title stringlengths 0 1.13k | abstract stringlengths 1 15.7k | PMID int64 22 36.5M |
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Identification of an organic compound leached from a membrane filter. | An organic compound leached from a Millipore HA filter has been identified as the non-ionic surfactant polyoxyethylene nonylphenyl ether with a degree of polymerization of 4-10 for the ethylene oxide unit. It is suggested that the Millipore HA filter should be used only after several rinses with sample or doubly-distil... | 18,962,149 |
Contributions to the basic problems of complexometry-XXVII. Influence of magnesium on masking of calcium with fluoride in the determination of manganese. | Determination of manganese in the presence of calcium and magnesium after their masking with ammonium fluoride was reinvestigated. Normally such a determination gives low results caused by co-precipitation of manganese with calcium fluoride. It has been found that the co-precipitation is highest when magnesium is absen... | 18,962,164 |
Determination of acid-soluble and total rhodium on alumina-supported catalysts. | Characterization of alumina-supported catalysts required determination of rhodium by atomic-absorption spectroscopy (AAS). Catalysts were loaded with 0.1-2.0% rhodium chloride and calcined at 400 degrees . Rhodium remaining as the chloride was regarded as the soluble form, while that converted into the oxide or bonded ... | 18,962,171 |
Extraction and spectrophotometric determination of thallium(III) with thiothenoyltrifluoroacetone. | A procedure is described for the extractive photometric determination of thallium(III) with thiothenoyltrifluoroacetone in carbon tetrachloride. Thallium(III) is extracted quantitatively at pH 4-5 and the bright yellow extract obeys Beer's law over the Tl(III) concentration range 2.5-17.5 mug/ml, at 440 nm. Thallium(II... | 18,962,181 |
Sensitivity enhancement in flameless atomization systems by use of a rigid tungsten collar. | Sensitivity enhancement was achieved in a flameless atomization system by the insertion of a rigid tungsten "collar" 1 cm long and 0.5 mm thick. With such a collar the electrical and thermal properties of the furnace were essentially those of the original tube, and the existing power pack could be used without modifica... | 18,962,192 |
Quantitative treatment of substituent effects in the polarographic investigations of some potential antineoplastic 2-amino-4-aryl-5-phenylazothiazoles. | Polarographic reduction of 2-amino-4-aryl-5-phenylazothiazoles takes place in a single 2-electron transfer, giving a diffusion-controlled irreversible wave in the pH range 2.0-10.0. Substituents in the 4-position of the thiazole moiety shift the half-wave potential through conjugation of the system. A correlation of E(... | 18,962,218 |
Assessment of a new method for the differential pulse polarographic determination of silicon in steel. | A procedure is described by which silicon in steel may be determined by differential pulse polarography after removal of iron. Silicomolybdic acid is formed within 20 min by reaction of the silicon with molybdate in the presence of methyl ethyl ketone: subsequent addition of citrate buffer prevents interference from ph... | 18,962,245 |
[Not Available]. | Acids conjugated to various phenothiazine derivatives are titrated directly with sodium hydroxide, by means of an automatic thermometric titrimeter. The titration curves have sharp breaks, suitable for analytical use, and these are discussed, in the case of promethazine hydrochloride, as functions of various parameters... | 18,962,270 |
4-Amino-3-methyl-5-mercapto-1,2,4-triazole as a gravimetric reagent for determination of silver in silver compounds, alloys and complexes. | A simple, convenient and accurate gravimetric method for the determination of silver is presented. 4-Amino-3-methyl-5-mercapto-1,2,4-triazole precipitates silver quantitatively from ammoniacal tartrate medium. The complex is weighed as AgC(3)H(5)N(4)S after drying at 120-30 degrees . Separation of silver from a large n... | 18,962,291 |
Potentiometric determination of the dissociation constants of an asymmetric sorbent containing l-proline, and the stability constants of its Cu(II) complexes. | The dissociation constants of the carboxyl groups (pK(a1) = 2.2, n = 1.8) and amino groups (pK(a2) = 9.5, n(2) = 1.6) of a sorbent prepared by reacting l-proline with a cross-linked chloromethylated styrene polymer have been determined by potentiometric titration. The potentiometrically measured stability constants of ... | 18,962,307 |
Furoin thiosemicarbazone as an analytical reagent for nickel(II), palladium(II) and copper(II). | Furoin thiosemicarbazone (FTS) reacts with Ni(II), Pd(II) and Cu(II) in aqueous medium, giving yellow solutions at pH 9, 6 and 3 respectively. The complexes have absorption maxima at 360 nm for Ni(II) and Pd(II) and 355 nm for Cu(II). At these wavelengths the reagent absorbance is negligible. The molar absorptivities a... | 18,962,319 |
Gas chromatographic study of volatile oxides and hydroxides of Tc, Re, Ru, Os and Ir-I Investigation by isothermal gas chromatography. | Traces of radioactive elements were produced by the irradiation of uranium foils (93% (235)U) with thermal neutrons, and of gold foils with 600-MeV protons. They were volatilized as oxides and hydroxides by heating at 1500 degrees in an O(2) or O(2)/H(2)O stream and separated by adsorption chromatography on quartz gran... | 18,962,322 |
