共查询到20条相似文献,搜索用时 15 毫秒
1.
The effect of silica gel on the recovery of radioactivity from 14C- and 3H-labeled lipids by liquid scintillation is analyzed. In the most unfavorable ease, when counting with a toluenefluor solution directly added to the vials containing the adserbed lipid, drastic reductions in the counting efficiency were found, which depended on the amount of silica gel, sample activity, and chemical nature of the lipid. For certain lipids like phosphatidylcholine, these effects were not completely overcome even by introducing water and detergents in the counting system. This paper intends to draw attention to the fact that these factors should be especially taken into account when comparing different lipids from thin-layer chromatograms. 相似文献
2.
A procedure which combines thin-layer chromatography with position-sensing proportional counting has been developed for analyzing the metabolism of carcinogenic polycyclic aromatic hydrocarbons. The profiles of the metabolites of [3H]benzo(a)pyrene and 7,12-[12-14C]dimethylbenz(a)anthracene produced in cell culture were comparable when obtained by this procedure and by standard methods. However, position-sensing proportional counting allows simultaneous counting of all components of a sample within 10–20 min, and thereby permits the analysis of many hydrocarbon samples in a short time. In addition, the procedure eliminates the necessity of cutting or scraping carcinogen-containing thin-layer chromatograms. 相似文献
3.
Summary A procedure for counting p32 in plant tissues is presented. The method, based on the use of Cerenkov radiation, involves practically no sample preparation.
Plant tissue are placed into vials containing water or hexane and counted with a liquid scintillation counter.
Counts obtained, using this procedure were found to be linearily related to that obtained with a G.M. tube. The counting efficiency
was, however, higher with the proposed method.
The use of hexane is advantageous if leakage of p32 from the tissue is possible, or when higher counting efficiency is desireable. The use of different liquids may also enable
a discriminative count of different beta emitters. As suggested recently8 use of wavelength shifter may further increase efficiency of counting Cerenkov radiation. 相似文献
4.
Emma Villa-Moruzzi Teresa Locci-Cubeddu Ettore Bergamini 《Analytical biochemistry》1979,100(2):371-372
As an alternative to rapid filtration washing the glycogen free of any unreacted UDP-[14C]-glucose by ascending chromatography (ethanol:water, 2:1) can be used. This technique also makes the filter paper assay of glycogen synthase much faster: The samples are ready for liquid scintillation counting in 30 min. Among the other advantages offered by this procedure, we should also mention that blanks are very low, large volumes of ethanol can be saved, and the unreacted UDP-[14C]glucose can be recovered by elution and recycled (it migrates with the front of the solvent). 相似文献
5.
Jorma Viikari 《Analytical biochemistry》1975,63(2):566-571
A rapid and simple method for counting radioactivity in tissue samples containing [3H]- or [14C]-cholesterol is described.Up to 500 μl of the specimen to be counted (plasma, tissue homogenate) is measured into a counting vial. The lipids of the tissue are extracted into 15 ml of a toluene-based scintillation mixture containing 37.5% ethylene glycol monomethyl ether that is added to the same vial. With the addition of 1 ml water, two phases form: the upper toluene phase containing all cholesterol together with the scintillating phosphor and the lower water phase containing most of the quenching material. Bleaching to reduce color quenching is not necessary. Chemiluminescence is negligible. The counting efficiencies are appreciably higher than those obtained in aqueous one-phase scintillation systems but lower than those obtained with pure standards in one-phase pure toluene scintillation systems. 相似文献
6.
L Hunter 《Analytical biochemistry》1978,89(1):279-283
A simple, economical method for counting acrylamide gel slices on solid filter paper supports in a toluene-based scintillation cocktail is described. Major advantages of the system include no requirement for either dissolution of the gel or elution of the radioactive material prior to emulsion counting and the direct reutilization of scintillation cocktail and vials. Additionally, 32P-labeled RNA samples can be counted with better relative efficiencies and those labeled with 14C or 33P can be determined at equivalent efficiencies. Tritium was detected less readily, with an absolute efficiency of approximately 10%. 相似文献
7.
Improvements in and Environmental Applications of Double-Vial Radiorespirometry for the Study of Microbial Mineralization 总被引:4,自引:3,他引:1
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Several variations in the scintillation mixture and the filter paper arrangements for double-vial radiorespirometry were compared. Improved efficiencies (44%) and shorter response times were found by adding wetting agents and methanolic NaOH to the scintillation mixture in the filter paper. The scintillation chemicals used did not contain dioxane and were found to be nontoxic to the test microbiota in this system. Covering the inner reaction vial with aluminum foil minimized the reduction in counting efficiency when testing colored or dense environmental samples. Mineralization rates were determined with 14C-labeled glucose, acetate, and glutamate and [14C]cellulose- and [14C]lignin-labeled lignocellulose for composting cow manure, forest soil, and arctic lake sediment microbiota. This improved method can be used in a variety of procedures involving the measurement of microbial mineralizations of organic compounds. Since no liquid scintillation cocktail is used for counting, the radioactive wastes are aqueous or can be incinerated, making disposal easy. 相似文献
8.
