Showing papers on "Reagent published in 1988"
TL;DR: The rate enhancements afforded by chymotrypsin and subtilisin in the transesterification reaction in octane are of the order of 100 billion-fold; covalent modification of the active center of the enzymes by a site-specific reagent renders them catalytically inactive in organic solvents.
948 citations
TL;DR: In this paper, the concentration of hydrogen peroxide (H2O2) in distilled water, drinking water and in different types of surface and rain waters can be easily determined by a photometric method in which N,N-diethyl-p-phenylenediamine (DPD) is oxidized by a peroxidase catalyzed reaction.
819 citations
TL;DR: In this article, three methods have been used to extract iron (Fe) and aluminium (Al) from a wide range of soils using Moessbauer spectroscopy, including pyrophosphate, acid-oxalate, and dithionite-citrate reagents.
Abstract: Three methods have been used to extract iron (Fe) and aluminium (Al) from a wide range of soils. The three extractants were pyrophosphate reagent (p), acid-oxalate reagent (o), and dithionite-citrate reagent (d), and each reagent is thought to extract different forms of Fe and Al. The forms of Fe in the soils were studied before and after extraction using Moessbauer spectroscopy. Pyrophosphate-extractable Fe (Fep) does not specifically relate to any particular form of Fe in soils and it should not be used to estimate Fe in humus complexes. In some soils (e.g., Spodosol, Ochrept) Fep arises from Fe in ferrihydrite. In other soils (Ultisol, Hydrandept) Fep arises from goethite and ferrihydrite which is dispersed by pyrophosphate. Alp corresponds to Al in humus complexes and, in most soils, can be used to estimate Al in such complexes. Al and Si in allophane and imogolite were extracted in acid-oxalate reagent, and could be estimated from Alo-Alp and Sio, provided large amounts of ferrihydrite were not present. Ferrihydrite was also extracted in acid-oxalate reagent and, assuming complete extraction, could be estimated by multiplying Feo by the factor 1.7. Dithionite-citrate reagent dissolved goethite and hematite in addition to ferrihydrite. In some soils repeated extractions were required to dissoive most of the goethite and hematite. Quantitative estimates of Fe in goethite and hematite can be made from Fed -Feo. Other techniques, however, such as X-ray diffraction and Moessbauer spectroscopy, were necessary to identify iron oxides positively in most soils.
505 citations
TL;DR: The bicinchoninic acid (BCA) copper reagent, developed for quantification of proteins, was found to react with thiol reagents in a linear and reproducible manner.
301 citations
TL;DR: The common phospholipids from biological sources were quantitated using phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy in conjunction with an analytical reagent composed of two parts: 1) 2 ml of reagent chloroform in which was dissolved 0.01-100 mg of crude tissue lipid extracted from tissue sources using chloro Form 2:1, the extract having been washed with 0.2 vol.
231 citations
230 citations
Patent•
24 Aug 1988
TL;DR: In this article, improved specific binding assay devices comprising a chromatographic medium including a reaction site at which a specific binding reagent is immobilized, a sample application well located adjacent to the chromatogram and offset upstream from the reaction site, and a liquid absorption blotter offset downstream from the reactivity site are described.
Abstract: The present invention relates to improved specific binding assay devices comprising a chromatographic medium including a reaction site at which a specific binding reagent is immobilized, a sample application well located adjacent to the chromatographic medium and offset upstream from the reaction site, and a liquid absorption blotter offset downstream from the reaction site.
191 citations
TL;DR: In this article, the partial oxidation of methane to formaldehyde by molecular oxygen has been studied, with molybdenum(VI) oxide-silica and related catalysts.
172 citations
TL;DR: It has been found that partially protected inositols are phosphorylated in near quantitative yields by use of N, N -diisopropyl dibenzyl phosphoramidite, 1- H -tetrazole and MCPBA in CH 2 Cl 2.
170 citations
TL;DR: In this article, the dimerization of (p-hydroxyphenyl)acetic acid by hydrogen peroxide in the presence of peroxidase has been adapted to the determination of HPO in seawater.
Abstract: The dimerization of (p-hydroxyphenyl)acetic acid by hydrogen peroxide in the presence of peroxidase has been adapted to the determination of hydrogen peroxide in seawater. The fluorometric method presented requires only one mixed reagent for sample analysis and produces a stable product that does not require immediate measurement. Changes in reaction stoichiometry resulting from naturally occurring organic material have been addressed. The detection limit, defined as 3 times the standard deviation of the blank, is 4 and 4 nM for open ocean and coastal seawater, respectively.
168 citations
TL;DR: The reaction between (C5Me5)SiMe3 and group 4 element tetrahalides MX4 (M Ti, Cl, Br, I, Zr, Hf, X ǫ, Cl) gives the corresponding (η5-C5me5)MX3 derivatives in nearly quantitative yields in one-step procedure without the need for further purification as discussed by the authors.
TL;DR: T-butyl 2,2,2-trichloroacetimidate is an efficient reagent for the preparation of t- butyl ethers and esters in the presence of a catalytic amount of boron trifluoride etherate.
