Showing papers on "Reagent published in 1982"
TL;DR: In this direct colorimetric procedure, serum triglycerides are hydrolyzed by lipase, and the released glycerol is assayed in a reaction catalyzed by glycersol kinase and L-alpha-glycerol-phosphate oxidase in a system that generates hydrogen peroxide.
Abstract: In this direct colorimetric procedure, serum triglycerides are hydrolyzed by lipase, and the released glycerol is assayed in a reaction catalyzed by glycerol kinase and L-alpha-glycerol-phosphate oxidase in a system that generates hydrogen peroxide. The hydrogen peroxide is monitored in the presence of horseradish peroxidase with 3,5-dichloro-2-hydroxybenzenesulfonic acid/4-aminophenazone as the chromogenic system. The high absorbance of this chromogen system at 510 nm affords useful results with a sample/reagent volume ratio as low as 1:150, and a blank sample measurement is not needed. A single, stable working reagent is used; the reaction is complete in 15 min at room temperature. The standard curve is linear for triglyceride concentrations as great as 13.6 mmol/L. Average analytical recovery of triglycerides in human sera is 100.1%, and within-run and between-run precision studies showed CVs of less than or equal to 1.6 and less than or equal to 3.0%, respectively. The method is suitable for automation.
2,758 citations
TL;DR: A new solid-state reagent for iodinating polypeptides and proteins was used to radiolabel antiporcine insulin antiserum which retained its immunological ability to recognize insulin.
853 citations
TL;DR: A new colorimetric technique for the estimation of ascorbic acid by using Folin phenol reagent has been developed and has been found to be stable up to 18 h and almost 100% efficient.
475 citations
267 citations
TL;DR: A single labelled peptide was purified from the inhibited ATPase and it was shown that Lys 3/190, 10 residues from the N‐terminus of tryptic fragment B, was the reactive lysine residue, close to a potential nucleotide‐binding fold in the ATPase sequence.
242 citations
TL;DR: Results of experiments with the penetrating sulfhydryl reagent, N-ethyl maleimide (NEM), and the impermeant reagent , p-chloromercuribenzene sulfonic acid (PCMBS), indicated that the saturable and linear components were independent mechanisms of K(+) transport.
Abstract: Influx isotherms were obtained for 86 Rb + uptake into 2-cm corn ( Zea mays [A632 × (C3640 × Oh43)] root segments for both low- (0.2 millimolar CaSO 4 ) and high-salt (0.2 millimolar CaSO 4 + 5 millimolar KCl) grown roots. Unlike the discontinuous curves usually presented for K + influx, our isotherms were smooth, nonsaturating curves that approached linearity at K + (Rb + ) concentrations above 1 millimolar. The kinetics for K + transport could be resolved into saturable and linear components. The saturable components yielded K m values of 16 and 86 micromolar for low- and high-salt roots, respectively, while V max values were 5.62 and 1.85 moles per gram fresh weight per hour. Results of experiments with the penetrating sulfhydryl reagent, N -ethyl maleimide (NEM), and the impermeant reagent, p -chloromercuribenzene sulfonic acid (PCMBS) indicated that the saturable and linear components were independent mechanisms of K + transport. Short-term NEM exposures (30 seconds to 5 minutes) selectively inhibited the saturable system, but had little effect on the linear component. Increasing NEM exposures resulted in further inhibition and subsequent abolition of the saturable component; the linear component exhibited limited NEM sensitivity. PCMBS elicited the same general inhibitory trends, although it was less effective as a saturable component inhibitor. The effects of NEM and PCMBS on K + efflux were also studied. Short NEM exposures had no effect on cytoplasmic efflux, while inhibiting vacuolar efflux significantly. From these data, it is unclear at which site(s) NEM is acting. A more complex response was obtained with PCMBS, where a monophasic efflux curve was observed. Analysis indicated that the vacuolar efflux was stimulated, while the cytoplasmic component was abolished. The nature of the linear component is discussed, and it is proposed that the mechanism may be more complex than simple facilitated diffusion.
220 citations
TL;DR: A new approach for the reaction of Sepharose with cyanogen bromide is described, using triethylamine as a “cyano-transfer” reagent, and an optimized procedure for activation at neutral pH was developed.
210 citations
TL;DR: In this paper, an alternative mechanism involving dioxiranes as the reactive species was proposed, which is relevant to catalytic oxidations using O2, H2O2 or ROOH.
Abstract: In this progress report an attempt is made to rationalize, from a mechanistic point of view, the different ways in which oxygen is transferred from inorganic and organic peroxides to nucleophilic substrates, particularly olefins. Oxygen transfer from transition-metal peroxides, which is relevant to catalytic oxidations using O2, H2O2 or ROOH, occurs via a cyclic or “pseudocyclic” peroxymetalation in which a dioxametallacycle is formed. Owing to the wide discrepancy between peroxymetalation and the conventional oxidation mechanism, i.e. nucleophilic attack of the substrate at the electrophilic “active oxygen”, we propose an alternative mechanism involving dioxiranes as the reactive species. The generation of dioxiranes appears to be a common denominator in the reactions of most organic peroxides e.g. peroxy acids, the reaction of electrophilic ketones with H2O2, or ozonizations. Oxygen transfer from dioxirane reagents probably involves the formation of a charge-transfer π-complex between the substrate and the carbon atom of the dioxirane, and the subsequent formation of a cyclic peroxidic intermediate.
