation techniques for the GC/MS analysis of urinary mercapturic acid conjugates.

Recovery rates of four different techniques for the preparation of human urine samples spiked with N-acetyl-S-benzyl-L-cysteine (BMA) were compared at three different spiking levels. At concentrations of 1,000 ppm and 1 ppm in the urine, recoveries of BMA were greatest (80-96%) using an ion pair phase transfer technique and a C18 solid-phase extraction (C18) technique while an acidic ethyl acetate extraction method yielded 67-69% recoveries and a quaternary amine solid-phase extraction technique showed poor recoveries (5-7%). At 10 ppb, quantitative recovery could only be determined for the C18 technique due to interferences from samples prepared using the other three techniques. The results indicate that the C18 sample preparation technique followed by GC/MS analysis using stable isotopically labeled internal standards provides a rapid and accurate method for quantitation of mercapturic acids at low-ppb levels in the urine.

Acetylcysteine↗
PubMed1990

On-line combination of dialysis and column-switching liquid chromatography as a fully automated sample preparation technique for biological samples. Determination of nitrofuran residues in edible products.

The potential of dialysis coupled on-line with trace enrichment by column-switching high-performance liquid chromatography as an automated sample treatment technique in drug residue analysis has been investigated. The nitrofuran veterinary drugs furazolidone, nitrofurazone, nitrofurantoin and furaltadone were used as model compounds. Critical parameters, i.e., dialyser dimensions, air segmentation, dialysis time, flow-rates and enrichment column breakthrough, were evaluated. Depending on the analytical purpose, the technique can be set up in either a highly sensitive or a high-speed mode. High dialysis efficiencies (greater than 85%) can be obtained in a stopped-flow dialysis of only 3 min. Aqueous biological sample volumes (eggs, meat, milk) of 100 microliters to 4 ml can be injected with only sample treatment. A routine monitoring method for residues of nitrofuran drugs in edible products was set up. A 4-ml sample was dialysed in a pulsed mode with an efficiency of about 30% and concentrated on a short C18 column. Recoveries compared with standards were 75-85% (coefficient of variation 2-7%). Limits of determination ranged from 1 to 10 micrograms/kg. At this concentration level, ca. 30 samples can be monitored per day.

Animals↗
PubMed1989

A variation of transmission electron microscope sample preparation for VLSI analysis.

Sample preparation for VLSI analysis is often slow due to long ion milling time and because the location of the thin area of the sample is difficult to control. By modifying the standard techniques used with a VCR Group (and perhaps other) mechanical dimpler, the ion milling time can be reduced to less than 30 min. and the location on the thinned area reasonably controlled. These modifications involve the use of a radiused edge on the dimpling tool, a rubber O-ring on the polishing tool, and not rotating the sample platen during polishing. The modifications to the dimpling and polishing tools allow more control of the geometry of the dimple, while not rotating the sample platen allows a thinner sample to be produced and permits the use of the sample translation micrometers to shift the location of the thinned area during polishing. The quality of samples produced using this modified procedure is equivalent to that obtained with the more standard methods.

Metals↗
PubMedDate not supplied

Sample preparation variation and its effects on automated blood cell differential analysis.

Uniform and reproducible sample preparation is an indispensable ingredient in automated instruments for cell analysis. Differences in measured cell morphology resulting from nonuniform sample preparation are indistinguishable to the instrument from differences reflecting different cell types or functions. As a result, as sample preparation becomes more variable, subtle cell distinctions are first confused and then completely obscured. As part of the development of the Abbott ADC-500 differential analysis system, automatic blood film spinner and stainer modules were developed to provide uniform sample preparation. These modules were tested to quantitate the effects of variations in the spinning and staining conditions on the measured ADC-500 parameters and observed cell morphology. The previously reported increase in spin time with increasing hematocrits was confirmed for the ADC-500 spinner. Moderate variations in spin speed, acceleration, deceleration and spin chamber configuration were found to have little or not effect. Postspinning air flow over the slide had a dramatic effect on morphology distortion. Variations of the staining temperature, staining time or rinse volume were found to have very little effect on measured leukocyte parameters although staining temperature had a dramatic effect on observed erythrocyte morphology and staining. Stain:buffer ratio variations were found to alter measured leukocyte parameters, with the measured density increasing as the fraction of stain increased up to a 1:2 stain:buffer ratio. Because the operational limits for the spinning and staining parameters are much tighter than the range of variables investigated, it was concluded that the ADC-500 sample preparation modules do not introduce variations in the analyzer results.

