Showing papers on "Reagent published in 1995"

2 Chloro 4,4,5,5 tetramethyl 1,3,2 dioxaphospholane, a reagent for the accurate determination of the uncondensed and condensed phenolic moieties in lignins

Abstract: The use of 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane as a phosphitylation reagent in quantitative 31P NMR analysis of the hydroxyl groups in lignins has been thoroughly examined, and an experimental protocol recommended for spectra acquisition has been developed. Quantitative analysis of six “standard lignins” gave results comparable to those obtained by other methods of analysis. Excellent resolution of the various phenolic hydroxyl environments including those present in condensed moieties was observed. However, this was at the expense of resolution in the aliphatic hydroxyl region, where no distinction between primary, secondary, and the erythro and threo forms of the secondary hydroxyls of the ,l?-0-4 bonds can be made.

Short technical reports. Modification of the TRI reagent procedure for isolation of RNA from polysaccharide- and proteoglycan-rich sources.

Abstract: A modification of the TRI Reagent procedure has been elaborated for isolation of RNA from polysaccharide- and proteoglycan-rich material. In the modified procedure, RNA is precipitated from the aqueous phase by the combined action of isopropanol and a high-salt concentration. Under these conditions, RNA is effectively precipitated while contaminating polysaccharides and proteoglycans remain in the soluble form. The modified precipitation does not prolong or increase the complexity of the TRI Reagent procedure. The new procedure was tested by isolation of RNA from polysaccharide- and proteoglycan-rich tissues such as rat liver and aorta.

Glucose Oxidase as an Analytical Reagent

Abstract: Glucose oxidase (EC 1.1.3.4) is the most widly employed enzyme as analytical reagent. This is the result of (1) its utility in the determination of glucose, an analyte of wide analytical interest, and (2) its relatively low cost and good stability that make the glucose/glucose oxidase system a very convenient model for method development (particularly in the area of biosensors). This review discusses in detail enzyme structure, biocatalysis, enzymes as analytical reagents, properties of glucose oxidase (including a historical account), and the use of glucose oxidase as an analytical reagent in homogeneous systems as well as an immobilized reagent.

Diagnostic flow cell device

Abstract: The present invention provides a diagnostic flow cell for determining the presence or amount of an analyte which may be contained in a test sample. The flow cell comprises a spacing layer having a longitudinal void disposed between a pair of opposed substrates. The spacing layer and the opposed substrates define a flow channel wherein reagent means can be immobilized. When the immobilized reagent means is contacted with an analyte, the reagent means can produce an electrically, optically, or electrically and optically detectable response to the analyte. Hence, the reagent means that is immobilized within the flow channel can comprise (i) a counter electrode, a reference electrode and a working electrode, (ii) an optically sensitive dye or (iii) a counter electrode, a reference electrode and a working electrode and an optically sensitive dye. The flow cell can be interfaced with means for introducing a test sample into and out of the flow cell's flow channel and detection means for detecting a signal generated by the immobilized reagent means. The present invention also provides methods for detecting the presence or amount of an analyte which may be contained in a test sample.

Automated slide processing apparatus with fluid injector

Abstract: An automated immunostaining apparatus having a reagent application zone and a reagent supply zone. The apparatus has a carousel slide support supporting a plurality of slide supports thereon, and drive device engaging the carousel slide support for consecutively positioning each of a plurality of slide supports in the reagent application zone. The apparatus also has a carousel reagent support having a plurality of reagent container supports thereon, and drive device engaging the carousel for rotating the carousel and positioning a preselected reagent container support in the reagent supply zone. The apparatus also has a reagent delivery actuator device positioned for engaging a reagent container positioned on a container support in the reagent delivery zone and initating reagent delivery from the reagent container to a slide supported on a slide support in the reagent receiving zone.

Source reagent liquid delivery apparatus, and chemical vapor deposition system comprising same

Abstract: A process and apparatus for delivering an involatile reagent in gaseous form, wherein an involatile reagent source liquid is flash-vaporized on a vaporization matrix structure (26) at elevated temperature. A carrier gas may be flowed past the flash vaporization matrix structure to yield a carrier gas mixture containing the flash vaporized source reagent. The vaporization matrix structure (26) preferably has a high surface-to-volume ratio, and may suitably comprise a foraminous matrix element such as screen mesh onto which the reagent source liquid is distributed for flash vaporization. The invention is particularly useful for delivery of Group II reagents and compounds and complexes of early transition metals such as zirconium and hafnium, and may be usefully employed with Group II beta-diketonate source layers, e.g., of YBaCuO, BiSrCaCuO, and TlBaCaCuO types, as well as for forming interlayers of Group II metal fluorides between superconductor or gallium arsenide overlayers, and for depositing thin films of photonic and ferroelectric materials, e.g., BaTiO3, BaxSr1-xNb2O6, and PbZr1-xTixO3.