Analytical applications of a liquid anion-exchanger for the separation of uranium(IV) in malonate solution. | Uranium was quantitatively extracted with 4% Amberlite LA-1 in xylene at pH 2.5-4.0 from 0.001 M malonic acid. It was stripped from the organic phase with 0.01 M sodium hydroxide and determined spectrophotometrically at 530 nm as its complex with 4-(2-pyridylazo) resorcinol. Of various liquid anion-exchangers tested, A... | 18,962,334 |
[Not Available]. | The determinations are based on potentiometric titration data (volume of reagent, potential). To avoid any systematic error, the acidity constants are refined together with every other significant parameter (initial protolyte concentration, concentration of impurities, electrode chain characteristics ...) with the prog... | 18,962,339 |
Spectrophotometric determination of bismuth with diethylenetriaminepenta-acetic acid. | Diethylenetriaminepenta-acetic acid is used for spectrophotometric determination of bismuth (at 270 nm) in 1.6 M perchloric acid. The system obeys Beer's law in the range 1-40 mug/ml. The method has been tested for the determination of bismuth in pure lead and polymetallic ores. | 18,962,348 |
Benzohydroxamic acid as a reductometric titrant determination of manganese in ores and alloys. | Benzohydroxamic acid has been employed as a reductometric titrant for the determination of manganese in various ores and alloys. The determination is based on the fact that benzohydroxamic acid reduces Mn(VII) quantitatively to Mn(II) in 1.5N sulphuric acid. | 18,962,356 |
Spectrophotometric determination of micro amounts of hydrazine and hydroxylamine alone and in the presence of each other. | Hydrazine and hydroxylamine alone or in the presence of each other are determined at concentrations of 1-10 microg/25 ml with a relative precision of 3-0.8% by using iron(III) in the presence of Ferrozine. | 18,962,372 |
[Remarques sur le microdosage du bore et du germanium dans les composes organiques et mineraux]. | A wet destruction in a Kjeldahl flask followed by spectrophotometric measurement with azomethine H as reagent, combustion in oxygen in a Parr bomb, and destruction by heating with sodium peroxide followed by acidimetric titration of the mannitol-boric acid complex have been tested for the microdetermination of boron in... | 18,962,382 |
Automated continuous-flow determinations of serum proteins by pulse polarography. | A new flow-through cell is described for application of the dropping mercury electrode to the determination of serum proteins in an automated continuous-flow system. By using differential pulse polarography with short controlled drop times, it is possible to run a rapid automated system at sampling rates of up to 120 p... | 18,962,388 |
Influence of the solvent medium on formation of Cu(II), Zn(II) and Ni(II) hexacyanocobaltates. | Investigations on precipitation of metal hexacyanocobaltates from mixed solvent media have confirmed the earlier interpretation of the mechanism and provided further insight into it. | 18,962,402 |
Autoprotolysis constants and acid-base properties of propylene glycol mixtures. | The autoprotolysis constants of propylene glycol and its mixtures with water, acetone, propan-2-ol and chloroform have been determined potentiometrically. In the same solvent mixtures the protolysis constants of the phthalic acid-hydrogen phthalate system have been evaluated and indicate that the solvent is more acidic... | 18,962,406 |
Electrothermal atomic-absorption spectrometry of antimony by use of a molybdenum micro-tube atomizer. | Electrothermal atomization of antimony has been investigated to clarify the atomization characteristics and interferences from diverse elements, for accurate determination of traces of antimony. Thiourea served to lower the atomization temperature of antimony and to improve the sensitivity. Germanium and phosphoric aci... | 18,962,417 |
Anion-exchange behaviour and separation of metal ions on deae-cellulose in oxalic acid media. | The anion-exchange behaviour of 30 metal ions on a weakly basic ion-exchanger (DEAE-cellulose) has been investigated in aqueous oxalic acid media over the concentration range 0.0010-0.50 M. There are marked differences in adsorbability between ter- and quadrivalent metal and bivalent metal groups; the system offers goo... | 18,962,418 |
Spot-test detection of aryl hydrazines, hydrazones, osazones, oximes and aromatic amines. | Arylhydrazines are detected by oxidation with N-bromosuccinimide and coupling with resorcinol to form azo-dyes which are intensely coloured in alkaline media. Hydrazones and osazones are hydrolysed to form the arylhydrazines, which are then tested for 4-Nitro- and 2,4-dinitrophenylhydrazines are tested for by forming t... | 18,962,427 |
Comparison of experimental and calculated relative sensitivity coefficients for spark-source mass-spectrometry of metals. | Sensitivity calibration has been performed for the spark-source mass-spectrometric analysis of iron, copper and aluminium matrices, with standard reference materials. The experimental relative sensitivity coefficients, corrected for discrimination effects in the mass spectrometer, are compared with values obtained with... | 18,962,433 |