TL;DR: In this article, the reagent in methanol with monohydric phenols directly yields p -quinone ketals, also in good yields, and 4-alkyl-4-methoxycycloxycyclohexadienones.
Patent•
17 Nov 1988TL;DR: In this article, a rotatable reaction table is arranged in a side-by-side relation to the sample table and the reagent table, and a single pipetting device is operated in such a manner as to transfer all the samples to the reaction vessels followed by the supply of the reagents to these reaction vessels.
Abstract: An automatic analyzing system has a sample table for supporting a plurality of sample vessels and a reagent table for supporting a plurality of reagent vessels. The sample table and the reagent table are fixed to a common drive shaft. The system further has a rotatable reaction table for supporting a plurality of reaction vessels. The reaction table is arranged in a side-by-side relation to the sample table and the reagent table. The system further has a single pipetting device disposed between the reaction table and the stack of the sample table and the reagent table for a swinging motion therebetween so as to suck samples and reagents from the sample vessels and the reagent vessels and to deliver the same to the reaction vessels. The pipetting device is operated in such a manner as to transfer all the samples to the reaction vessels followed by the supply of the reagents to these reaction vessels.
TL;DR: The method has been applied successfully to the determination of hydrazine in polluted river water and in a biological fluid and the optimum reaction conditions, such as time, temperature, pH, reagent concentration and effect of interferents, were determined for full colour development.
Abstract: A sensitive spectrophotometric method is proposed for the determination of trace amounts of hydrazine by a one-step condensation reaction with vanillin. The dye thus formed gives a yellow colour in acidic medium, has a maximum absorbance at 400 nm and obeys Beer's law in the range 0.65–5 µg of hydrazine in 10 ml of the final solution. The optimum reaction conditions, such as time, temperature, pH, reagent concentration and effect of interferents, were determined for full colour development. The method has been applied successfully to the determination of hydrazine in polluted river water and in a biological fluid.
TL;DR: In this article, the reaction of OH radicals with dimethyl sulfoxide (DMSO) in aqueous solutions was investigated and the maximum yield in the radiolysis experiments was 86%.
Abstract: The reaction of OH radicals with dimethyl sulfoxide (DMSO) in aqueous solutions was investigated. The OH radicals were produced via radiolysis of N/sub 2/O saturated aqueous solutions and via Fenton's reagent. With Fenton's reagent the authors observed a quantitative conversion of OH radicals to CH/sub 3/ radicals, giving CH/sub 4/ and C/sub 2/H/sub 6/. The maximum yield in the radiolysis experiments was 86%. In both cases C/sub 2/H/sub 6/ was a major product with the C/sub 2/H/sub 6//CH/sub 4/ ratio as high as 45. The C/sub 2/H/sub 6//CH/sub 4/ ratio depends on the steady-state concentration of CH/sub 3/ radicals and on the DMSO concentration. Results show that CH/sub 3/ radicals in addition to abstracting hydrogen from methanesulfinic acid also abstract hydrogen from DMSO to give CH/sub 4/. In the radiolysis of deuteriated DMSO they observed a much higher ethane/methane ratio than in the nondeuteriated DMSO. The isotope effect supports the hydrogen abstraction from DMSO by CH/sub 3/ radicals. 9 references, 6 tables.
Patent•
25 May 1988TL;DR: In this paper, a II-VI compound, such as zinc sulfide, is deposited from a gaseous mixture in a reactor which is compatible with a vacuum processing system which includes vacuum wafer transport.
Abstract: A II-VI compound, such as zinc sulfide, is deposited from a gaseous mixture in a reactor which is compatible with a vacuum processing system which includes vacuum wafer transport. Two manifolds are used, each connected to a supply of one or more reagent gases, to improve uniformity.
TL;DR: In this paper, the asymmetric ene reaction of prochiral aldehydes with alkenes has been effected by chiral organoaluminum reagent providing optically active homoallylic alcohols in both enantiomeric forms with high enantiomic purity.
TL;DR: The direct sequencing of DNA generated by the polynucleotide chain reaction, via the incorporation of phosphorothioate nucleotides and followed by treatment with an alkylating reagent that cleaves specifically at the phosphorOTHioate positions, is described.
Abstract: The direct sequencing of DNA generated by the polynucleotide chain reaction, via the incorporation of phosphorothioate nucleotides and followed by treatment with an alkylating reagent that cleaves specifically at the phosphorothioate positions, is described. The Taq polymerase used in the amplification reaction incorporates the Sp-diastereomer of the deoxynucleoside 5'-O-(1-thiotriphosphates) as efficiently as the natural nucleotides. Chemical degradation of the phosphorothioate-containing DNA fragment can be performed with either 2-iodoethanol or 2,3-epoxy-1-propanol. The higher reactivity of 2,3-epoxy-1-propanol allows less reagent to be used to obtain the same amount of degradation as with 2-iodoethanol.
TL;DR: Classon et al. as mentioned in this paper proposed a halogenation reagent system for the mild one-step conversion of alcohols into iodides or bromides, which was shown to be useful for the conversion of bromide and iodide.