Autoanalysis↗
PubMed1989

Sample preparation for the HPLC analysis of drugs in biological fluids.

Sample preparation for the analysis of drugs in biological fluids consists of a number of unit operations that are used for (i) release of the drug from a conjugate or biological matrix; (ii) removal of endogenous compounds that could interfere with the assay; and (iii) techniques for liquid handling. The trends in sample preparation that have occurred over the past 10 years in the authors' laboratory are discussed. In general, there has been a move from the traditional liquid-liquid extraction to methods using bonded-silica which permit rapid throughput and efficient extraction. Automation of sample preparation has seen further gains in productivity; however, the present generation of equipment lack the control and communication systems that are essential for the development of the automated integrated laboratory of the future.

Automation↗
PubMed1990

[The use of the ion exchange polymer Wofatit CP for sample preparation of drugs from urine for high pressure liquid chromatographic and spectrophotometric determinations].

The sample preparation of the alkaline drugs dioxopromethazinehydrochloride and trapidil from urine was studied systematically. The weak acid cation exchanger Wofatit CP was used as stationary phase. Batch mode and column chromatographic sample preparation were compared. The usable capacity of the ion exchanger for the analyte is an important characteristic for the sample preparation. The great influence of pH and ionic strength of the sample on the usable capacity was proved.

Acrylic Resins↗
PubMed1988

Rapid sample preparation for determination of iron in tissue by closed-vessel digestion and microwave energy.

We developed a rapid acid-digestion method for preparing tissue samples for iron determination. Specimens were digested in nitric acid and hydrogen peroxide under high temperature and pressure in closed Teflon vessels, with microwave energy. Analysis for iron in 25- to 250-mg portions of digested bovine liver powder (National Bureau of Standards Certified Reference Material no. 1577a) showed excellent linearity ([predicted] = 1.007[actual] - 0.166 micrograms per sample) and analytical recovery (98%). Precision (CV) was 5.4% when iron content was 10 micrograms per sample. Assaying split samples of mouse tissues, we found a close correlation between iron concentrations obtained with closed vs open vessels ([closed] = 0.878[open] + 68 micrograms/g, r = 0.994, range 400-4600 micrograms/g dry weight). In contrast to time-consuming conventional procedures for tissue dissolution, closed-vessel digestion with microwave energy dramatically shortens time for tissue preparation, minimizes use of caustic acid, reduces risk of sample loss or contamination, and yields accurate and reproducible results.

Animals↗
PubMed1987

Degradation artefacts during sample preparation for sodium dodecyl sulphate polyacrylamide gel electrophoresis.

Preparation of samples for sodium dodecyl sulphate polyacrylamide gel electrophoresis routinely involves heating the protein in solution containing detergent and reducing agent for at least two minutes. Here we show that this treatment causes fragmentation of the protein glycogen phosphorylase, whether purified or as a component of a skeletal muscle preparation. The fragments are detected as minor bands on western blots and represent the products of discrete breakage point in the peptide sequence. Protease inhibitors cannot suppress the fragmentation. Such small amounts of immunoreactive fragments may be incorrectly identified on western blots as contaminants that were originally present in the antigen preparation. They may also be a source of ambiguity in studies that search for degradation intermediates during proteolysis.

Animals↗
PubMedDate not supplied

Sampling and sample preparation for detection and quantitation of natural toxicants in food and feed.

The primary goal of a sampling plan for natural toxins, i.e., mycotoxins and seafood toxins, is to obtain a sample that accurately represents the concentrations of individual components of a given lot. Factors affecting the ability of the sampling plan to accomplish this goal include: (1) nature of the analyte of interest; (2) distribution of the analyte throughout the lot, (3) physical characteristics of the product, (4) accessibility of the product to random representative sampling, (5) sampling procedure, and (6) size of sample. Sampling plans are composed of 3 distinct components: (a) sampling, (b) sample preparation, and (c) analysis. Normally, sampling contributes the largest relative error while analysis comprises the least. Automatic, continuous stream samplers provide the most representative samples for commodities such as nuts, cottonseed, and cereal grains. Good sample preparation equipment is currently available for these commodities; the use of this equipment to obtain a representative test sample is discussed.

Animal Feed↗
PubMed1992

Sample preparation for chromatographic analysis of food.

Sampling, homogenisation and sample preparation prior to chromatographic injection of food analytes are designed to enhance accuracy and precision. The reduction of inherent errors introduced by these steps requires the analyst's attention as a matter of course. Methods and examples of minimising errors in each step are reviewed.

Chromatography↗