Unusual complexing properties of 2-(2'-pyridyl)- and 2-hydrazino-8-hydroxyquinoline. | The ligands 2-(2'-pyridyl)- and 2-hydrazino-8-hydroxyquinoline form terdentate complexes with a 5,5-bicyclic ring system, the stabilities being greater than those of the corresponding 8-hydroxyquinolinates. This study affords a more complete picture of the behaviour of terdentate 2-substituted 8-hydroxyquinolines. Solu... | 18,962,435 |
New chromogens of the ferroin type-IX 2-pyridyl and pyrazinylhydrazones of some pyridyl, pyrazinyl and pyridazinyl ketones and of isatin and phenylglyoxal. | Chromogenic properties of 22 new hydrazones, all ferroin-type compounds, have been evaluated with respect to iron(II), copper(I), cobalt(II) and nickel(II). Some show promise as sensitive reagents for the determination of trace amounts of these metal ions. Stoichiometric ratios were determined for the iron(II) chelates... | 18,962,451 |
A method for removal of chloride interference in determination of aluminium by atomic-absorption spectrometry with a graphite furnace. | Methods for removal of the chloride interferences in determination of aluminium by atomic-absorption spectrometry with a graphite furnace have been investigated. Two mechanisms of chloride interference have been established. The first arises from co-ordination of the chloride to aluminium. This interference can be remo... | 18,962,452 |
Titration of some thiazine dyes with TiCl3 at room temperature. | Methylene Blue and some other thiazine dyes are titrated at room temperature visually and potentiometrically in presence of 0.005-0.1N oxalic acid. The effect of oxalic acid on the conditional potentials of the Ti(IV)/Ti(III) couple is presented. | 18,962,457 |
Study on Semi-Glycinecresol Red complexes with bivalent metal ions. | Semi-Glycinecresol Red (SGCR or H(3)SGCR) was purified by means of chromatography on cellulose and by cation-exchange. A potentiometric, spectrophotometric and ESR study on the complex formation equilibria of several bivalent metal ions with SGCR was performed. The acid-base and metal-ligand stoichiometries were determ... | 18,962,471 |
Multiparametric curve fitting-IV Computer-assisted estimation of successive dissociation constants and of molar absorptivities from absorbance-pH curves by the DCLET program. | The program DCLET evaluates the dissociation (or protonation) constants and molar absorptivities (HjL) of all light-absorbing species (HjL), (j = 0,..., J) of a polyprotic acid (HjL) by a non linear regression of the function A = f(pH; pK (a), (HjL)), i.e., by multiparametric curve fitting. The three specific subroutin... | 18,962,488 |
Determination of small concentrations of HCl by derivative formation-a problem and how it might be solved. | In the investigation of methods for the determination of chloride three reactions for making derivatives of HCl have been developed. The individual problems which arise for the different methods are discussed. The reactions are reaction of CrO(3) with HCl to give CrO(2)Cl(2), reaction of epoxides with HCl to produce al... | 18,962,512 |
Correlation between flame geometry and the absorbance of some elements in the presence of organic solvents. | The correlation between the changes in flame geometry and the sensitivity of atomic-absorption determination of silver, copper, iron and lead in the presence of various solvents (water, ethanol, n-propanol, methyl acetate, ethyl acetate and acetone) has been investigated. The flame geometry was studied by the Schlieren... | 18,962,525 |
[Not Available]. | The authors describe the identification by infrared microtechniques (multi attenuated total reflexion) of the residues of eleven substituted ureas used as herbicides, after separation by thin-layer chromatography. The limitations of the method and the interferences from extracts of natural waters are discussed. In the ... | 18,962,532 |
Precipitation of uranium from low-level liquid wastes. | A method for the recovery of uranium from low-level liquid wastes is described. Uranium(VI) is reduced to uranium(IV) in sulphuric-phosphoric acid solution with iron(II). The uranium(IV) is precipitated as the double duoride with sodium. The uranium content of the filtrate is in the low ppm range. Possible modification... | 18,962,538 |
Photometric reagents for alkali metal ions, based on crown-ether complex formation--III. 4'-picrylaminobenzo-15-crown-5 derivatives. | An extraction study of alkali metal cations has been made with crown-ether reagents, 4'-picrylaminobenzo-15-crown-5 derivatives (HL). On dissociation in alkaline medium, the orange HL gives the blood-red anion L(-) and extracts alkali metal ions into chloroform as coloured complexes of composition ML.HL or ML. The ease... | 18,962,544 |
An investigation of a flameless atomic-absorption method for determination of aluminium, calcium, iron and magnesium in sewage sludge. | The methods currently used for the determination of aluminium, calcium, iron and magnesium in sewage sludge are time-consuming. A rapid flameless atomic-absorption procedure, utilizing homogenization of diluted samples as the only pretreatment, has been compared with wet and dry analytical methods followed by flame ato... | 18,962,545 |