High-efficiency liquid-scintillation counting of 14C-labelled material in aqueous solution and determination of specific activity of labelled proteins 总被引:17,自引:17,他引:0
1. Inexpensive scintillation mixtures are described which enable the detection of as little as 40μμc of 14C in aqueous solution with an efficiency of counting of over 80%. 2. A rapid method for the counting of alkaline, acidic and neutral aqueous solutions of up to 1ml. volume is described. Ethanol or 2-ethoxyethanol is used as blending agent. 3. The scintillation counting of alkaline solutions is applied to the accurate determination of the specific activity of 14C-labelled proteins from plant tissues. 4. Attention has been paid to the importance of a standardized washing procedure for the removal of all traces of radioactive material from glassware. 相似文献
9.
[14C]polyethylene glycol is the method of choice for quantitating changes in intestinal water flux during drug absorption experiments in animals and man. This study points out some of the problems which can be encountered in using this method and provides ways to minimize these problems. Polyethylene glycol selectively binds to the glass wall of scintillation vials during counting and results in a decrease in counting efficiency as a function of time. The results obtained when using this method are determined by the choice of scintillation vial, scintillation cocktail, concentration of polyethylene glycol and the time period over which the samples are counted. 相似文献
10.
An improved scintillation cocktail of high-solubilizing power 总被引:55,自引:0,他引:55
A scintillation cocktail containing 25% Triton X-114 in xylene is considered for a broad range of scintillation counting applications. The cocktail gives good counting efficiencies for 3H (47%) and 14C (93%). It will accept up to 30% (v/v) aqueous sample. The scintillation fluid is also used effectively with samples which are difficult to solubilize, such as the degradation products from the solubilization of polyacrylamide gels. The cocktail can be formulated for less than $2.00 per gallon. 相似文献
11.
A rapid procedure is described for the liquid scintillation counting of 14C-labeled hemin isolated after incubation of bone marrow with radioactively labeled glycine-2-14C. The method has been applied for studies on the biosynthesis of heme in bone marrow of several animal species. 相似文献
12.
Measurement of 131 I and 125 I by liquid scintillation counting 总被引:1,自引:0,他引:1
When aqueous samples are made miscible with a toluene scintillation solution by means of Bio-Solv BBS-3, high 125I and 131I efficiencies can be achieved over a considerable range of “impurity” quenching, and adequate isotope separations can be achieved using liquid scintillation counters with “linear,” “pseudologarithmic,” or “logarithmic” amplification. Using an example of each sort of counter, we have graphically outlined the two somewhat different procedures for choosing the best instrument settings for single- and double-isotope counting. “Linear” instruments, despite a slightly more complex procedure for selection of settings, may offer the advantage, in double-isotope counting, of somewhat greater isotope separations because of the greater attenuation of photo-electron spectra. 相似文献
13.
W L Hughes 《Analytical biochemistry》1987,161(2):529-532
The entire procedure is carried out in a counting vial by mixing the reagents as a 20- to 30-microliters drop in the cap of a counting vial, incubating, quenching the reaction, and then distilling the tritium water produced into the chilled vial, in which it is assayed after the addition of scintillation solvent and a clean cap. The application of this technique to the analysis of serum transaminases is described. 相似文献
14.
Picogram quantities of the catecholamines, dopamine, norepinephrine, and epinephrine, and the dopamine metabolite, dihydroxyphenylacetic acid, can be measured in tissue or plasma samples utilizing a rapid radioenzymatic procedure. The catechols are converted to their 3H-methylated derivatives (3-methoxytyramine, normetanephrine, metanephrine and homovanillic acid, respectively) by the enzyme catechol-O-methyltransferase with 3H-S-adenosylmethionine serving as the 3H-methyl donor. Following the enzymatic reaction, unreacted 3H-S-Adenosylmethionine is removed by precipitation and the reaction products are separated by thin layer chromatography on silica plates. The areas corresponding to the 3H-methylated derivatives are scraped into scintillation vials, eluted with aqueous buffer, extracted into nonpolar scintillation cocktail, and counted by liquid scintillation spectrometry. Using the standard assay procedure described here, over 100 tubes can be assayed in a single day with a sensitivity of 15–25 pg for all compounds measured. With the application of additional procedures, as little as 1 pg norepinephrine and epinephrine and 5–10 pg dopamine and dihydroxyphenylacetic acid can be quantified in a single sample. 相似文献
15.