199 citations
TL;DR: Addition of sodium dodecyl sulfate to the reagent equalizes the reactivity for human albumin, transferrin, IgG, thus making its use for cerebrospinal fluid protein assay valid.
167 citations
TL;DR: In this article, a synthesis of tris(trimethylsilyl)silyllithium · 3 THF is described, which can be used in hydrocarbon solvents to give improved yields of coupling products.
166 citations
TL;DR: In this paper, a model of diffusion controlled mass transfer in liquid surfactant membranes is developed for uniform emulsion globules having no internal circulation, where the solute is assumed to react instantaneously and irreversibly with the internal reagent at a reaction surface which advances into the globule as the reagent is consumed.
Abstract: A model of diffusion controlled mass transfer in liquid surfactant membranes is developed for uniform emulsion globules having no internal circulation. The solute is assumed to react instantaneously and irreversibly with the internal reagent at a reaction surface which advances into the globule as the reagent is consumed. A perturbation solution to the resulting non-linear equations is presented. In general, the zero-order, or pseudo-steady state solution alone often gives an adequate representation of the process. Experimental data on the batch extraction of phenol from waste water are in good agreement with the model predictions.
TL;DR: A low valent chromium reagent is generated from chromium(III) chloride and a half mol of lithium aluminum hydride in tetrahydrofuran as mentioned in this paper, which behaves similarly to anhydrous chromium (II) chloride, which is commercially available, and reduces allylic halides to produce unisolable allylchromium species which add efficiently to aldehydes or ketones with high degree of stereo and chemoselectivity.
Abstract: A low valent chromium reagent is generated from chromium(III) chloride and a half mol of lithium aluminum hydride in tetrahydrofuran. The reagent behaves similarly to anhydrous chromium(II) chloride, which is commercially available, and reduces allylic halides to produce unisolable allylchromium species which add efficiently to aldehydes or ketones with high degree of stereo- and chemoselectivity. Particularly, high threo selectivity is observed in the reaction of aldehydes and 1-bromo-2-butene and is ascribed to a chair-like six-membered transition state. Simple reduction of allylic and benzylic halides produces biallyls and bibenzyls, while gem-dibromocyclopropanes afford the corresponding allenes in excellent yields.
TL;DR: In this paper, the synthesis, characterization, and application of N-(trimethoxysilyl-propyl)pyrrole (I) as a photoanode derivatizing reagent that can be covalently anchored to the electrode via reaction of surface OH groups are described.
Abstract: The synthesis, characterization, and application of N-(3-(trimethoxysilyl-propyl)pyrrole (I) as a photoanode derivatizing reagent that can be covalently anchored to the electrode via reaction of surface OH groups are described. The pendant group of I can then be used as the initiation site for polymerization of polypyrrole. The treatment of both Pt and n-type Si electrodes with I and films of polypyrrole to protect the semiconductor from photoanodic decomposition is described. Improved durability noted for the treated n-type Si electrodes is attributed to less H/sub 2/O/electrolyte undermining of the polymer when it is covalently anchored to the surface. (BLM)
TL;DR: The action of lithium diisopropylamide on diethyl difluoromethylphosphonate gives the title reagent which reacts with various electrophiles to introduce Difluorsomethylene or diffluoromethsyl unit as mentioned in this paper.
Patent•
04 May 1982
TL;DR: In this article, an assay method and compositions are provided for determining the presence of an analyte in a sample, where the analyte is a member of an immunological pair (mip) comprising ligand and receptor.
Abstract: An assay method and compositions are provided for determining the presence of an analyte in a sample. The analyte is a member of an immunological pair (mip) comprising ligand and receptor. By providing a first measurement surface capable of specifically binding a labelled reagent in an amount depending upon the presence of analyte in the sample and a second calibration surface capable of binding a second labeled reagent in a manner unaffected by the presence of analyte in the sample, calibration of individual tests can be accomplished simulataneously with the performance of the test itself. A signal producing system includes an enzyme bonded to a mip which defines the first labeled reagent for binding to the measurement surface and the same enzyme conjugated to a ligand capable of binding to the calibration surface. Preferably, both labeled reagents have the same composition and the calibration surface includes anti-(first enzyme).
TL;DR: In this article, the effectiveness of metal fluorides impregnated on alumina as a reagent for promoting alkylation was optimized with respect to the metal cation, the amount of impregnation, and the reaction solvent.