Dual-wavelength spectrophotometric determination of cadmium with cadion. | Cadmium has been determined by dual-wavelength spectrophotometry with cadion, p-nitrobenzenediazoaminobenzene-p-azobenzene, and a non-ionic surfactant, Triton X-100. Cadion and its cadmium chelate are dissolved in a micellar solution of the surfactant. The absorbance difference at the wavelength of maximum absorption o... | 18,962,550 |
Determination of sulphur by electrolytic hydrogenation. | Certain sulphur compounds such as thiosulphuric acid, polythionic acids, thiocyanic acid, thioureas, thioamides and 2-mercapto-acids are readily electrolytically hydrogenated in 1N sulphuric acid to form hydrogen sulphide which is absorbed in potassium hydroxide solution and titrated with o-hydroxymercuribenzoic acid i... | 18,962,557 |
Polarographic determination of ampicillin in capsules and tablets. | A new polarographic method is used for quantitative analysis of ampicillin dosage forms. The electroactive product is formed by acidic hydrolysis of ampicillin. It gives a well-developed reduction wave with half-wave potential of -0.91 V vs. SCE. The proposed method has good precision. A major advantage is the selectiv... | 18,962,573 |
Hydroxide complexes of lanthanides--II: samarium(III) in perchlorate medium. | From the precipitation borderline in the pM'-pH diagram, determined experimentally under CO(2)-free conditions, the stability constants of the mononuclear and polynuclear species of samarium hydroxide have been established. The values found are log beta(1) = -7.5, log beta(2) = -15.0, log beta(3) = -22.7, log beta(4, 3... | 18,962,586 |
[Acidites et complexes des acides (alkyl-et aminoalkyl-) phosphoniques-IV: acides aminoalkylphosphoniques R(1)R(2)N(CH(2))(n)CR(3)R(4)PO(3)H(2)]. | The acids under study differed from one another in length of the carbon chain [N + H(3)(CH(2))(n)PO(3)H(-) for n = 1, 2, 3], substitution on the nitrogen atom [R(1)R(2)N + HCH(2)PO(3)H(-) for R(1) = H; R(2) = Me, Et and R(1) = R(2)= Me, Et] or extent of branching on the carbon atom adjacent to functional groups [N + H(... | 18,962,590 |
The influence of pH and complex formation on the ASV peaks of Pb, Cu and Cd. | The effects of pH, electrolyte composition and complex formation on the size and position of the ASV peaks of Pb, Cu and Cd have been systematically evaluated, with an instrument equipped with a mercury thin-film electrode and by applying a linear ramp voltage scan. The peak heights change with pH and the magnitude of ... | 18,962,604 |
Investigations on the usefulness of tiron in separation of metal ions on the macroporous anion-exchanger amberlyst A-26. | The possibility of application of a sulpho-derivative of an aromatic organic complexing agent-tiron-for separation of cations on the macroporous anion-exchanger Amberlyst A-26 has been investigated. Comparative results obtained with Amberlite IRA 400 have proved the macroporous exchanger to be the more useful. The depe... | 18,962,605 |
Titration of phosphonic acid derivatives in mixtures. | An analytical procedure is described for the determination of the weak acids phosphonomethyliminodiacetic acid and phosphonomethyliminoacetic acid in their mixtures, and the dissociation constants of phosphonomethyliminoacetic acid are reported. | 18,962,615 |
Electrochemical detectors for flowing liquid systems. | A review of the theory, applications, and advantages and disadvantages of the major types of electrochemical detectors in flowing systems is presented in this report. | 18,962,627 |
Determination of thallium and lead in cadmium salts by anodic stripping voltammetry with addition of surfactants to suppress the cadmium peaks. | Conditions have been found which make possible the determination of thallium and/or lead in cadmium and its salts without preliminary separation. The electrochemical activity of the cadmium, which usually interferes in the determination of thallium, is inhibited by the addition of 0.01% of polyethylene glycol of M.W. 4... | 18,962,633 |
Using orthogonal array to obtain gradient liquid chromatography conditions of enhanced peak intensity to determine geniposide and genipin with electrospray tandem mass spectrometry. | The conditions to determine geniposide and genipin using gradient liquid chromatography-tandem mass spectrometry (LC-MS/MS) via electrospray ionization were obtained using fractional factorial experimental design approaches, guided with Taguchi orthogonal arrays to enhance peak intensity. Geniposide, the major iridoid ... | 18,962,644 |
Determination of decamethylcyclopentasiloxane in river water and final effluent by headspace gas chromatography/mass spectrometry. | A method is described for the analysis of decamethylcyclopentasiloxane (D(5)) in river water and treated waste water using headspace gas chromatography/mass spectrometry. Internal standard addition to samples and field blanks was carried out in the field to provide both a measure of recovery and to prevent any exposure... | 18,962,646 |
Conventional and narrow bore short capillary columns with cyclodextrin derivatives as chiral selectors to speed-up enantioselective gas chromatography and enantioselective gas chromatography-mass spectrometry analyses. | The analysis of complex real-world samples of vegetable origin requires rapid and accurate routine methods, enabling laboratories to increase sample throughput and productivity while reducing analysis costs. This study examines shortening enantioselective-GC (ES-GC) analysis time following the approaches used in fast G... | 18,962,648 |