Evaluation of use of tris(2,2'-bipyridyl)ruthenium(III) as a chemiluminescent reagent for quantitation in flowing streams

Abstract: Three approaches are comparatively evaluated for the use of tris(2,2'-bipyridil)ruthenium(II), Ru(bpy) 3 3+ , as a chemiluminescent reagent in flow streams: (1) external generation of the reactive Ru(bpy) 3 3+ oxidation state followed by contact with the analyte, (2) in situ generation of the Ru(bpy) 3 3+ species from a solution mixture of the analyte and the Ru(bpy) 3 2+ species as it passes through the reaction/observation cell, and (3) in situ generation of the Ru(bpy) 3 3+ species from the Ru(bpy) 3 2+ species immobilized within the observation cell. Oxalate and proline were used as representative analytes for comparison of these three modes with respect to the influence of experimental variables (reagent concentration, flow rate, pH) and resulting analytical performance (detection limit, working range, measurement precision). Additionally, a comparison was made of the relative ECL intensities obtained for a variety of analytes including oxidate, amino acids, aliphatic amines, peptides, and NADH. We find that each approach has its unique set of strengths and weaknesses. The external generation mode yields the most intense emission, especially for simple aliphatic amines, but working curves have poor linearity, and emission intensities have a large dependence on solution flow rate. The in situ immobilized approach results in lower intensities but yields the widest linear dynamic ranges, is most conservative of reagent, and has a particular sensitivity advantage for proline and NADH determinations. The in situ solution mode is superior for the detection of amino acids such as hyptophan, 5-hydroxyhyptophan, and histidine and has time, convenience, and reliability advantages

Precursor compositions for chemical vapor deposition, and ligand exchange resistant metal-organic precursor solutions comprising same

Abstract: A metal source reagent liquid solution, comprising: (i) at least one metal coordination complex including a metal to which is coordinatively bound at least one ligand in a stable complex, wherein the ligand is selected from the group consisting of: β-diketonates, β-ketoiminates, β-diiminates, C1 -C8 alkyl, C2 -C10 alkenyl, C2 -C15 cycloalkenyl, C6 -C10 aryl, C1 -C8 alkoxy, and fluorinated derivatives thereof; and (ii) a solvent for the metal coordination complex. The solutions are usefully employed for chemical vapor deposition of metals from the metal coordination complexes, such as Mg, Ca, Sr, Ba, Sc, Y, La, Ce, Ti, Zr, Hf, Pr, V, Nb, Ta, Nd, Cr, W, Pm, Mn, Re, Sm, Fe, Ru, Eu, Co, Rh, Ir, Gd, Ni, Tb, Cu, Dy, Ho, Al, Tl, Er, Sn, Pb, Tm, Bi, and/or Yb. The solvent may comprise glyme solvents, alkanols, organic ethers, aliphatic hydrocarbons, and/or aromatic hydrocarbons. Solutions of the invention having two or more metal coordination complexes are resistant to detrimental ligand exchange reactions which adversely affect the stability and/or volatilizability of the metal complex for CVD applications.

Methods and device for detecting and quantifying substances in body fluids

Abstract: An in vivo method and apparatus for detecting an analyte in an individual. A sensor that includes a fluorescence reagent is placed in communication with the body fluids of the individual suspected of containing the analyte in such a way that once in place said sensor does not exit the skin of the individual. The sensor is configured to retain the fluorescence reagent while allowing analyte to diffuse into and out of said sensor. The sensor is illuminated transdermally, and the fluorescence from the fluorescence reagent associated with the presence of the analyte is measured.

Osmium-containing redox mediator

Abstract: A new group of Os(II) and Os(III) compounds useful as redox mediators in electrochemical biosensors is presented. These compounds have 1) low oxidation potential, 2) fast reaction kinetics between the electroactive center of an enzyme and the compound, 3) slow oxidation of osmium by oxygen, and 4) excellent solubility in aqueous medium. The figure shows is a cyclic voltammagram of the compound [Os(III)(bpy)2imCl]Cl2, wherein im is imidazolyl. These mediator compounds are particularly useful as a component of a reagent for measuring analytes from a biological fluid, such as blood.

Determination of biothiols by bromobimane labeling and high-performance liquid chromatography.