Abstract: The effectiveness of alkali metal fluorides impregnated on alumina as a reagent for promoting alkylation was optimized with respect to the metal cation, the amount of impregnation, and the reaction solvent. Potassium or caesium fluoride on alumina in acetonitrile or 1,2-dimethoxyethane was concluded to be the best reaction system for general use. O-Alkylation of substituted phenols, primary and secondary alcohols, and a glycol was carried out mostly in good yields under mild conditions with simple experimental procedures.
TL;DR: In this article, eleven cupric compounds were screened to determine whether a different cupric anion might give greater and more uniform charring responses with lipid classes on TLC plates than cupric acetate.
Abstract: Eleven cupric compounds were screened to determine whether a different cupric anion might give greater and more uniform charring responses with lipid classes on TLC plates than cupric acetate. A procedure was developed which used 10% CuSO4 in 8% H3PO4 as a charring reagent. Improved reproducibility of charring was obtained by temperature-programmed heating of the thin layer plates from 30 to 180°C at 10 degrees per minute in the oven of a commercial gas-liquid chromatograph.
TL;DR: A colorimetric method for precise and accurate determination of zinc in serum is presented, which does not involve heating, extraction with organic solvents, or a cyanide masking system.
TL;DR: In this article, a quick and very inexpensive method for the analysis of fatty acids derived from soybean lipids is described, which involves extraction of soybeans with petroleum ether, followed by hydrolysis of lipids with KOH/meOH (0.5 M) for 5 min at 100 C followed by esterification with aq. HC1 (36%)/MeOH (4:1, v/v).
Abstract: A quick, reliable and very inexpensive method is described for the analysis of fatty acids derived from soybean lipids. The method involves extraction of soybean lipids with petroleum ether, followed by hydrolysis of lipids with KOH/MeOH (0.5 M) for 5 min at 100 C followed by esterification with aq. HC1 (36%)/MeOH (4:1, v/v) for 15 min at 100 C. No problems were encountered with the esterifica-tion procedure in the presence of water and the procedure gave results comparable to die more conventional BF3/MeOH reagent. The aq. HCI/MeOH reagent is several hundred times cheaper than BF3/MeOH, and does not compromise the efficiency of the reagent.
TL;DR: It is concluded that pAg and pA-silver complexes are useful as general second step reagents for the localization of a variety of antigens in paraffin sections.
Abstract: The protein A-gold (pAg) complex, a useful reagent for electron microscopic localization of antigens in thin sections, is tested for its suitability as second step reagent in light microscopic immu...
Patent•
12 Mar 1982
TL;DR: In this article, a method and device for assaying a test substance utilizing a primary absorbent substance for selectively allowing only a quantity of an analytical reagent proportional to the quantity of test substance to pass therethrough when test substance and reagent are contacted with the primary absorbents is presented.
Abstract: A method and device for assaying a test substance utilizing a primary absorbent substance for selectively allowing only a quantity of an analytical reagent proportional to the quantity of test substance to pass therethrough when test substance and analytical reagent are contacted with the primary absorbent. An analytical absorbent is disposed in a series of zones for sequentially absorbing the analytical reagent which passes through the primary absorbent so that detection of the last zone of absorbed analytical reagent indicates the quantity of test substance. The method comprises passing test substance and analytical reagent through the primary absorbent and then the analytical absorbent followed by detection of the last zone in which analytical reagent is absorbed. The device comprises a funnel with the primary absorbent therein for directing the test substance and analytical reagent to a narrow tube holding the analytical absorbent.
TL;DR: In this paper, a method of synthesizing ketomethylene dipeptides by using homoally-licive Grignard reagents as amino acid analog synthons is described.
TL;DR: Samarium diiodide is an efficient reagent for the reductive cleavage of the ON bond of isoxazoles as mentioned in this paper, and is stable to the reaction conditions, benzylic halides and aldehydes are not.
Patent•
28 Oct 1982
TL;DR: A colorimetric urea determination method, reagent, and reagent kit useful in end point and kinetic Urea determination is disclosed in this paper, where urea in a liquid sample reacts with ophthalaldehyde and a chromogenic compound in the presence of a linear long hydrocarbon chain amidobetaine to produce an intensely colored reaction product.
Abstract: A colorimetric urea determination method, reagent, and reagent kit useful in end point and kinetic urea determination is disclosed Urea in a liquid sample reacts with o-phthalaldehyde and a chromogenic compound in the presence of a linear long hydrocarbon chain amidobetaine to produce an intensely colored reaction product, the concentration of which is linearly related to the urea concentration in the sample
TL;DR: A commercially available enzymatic assay (Boehringer Monotest) was modified to allow a rapid and sensitive determination of cholesterol in membrane lipid extracts by adding 0.5% Triton X-100 to the reagent solution.
TL;DR: Bispyridinesilver permanganate is an easily prepared crystalline relatively stable compounds, soluble in organic solvents; its uses as an oxidizing agent of organic compounds in benzene are described as mentioned in this paper.
TL;DR: In this paper, hydrogen peroxide is determined by a chemiluminescence method with a reagent containing 100 μM luminol and 3 μM microperoxidase at pH 10 (carbonate buffer).