Water analysis by spark-source mass-spectrometry after preconcentration on activated carbon. | For trace analyses of environmental waters, spark-source mass-spectrometry has been combined with a preconcentration procedure involving chelation of the dissolved trace elements with oxine and subsequent adsorption of the oxinates and naturally occurring organic and colloidal metal species onto activated carbon. The a... | 18,962,695 |
[Not Available]. | The proton concentration resulting from the dissociation of a moderately strong dibasic acid can be precisely determined by means of an acid-base indicator by differential spectrophotometry. The dissociation constants are then calculated by linear regression of the appropriate function. The method was tested on the fir... | 18,962,700 |
Silver-reductor method for determination of iron in iron ores and iron-ore sinters. | A new technique for the quick dissolution of iron ore, magnetite and sinter products has been developed. The sample is dissolved with thioglycollic acid and hydrochloric acid, the excess of thioglycollic acid is oxidized, and the iron is reduced in the silver reductor. | 18,962,704 |
Construction of a liquid-membrane type periodate ion-selective electrode and its application to the potentiometric titration of alpha-diols and alpha-amino-alcohols. | The construction of a liquid-membrane type periodate ion-selective electrode and its application to the potentiometric titration of alpha-diols and alpha-amino-alcohols are described. The ion-pair of periodate anion with Capriquat (tri-n-octylmethylammonium chloride), is easily extracted into nitrobenzene, and this ext... | 18,962,713 |
A new spectrophotometric method for differentiating mononuclear and polynuclear complexes and for determining their extraction constants. | A new spectrophotometric method is proposed for differentiating mononuclear and polynuclear complexes as well as for determining the extraction constant K*(e) of any complex A(m)B(n). The method is based on the effect of dilution on the degree of dissociation of the complex. The precision of log K*(e) is +/- 0.03 when ... | 18,962,723 |
Age at onset influences on wide-ranged clinical features of sporadic amyotrophic lateral sclerosis. | To profile the detailed clinical features of sporadic amyotrophic lateral sclerosis (ALS) on large-scale samples in Japan. We assessed the clinical features of sporadic ALS patients in Japan, based on the nationwide registration system of the Ministry of Health, Labor and Welfare of Japan. We described 3,428 new cases ... | 18,962,725 |
Statistical adjustment of parameters for potentiometric titration data. | The paper deals with the statistical problem of adjusting parameters to the experimental data from potentiometric titrations. The parameters to be refined are, first, the value of the stability constant of the titration reaction, and, second, the equivalence volume. The paper discusses the selection of the error variab... | 18,962,730 |
Determination of lanthanides with m-toluidinyloxamic acid. | m-Toluidinyloxamic acid is shown to be about as efficient as the para isomer as a gravimetric reagent for La, Pr and Nd. Conditions have been established for the determination of these lanthanides in presence of a number of metal ions. | 18,962,734 |
Estimation of individual thio-salts and sulphate in flotation mill solutions. | This paper presents methods found to be suitable for the determination of thio-salts and sulphate in flotation mill solutions. Thiosulphate, tetrathionate and trithionate are estimated spectrophotometrically after cyanolysis. A modified iodimetric procedure is used for sulphite and a titrimetric method for direct deter... | 18,962,735 |
Derivatives of 2-thiohydantoin as spectrophotometric analytical reagents-II Condensation at C-5 with aromatic non-pyridine aldehydes. | The synthesis, characteristics, properties and reactions with metallic ions of six aromatic derivatives of 2-thiohydantoin have been studied. The reagents exhibit two pK values in aqueous solution, and with Pd(II), Au(III), Ag(I) and Hg(I) and (II), especially with the first, form stable complexes with molar absorptivi... | 18,962,740 |
Amperometric determination of 2-benzothiazole sulphenamide accelerators. | A simple method for the amperometric estimation of N-cyclohexyl-2-benzothiazole sulphenamide, N-dicyclohexyl-2-benzothiazole sulphenamide, 2-(morpholinothio)benzothiazole and N-tert.-butyl-2-benzothiazole sulphenamide is reported. The results are obtained within 5 min and are correct within +/- 2.0%. | 18,962,755 |
Ion-exchanger colorimetry-VI Microdetermination of nickel in natural water. | Ion-exchanger colorimetry with 1-(2-pyridylazo)2-naphthol (PAN) has been developed for the determination of nickel at the mug/l. level in natural water. With 1 litre of sample the detection limits are 1.3 x 10(-9)Mi.e., 0.077 mug/l. for fresh water and 5.8 x 10(-9)Mi.e., 0.34 mug/l. for sea-water. The distribution rati... | 18,962,762 |
Properties of cis- and trans-bis(crown ether)s for complexation and extraction of alkali metal picrates. | The properties of cis- and trans-bis(crown ether)s containing benzo-15-crown-5 or benzo-18-crown-6 units as complexants and extractants for alkali metal picrates have been studied. The optical spectra suggest that the cis-bis(crown ether)s can form intramolecular 2:1 crown ether unit/cation complexes with particular me... | 18,962,783 |