Abstract: Publisher Summary This chapter discusses the determination of biothiols by bromobimane labeling and high-performance liquid chromatography (HPLC). Most thiols undergo rapid autoxidation when exposed to air at neutral or basic pH, a process that is catalyzed by heavy metals of the type found in most cells. A primary consideration in preparing and analyzing samples for thiols is to prevent their oxidative loss during the sample preparation and analysis. This can be accomplished by alkylation of the thiol group near neutral pH with the bromobimanes. The chapter focuses on monobromobimane (mBBr), an uncharged reagent that readily penetrates cells, 1-4 and 4- p -sulfobenzoyloxymethyl-6-bromomethy-1-3,7-dimethyl-1,5-diazabicyclo [3.3.0] octa-3,6-diene-2,8-dione (SBBr), an anionic reagent that does not enter cells. Many biological thiols are relatively small and ionic, which makes them easy to separate from more hydrophobic thiols but difficult to separate from each other using reversed-phase HPLC. The bimane derivatives of these ionic thiols are more hydrophobic than the thiol itself and are readily resolved by HPLC analysis on silica-based reversed-phase columns. The highly selective, rapid reactivity of bromobimanes toward thiols, the stability and fluorescence yield of the thiol derivatives, the ease of separation of the derivatives by reversed-phase HPLC, and the availability of both cell-penetrating and nonpenetrating forms make the use bromobimanes an extremely powerful approach to the analysis of low-molecular-weight biothiols.

Supercritical fluid extraction of uranium and thorium from nitric acid solutions with organophosphorus reagents.

Abstract: Extraction techniques for the recovery of uranium and transuranic elements from acid waste solutions are important in nuclear waste management. This paper examines the feasibility of extracting uranyl and thorium ions from nitric acid solutions with supercritical CO{sub 2} containing the different organophosphorus reagents. In this study, an organophosphorus reagent is dissolved in supercritical CO{sub 2} by passing the fluid through a reagent vessel placed upstream of the sample vessel in the extractor. Using TBPO or TOPO in supercritical CO{sub 2}, effective extraction of uranyl and thorium ions can be achieved even in dilute HNO{sub 3} solutions, thus yielding the possibility of reducing acidic waste volumes in nuclear waste treatment. The results may form the basis of a novel extraction process for the treatment of acidified nuclear wastes, while minimizing the production of secondary wastes. 12 refs., 2 figs., 2 tabs.

Blood glucose strip having reduced side reactions

Abstract: A reagent strip for measuring glucose concentration in a biological fluid containing red blood cells has reduced interference of hematocrit with the glucose measurement. When a biological fluid contacts the strip, it causes, in a reagent impregnated in the strip, a color change which is a measure of the glucose concentration in the fluid. However, the color change is also affected by the red blood cell concentration (hematocrit), thereby reducing the accuracy of the glucose measurement. The hematocrit effect is reduced by adding to the reagent a component, such as imidazole or imidazole and N-acetylglucosamine, for minimizing side reactions of the glucose, or its reaction products, with the fluid.

Combustion chemical vapor deposition of films and coatings

Abstract: A method for applying coatings to substrates using combustion chemical vapor deposition by mixing together a reagent and a carrier solution to form a reagent mixture, igniting the reagent mixture to create a flame, or flowing the reagent mixture through a plasma torch, in which the reagent is at least partially vaporized into a vapor phase, and contacting the vapor phase of the reagent to a substrate resulting in the deposition, at least in part from the vapor phase, of a coating of the reagent which can be controlled so as to have a preferred orientation on the substrate, and an apparatus to accomplish this method.

Automated analyzer with reagent agitating device

Abstract: An analyzer for performing automated assay testing. The analyzer includes a storage and conveyor system for conveying cuvettes to an incubation or processing conveyor, a storage and selection system for test sample containers, a storage and selection system for reagent containers, sample and reagent aspirating and dispensing probes, a separation system for separating bound from unbound tracer or labeled reagent, a detection system and date collection/processing system. All of the subunits of the machine are controlled by a central processing unit to coordinate the activity of all of the subunits of the analyzer. The analyzer is specifically suited for performing heterogeneous binding assay protocols, particularly immunoassays.

Voltage sensing by fluorescence resonance energy transfer

Abstract: Compositions and methods for use in generating fast ratiometric voltage-sensitive fluorescence changes in single or multiple cells systems. A first reagent is a membrane-bound hydrophobic fluorescent anion which rapidly redistributes from one face of the plasma membrane to the other in response to the transmembrane potential, as described by the Nernst equation. A voltage-sensitive fluorescent readout is created by labeling the intracellular or extracellular surface of the cell with a second reagent comprising a fluorophore which can undergo energy transfer with the first reagent or a quencher for the first reagent. Quenching or FRET between the two reagents is disrupted when the membrane potential is depolarized, because the anionic first reagent is pulled to the intracellular surface of the plasma membrane far from the asymmetrically bound second reagent. In preferred embodiments of the invention, the first and second reagents are bound together by a suitable linker group.