Abstract: The Journal of Organic Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 New halogenation reagent systems useful for the mild one-step conversion of alcohols into iodides or bromides Bjoern Classon, Zhengchun Liu, and Bertil Samuelsson J. Org. Chem., 1988, 53 (26), 6126-6130• DOI: 10.1021/jo00261a032 • Publication Date (Web): 01 May 2002 Downloaded from http://pubs.acs.org on March 9, 2009
TL;DR: In this paper, the reaction of prenylzinc reagent wlih α-imino 8-(-)phenylmenthyl ester (10) with heteroatom substituted allylic organometalic compounds (15) gave the corresponding α-heterostom substituted amino acid derivatives.
TL;DR: 1-Pyrenyldiazomethane (PDAM), a new fluorescent labeling reagent, was developed for liquid chromatographic determination of carboxylic acid and was more stable than the other previous diazoalkane type reagents.
Abstract: 1-Pyrenyldiazomethane (PDAM), a new fluorescent labeling reagent, was developed for liquid chromatographic determination of carboxylic acid. PDAM was more stable than the other previous diazoalkane type reagents. The reagent readily reacted with carboxylic acids to give stable and strongly fluorescent 1-pyrenylmethyl ester derivatives without a catalyst and heating. PDAM derivatives of short- and long-chain fatty acids and prostaglandins were satisfactorily separated on a reversed-phase column and were sensitively detected fluorometrically at 395 nm with excitation at 340 nm. Detection limits of PDAM derivatives of both fatty acids and prostaglandins were 20-30 fmol.
TL;DR: A convenient, inexpensive method for the preparation of [(Ph 3 P)CuH] 6, a versatile reagent for the conjugate reduction of α,β-unsaturated carbonyl compounds, has been developed.
TL;DR: Palladium zero converts triphenylbismuth quantitatively to diphenyl and metallic bismuth in excellent yield as discussed by the authors, and many other derivatives of Bi (III) and Bi(V) are similarly transformed to diaryls.
Patent•
02 Mar 1988
TL;DR: In this paper, an element for analysis of a liquid sample including a capillary containing a fixed reagent in fluid communication with reagent reservoirs and a waste liquid reservoir is presented.
Abstract: An element for analysis of a liquid sample including a capillary containing a fixed reagent in fluid communication with reagent reservoirs and a waste liquid reservoir. A sample introducing means is provided which permits analyte in a sample to interact with the fixed reagent. A labelled reagent is provided which interacts with either the fixed reagent or the analyte in a manner which permits detection of the concentration of analyte in the sample. The capillary, reagent reservoirs, waste liquid reservoir and the sample introducing means are arranged within a common housing so that reagent waste liquid need not be removed from the element.
TL;DR: In this paper, the critical role of metals in a-face selective alkene functionalizations is exemplified by Diels-Alder reactions, osmylations, hydrogenations, conjugate additions (hydride, organocopper reagents, alkylmagnesium halides) of N-enoyl-bornane-10,2-sultams as well as by protonations and aldolizations of "enolates" derived from the same auxiliary.
Abstract: The critical role of metals in a-face selective alkene functionalizations is exemplified by Diels-Alder reactions, osmylations, hydrogenations, conjugate additions (hydride, organocopper reagents, alkylmagnesium halides) of N-enoyl-bornane-10,2-sultams as well as by protonations, alkylations and aldolizations of "enolates" derived from the same auxiliary. In extension of the magnesium-ene process catalytic intramolecular palladium-ene reactions are presented. Thus, Pd(dba) /PPh3- or Pd(PPh)3-catalyzed stereoselective cyclizations of acetoxy-2,7(8?- dienes gave 1-vinyl-2-methylene- or 1,2-divinyl-substituted cyclopentanes (or cyclohexanes) consistent with a cis-insertion/p-elimination process.
Patent•
11 Mar 1988
TL;DR: In this article, a method and reagent system are disclosed for the rapid isolation, identification and/or analysis of leukocytes from a whole blood sample. But this method is not suitable for the analysis of the leukocyte fraction of whole blood.
Abstract: A method and reagent system are disclosed for the rapid isolation, identification and/or analysis of leukocytes from a whole blood sample. The method and reagent system of this invention has application to any environment in which the study and/or analysis of the leukocyte fraction of whole blood requires their isolation in their native or near native state. One of the environments in which this invention can be used to advantage is in the performance of white cell differentiation on automated instrumentation designed for that purpose. In one of the preferred embodiments of this invention, the lytic reagent can contain a mixture of both formic and acetic acid, with the formic acid comprising the major component thereof and the acetic acid being present in only minor quantities, (if at all). This reagent system is used to selectively effect stromatolysis of red blood cells and create subtle modifications to the leukocyte population to enable their automated differentiation into five (5) sub-populations. The advantage and uniqueness of this reagent system is the surprising speed at which it is able to effect the foregoing objectives (generally less than 10 seconds at room temperature) and the ability to further differentiate the leukocyte population (notably, the granulocyte population). Following stromatolysis, a quenching agent is added to retard the reactivity of the lytic reagent system and, thus, inhibit any further dramatic changes to the leukocyte population. The treatment of the whole blood sample in the foregoing manner is further unique in that the leukocyte fraction of the sample has retained its characteristic immunochemical response.