Standardization of EDTA by spectrophotometric titration, with metallic copper as standard. | The standardization of EDTA against electrolytically pure copper is described. The copper is dissolved and titrated spectrophotometrically with EDTA at pH 5.0 without an indicator. A relative standard deviation of 0.009% was achieved. | 18,962,786 |
Photometric determination of copper with N-(dithiocarboxy)sarcosine after preconcentration with amberlite xad-2 resin. | The copper(II) chelate of N-(dithiocarboxy)sarcosine (DTCS) is sorbed on a column of Amberlite XAD-2 resin from a pH-7 phosphate solution (0.1M) and stripped with a pH-9.0 ammonia solution (0.2M) in 60% methanol. The absorbance of the eluted chelate is measured at 432 nm against water. Sodium nitrilotriacetate, sodium ... | 18,962,798 |
The determination of oxygen in powdered tungsten carbide by reducing fusion: Suppression of primary carbon dioxide, selection of working conditions and adsorbed-moisture effects. | A method for the reducing fusion determination of oxygen in powdered tungsten carbide is described. It is shown that, as theory predicts, tungsten carbide may evolve its oxygen content not only as carbon monoxide but also as perceptible quantities of carbon dioxide. An easy suppression of this primary carbon dioxide, a... | 18,962,814 |
Laboratory microcomputer system for the development of microcomputer-controlled analytical instrumentation. | Researchers in analytical procedures can acquire greater control over their experimental parameters, procedures and the mathematical operations used to manipulate and evaluate their data, by incorporating microcomputer technology into their laboratory instrumentation. A hybrid microcomputer system has been assembled to... | 18,962,831 |
Coulometrically generated copper(II) in acetonitrile as an analytical oxidant. | Copper(II) was generated at 100% current efficiency from solutions of copper(I) perchlorate in acetonitrile. Micromole quantities of ferrocene and several alkyl-substituted ferrocenes were determined with high precision and accuracy. Hydroquinone and several thiols, on the other hand, could not be determined because of... | 18,962,837 |
Mixed-ligand complexes of iron and hydroxy-1,10-phenanthrolines. | The half-wave potentials of all of the possible tris-complexes formed between iron(II) and 1,10-phenanthroline (A), 4-hydroxy-1,10-phenanthroline (B), and 4,7-dihydroxy-1,10-phenanthroline (C) have been measured at a rotated platinum electrode. Values on the hydrogen scale are 1.06 V for A(3)Fe(II), 0.78 for A(2)B, 0.5... | 18,962,841 |
Liquid-liquid extraction of osmium thiocyanate with hexamethylphosphoramide and direct spectrophotometric determination in the organic phase. | The use of hexamethylphosphoramide (HMPA) in the osmium-thiocyanate system makes the method more sensitive and selective. The blue colour formed by osmium(VIII) with thiocyanate in 1.5M hydrochloric acid is intensified in the presence of HMPA and the complex becomes readily extractable into chloroform. The colour syste... | 18,962,858 |
Effect of cumulus cell coculture and oxygen tension on the in vitro developmental competence of bovine zygotes cultured singly. | The customary practice in bovine in vitro embryo production (IVP) is to handle oocytes and embryos in groups; although there are several reasons for establishing an IVP system for individual embryos that allows for following a single oocyte from retrieval through development to the blastocyst stage. To date, reports of... | 18,962,875 |
Room-temperature phosphorescence and fluorescence of nitrogen heterocyclics adsorbed on silica gel chromatoplates. | The room-temperature phosphorescence of benzof]quinoline and phenanthridine has been enhanced considerably by spotting HBr-ethanol solutions of the compounds onto silica gel chromatoplates. Acridine showed no room-temperature phosphorescence but gave very strong fluorescence on silica gel chromatoplates. The analytical... | 18,962,881 |
Aquametric submicro determination of water content of biopolymer preparations and its application in deriving hydration isotherms. | A rapid aquametric submicro method is proposed for determining 10-100,mug of bound water in 20-60 mug amounts of biopolymers. This method has been applied in deriving isotherms of water-vapour adsorption by biopolymer preparations (proteins, tRNA), in a dynamic mode requiring only 5 mg of the substance. The BET equatio... | 18,962,884 |
Short leucine-rich glycoproteins of the extracellular matrix display diverse patterns of complement interaction and activation. | The extracellular matrix consists of structural macromolecules and other proteins with regulatory functions. An important family of the latter class of molecules found in most tissues is the small leucine-rich repeat proteins (SLRPs). We have previously shown that the SLRP fibromodulin binds directly to C1q and activat... | 18,962,898 |