B. -M. Eriksson L. Tekenbergs 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1981,223(2):401-408
A liquid chromatographic method for the determination of digoxin, digoxigenin, its mono- and bisdigitoxoside and dihydrodigoxin in urine is described. Doses of 100 μCi of [12α-3H] digoxin and 0.5 mg (640 nmol) of digoxin were administered orally to eight healthy volunteers. The compounds were extracted from urine with methylene chloride containing 3% of heptafluorobutanol. After separation, fractions corresponding to digoxin and the metabolites were measured by liquid scintillation counting. Conjugates of the glycoside metabolites were determined indirectly after pre-treatment of the samples with β-glucuronidase—arylsulphatase. The detection limit was 0.1 nmol/l. Metabolites amounting to 0.5% of digoxin were assayed with a relative standard deviation of 5%.The advantages of the method are a high recovery in the extraction step, short separation times and the possibility of separate assay of dihydrodigoxin. 相似文献
16.
The counting rate of [1-14C]trichloroacetic acid (TCA) was not stable in a standard toluene/Triton X-100 liquid scintillation solution because this compound becomes partially degraded to 14CO2 and CHCl3. Both toluene and Triton were contributing factors in causing this degradation. The NCS solubilizer added to the toluene/Triton scintillation solution trapped 14CO2 and stabilized counting rates of [1-14C]TCA. When [2-14C]TCA was used, 14CHCl3 remained in the scintillation solution resulting in stable counting rates without the addition of NCS. 相似文献
17.
Soil saccharide extraction and detection 总被引:6,自引:0,他引:6
Extraction of soil saccharides involves the use of reagents effective in breaking hydrogen and covalent bonds between soil
constituents and the saccharides. Of the many extractants proposed for saccharide determination, water is commonly used for
extraction of water-soluble mono- and polysaccharides in soil. Analysis of these water extracts by colorimetric assays (anthrone-sulfuric
acid and phenol-sulfuric acid methods) often show color development indicating that saccharides are present. However, high
performance liquid chromatography (HPLC) and gas chromatography analyses have indicated that these colorimetric assays are
prone to errors due to interferences from inorganic soil constituents such as Cl−, NO3
− and Fe+3. When water extracts (25° or 80°C) are put through deionization resins to remove interferences little to no saccharides are
present when assayed by the phenol-sulfuric acid analysis. The inability of water to extract saccharides from soil or microbial
polymers was confirmed by HPLC analysis. The phenol-sulfuric acid assay was found to be acceptable for saccharide analysis
of soil extracts only after being subjected to resin deionization for interference removal. The anthrone-sulfuric acid method
is not considered acceptable for determining saccharides in soil. 相似文献
18.
We report a new quantitative proteomics approach that combines the best aspects of stable isotope labeling of amino acids in cell culture (SILAC) labeling and spectral counting. The SILAC peptide count ratio analysis (SPeCtRA, http://proteomics.mcw.edu/visualize ) method relies on MS2 spectra rather than ion chromatograms for quantitation and therefore does not require the use of high mass accuracy mass spectrometers. The inclusion of a stable isotope label allows the samples to be combined before sample preparation and analysis, thus avoiding many of the sources of variability that can plague spectral counting. To validate the SPeCtRA method, we have analyzed samples constructed with known ratios of protein abundance. Finally, we used SPeCtRA to compare endothelial cell protein abundances between high (20 mM) and low (11 mM) glucose culture conditions. Our results demonstrate that SPeCtRA is a protein quantification technique that is accurate and sensitive as well as easy to automate and apply to high‐throughput analysis of complex biological samples. 相似文献
19.
Following a 10 min pulse labeling with 3H-TdR, flasks of asynchronous monolayer cultures of Chinese hamster ovary cells were subjected to mitotic selection at 2 hr intervals. The mitotic index of the selected populations was always greater than 90%. Counts per min per cell obtained by liquid scintillation counting were plotted versus time after the pulse label. Comparisons were made between cycle times obtained by the mitotic-scintillation counting method and by the standard per cent labeled mitosis technique. The resulting curves were used for calculations of the cell cycle times and the lengths of G1, S, G2 and M phases of the cell cycle. There was less than 2% difference in the cell cycle times obtained using the scintillation method as compared to times calculated from autoradiographic data obtained from individual petri dishes. The mitotic-scintillation counting technique is simple, accurate and rapid and allows the calculation of the cell kinetics parameters within 1 hr of the end of the experiment. 相似文献
20.
Determination of levels of glycolytic intermediates and nucleotides in platelets by pulse-labeling with [32P]orthophosphate 总被引:1,自引:0,他引:1
Holm Holmsen Carol A. Dangelmaier Jan-Willem N. Akkerman 《Analytical biochemistry》1983,131(1):266-272
A method is presented for the separation and quantification of 32P-labeled carbohydrates and nucleotides in blood platelets which have been pulse-labeled with [32P]orthophosphate. The procedure is based on two-dimensional paper chromatography, identification of the spots by radioautography and enzymatic methods, and quantitation of 32P radioactivity by liquid scintillation counting. The data show that 32P is homogeneously distributed among the compounds studied so that the total radioactivity is proportional to the levels of these compounds in the metabolic compartment of the cells. Thus, this method provides a sensitive and accurate means to evaluate phosphorylated intermediates in glycolysis and nucleotide metabolism and to assess the transfer of energy-rich phosphate groups between these pathways in particular. 相似文献