Structural features of T cell receptor variable regions that enhance domain stability and enable expression as single-chain ValphaVbeta fragments. | The variable (V) domains of antibodies and T cell receptors (TCRs) share sequence homology and striking structural similarity. Single-chain antibody V domain constructs (scFv) are routinely expressed in a variety of heterologous systems, both for production of soluble protein as well as for in vitro engineering. In con... | 18,962,897 |
Fundamental investigation of thermal properties of rare-earth beta-diketonates. | The thermal properties of the rare-earth chelates of Htfa (trifluoroacetylacetone) and Hhfa (hexafluoroacetylacetone) have been investigated. Thermogravimetric curves were obtained by heating samples in the injection chamber of a gas chromatograph, both in an atmosphere of helium, and of helium containing ligand vapour... | 18,962,924 |
Hydrodynamic modulation voltammetry. | Highly efficient background-correction techniques applicable to voltammetric methods of trace analysis can be developed by modulating the convection rate of the solution at a solid electrode surface. The theoretical aspects, advantages, disadvantages, and analytical applications of the various batch and flow approaches... | 18,962,941 |
Silmization of stainless-steel frits for use in trace metal analysis by high performance liquid chromatography. | A simple method has been developed to minimize the interferences related to the metal parts of an analytical system used for trace metal analysis by HPLC. This is accomplished by blocking the exposed metal surfaces with an organosilane. The effect of the silanized stainless steel frits has been demonstrated by injectin... | 18,962,951 |
A simple method for the determination of benzo[a]pyrene and benzo[k]fluoranthene in a mixture. | Atmospheric particulate matter is routinely analysed for the concentration of the carcinogen benzo[a]pyrene (BaP). Benzo[k]fluoranthene (BkF) has identical spectral characteristics and interferes in the fluorimetric estimation. A simple method for the determination of BaP in the presence of BkF is described. Based on q... | 18,962,966 |
Indirect method for determining silicon and phosphorus, and analysis of cuban laterites. | A method has been developed for determining silicon and phosphorus in minerals with high iron content, the method being based on the formation, extraction and stripping of molybdenum heteropoly acids and determination of molybdenum after decomposition of the complexes in the aqueous phase from the stripping. | 18,962,977 |
Some aspects of room-temperature phosphorescence in liquid solutions. | Experimental requirements for room-temperature phosphorescence measurements in liquids (RTPL) are discussed. Phosphorescence quantum yields and triplet lifetimes of some brominated naphthalenes and halogenated biphenyls at 77 K in 2-methyltetrahydrofuran and at room temperature in hexane are reported and compared. Surp... | 18,962,992 |
Dual-wavelength spectrophotometric determination of copper in sea-water with alpha,beta,gamma, degrees -tetrakis(1-methylpyridinium-4-yl) porphine. | Copper has been determined by dual-wavelength spectrophotometry with alpha,beta,gamma, degrees -tetrakis(1-methylpyridinium-4-yl) porphine (TMPyP). The difference in absorbance at the Soret band of the copper complex (423 nm) and that of TMPyP (446 nm) was measured. Copper in a coastal sea-water sample was preconcentra... | 18,963,002 |
Indirect spectrophotometric determination of sulphide with the ternary complex system Ag(I)-phen-BPR. | Trace amounts of sulphide can be determined from its effect on the ternary complex system of Ag(+), Bromopyrogallol Red (BPR), and 1,10-phenanthroline (phen). Sulphide in the range 5-120 ng/ml causes a decrease in absorption, that is a linear function of the concentration. Common metal ions such as Na(+), K(+), Ca(2+),... | 18,963,019 |
Hydrophobic indicators for two-phase titrations and their application to the determination of silver and pentachlorophenol. | The hydrophobic dyes tetrabromophenolphthalein ethyl ester and 2,6-dichlorophenolindo-phenol are proposed as visual indicators for two-phase titrations. The aqueous phase is colourless throughout the titration and these indicators make it possible to detect the end-point of the titration by the colour of one or the oth... | 18,963,021 |
Evidence of competitive mechanisms during oxidation of CS(2)N(-)(3) by permanganate ion in alkaline solution. | The oxidation of the 1,2,3,4-thiatriazole-5-thiolate ion, CS(2)N(-)(3), by permanganate ions in alkaline medium has been investigated over a wide range of oxidant concentrations. With a moderate excess of permanganate ion a 17-electron reaction takes place, yielding sulphate, nitrogen and carbon dioxide. With a high pe... | 18,963,024 |
Arsenic speciation by ion-exchange separation and graphite-furnace atomic-absorption spectrophotometry. | As(III), As(V), monomethylarsenic acid (MMA) and dimethylarsenic acid (DMA) were determined by graphite-furnace atomic-absorption spectrophotometry after separation of the species by ion-exchange chromatography. The detection limits (ng/ml) were DMA 0.02, MMA 2.0, As(V) 0.4 and total arsenic 4.0. As(III) was determined... | 18,963,033 |
[Not Available]. | The reversibility of the determination reaction is the most frequent cause of deviations from linearity of thermometric titration curves. Because of this, determination of the equivalence point by the tangent method is associated with a systematic error. The authors propose a relationship which connects this error quan... | 18,963,035 |
Non-aqueous cerimetric determination of phenylhydrazides. | A non-aqueous oxidimetric method is described for the determination of some carboxylic acid phenylhydrazides with ammonium hexanitratocerate(IV) in acetonitrile. The end-points have been detected visually with chemical indicators (diphenylamine, diphenylbenzidine, Methyl Red, Malachite Green, Janus Green, Gentian Viole... | 18,963,039 |
Auditory steady-state responses to bone conduction stimuli in children with hearing loss. | The auditory steady-state response (ASSR) to air-conduction (AC) stimuli has been widely incorporated into audiological test-batteries for the pediatric population. The current understanding of ASSR to bone conduction (BC) stimuli, however, is more limited, especially in the case of infants and children. There are few ... | 18,963,045 |
Spectrophotometric study on the reactions of iron(II) and iron(III) with Bromopyrogallol Red and hexadecyltrimethylammonium bromide. | Bromopyrogallol Red (BPR) combines with iron(III) in the presence of hexadecyltrimethylammonium bromide (CTMAB) to form an intensely blue complex having a molar absorptivity of 5.20 x 10(4)l. mole(-1).cm(-1) at 635 nm. The complex contains three molecules of BPR co-ordinated to an iron(III) ion, and two molecules of CT... | 18,963,046 |
Addressing, accessing and interfacing peripheral devices to microprocessors. | To utilize the full potential of microprocessors, particularly the small and inexpensive single board systems, for dedicated data acquisition and instrumental system-control functions, it is imperative that researchers have an appreciation of the concepts for addressing, accessing and interfacing peripheral devices to ... | 18,963,061 |
Tissue-type plasminogen activator in the ischemic brain: more than a thrombolytic. | Thrombolysis with tissue-type plasminogen activator (tPA) is used for the treatment of patients with acute ischemic stroke. However, a growing body of evidence indicates that, besides the unquestionable benefit from its thrombolytic activity, tPA also has a deleterious effect on the ischemic brain including cytotoxicit... | 18,963,068 |
Determination of ascorbic acid with o-iodosobenzoate: analysis of mixtures of ascorbic acid with methionine and cysteine or glutathione. | Ascorbic acid has been determined in pure solutions, pharmaceutical preparations, food-stuffs and biological fluids by titration with o-iodosobenzoate, with visual or photometric detection of the end-point, with leuco-2,6-dichlorophenolindophenol plus potassium iodide as indicator. Cysteine and glutathione, which inter... | 18,963,074 |
Analytical reactions of substituted pyrimidines. | Analytical aspects of the chemistry of substituted pyrimidines are reviewed. | 18,963,090 |
Adsorption of the silver ion on soda-glass-I. | A study of the adsorption of silver ions on soda-glass, using a radiochemical technique, has been made, and the effects of time and temperature investigated. A simple kinetic treatment allows estimation of the rate constants for the adsorption and desorption processes. | 18,963,103 |
The total emulation of the intel 8080 instruction set on a mainframe computer. | A software system, ASSIM-8080, has been developed to permit the writing and debugging of Intel 8080 assembly-language programs with the aid of mainframe computers. ASSIM-8080 will assemble, with error checking and error diagnostics, an assembly-language program. If no errors are found in the source code, ASSIM-8080 wil... | 18,963,111 |
Diffuse-reflectance spectroscopy in the infrared. | The theory, and the problems encountered in the development of diffuse-reflectance spectroscopy in the infrared region as an analytical technique, are reviewed. The introduction of Fourier-transform infrared spectrometers has eliminated the difficulty of detecting small scattered intensities, and diffuse-reflectance me... | 18,963,120 |
Development of a high-resolution inductively-coupled argon plasma apparatus for derivative spectrometry and its application to the determination of hafnium in high-purity zirconium oxide. | A high-resolution apparatus for inductively-coupled plasma emission spectrometry (ICPES) has been developed, based on an echelle spectrometer modified for wavelength modulation with a quartz refractor plate. The selectivity of the technique is thus improved, and small amounts of hafnium in high-purity zirconium oxide c... | 18,963,122 |
Observations on 1-phenyl-3-methyl-4-trifluoroacetylpyrazolone-5, a promising extracting agent. | A simple procedure for obtaining 1-phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5 (HPMTFP), a promising metal extractant, is described. Recrystallization studies reveal that only one tautomer can be isolated, sometimes with one molecule of water of crystallization, contrary to reports that a yellow enol and a white ket... | 18,963,127 |
Determination of tungsten in complex sulphide ore concentrates. | Determination of tungsten as the thiocyanato complex after separation as the alpha-benzoin oximate complex has been satisfactorily applied to a standard steel and a complex sulphide ore concentrate containing tungsten associated with considerable amounts of Mo, Cu, Bi, As, Pb, Zn, Fe and Sn. | 18,963,148 |
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