title stringlengths 0 1.13k | abstract stringlengths 1 15.7k | PMID int64 22 36.5M |
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High frequency titration methods in the investigation of complex formation. | High frequency titration is a valuable tool in the study of complex formation in solutions, and the breaks in the titration curves can be used, in conjunction with the results of other physical methods, to determine the composition of the complexes formed. High frequency titration and other methods have been used to st... | 18,960,079 |
Precipitation from homogeneous solution applied to the drop technique for the study of nucleation. | The technique of precipitation from homogeneous solution has been successfully coupled with the drop technique for study of the nucleation process. | 18,960,081 |
Precise determination of uranium in pure uranium and uranium compounds by constant-current coulomeric titration. | A procedure is described for very precise determination of uranium in high-purity uranium and uranium compounds. Uranium(VI) is reduced in a concentrated hydrochloric acid solution by metallic aluminium in the presence of cadmium ions to uranium(III). This is oxidized to uranium(IV) by protons on addition of an excess ... | 18,960,095 |
[L'application des radioisotopes a la chromatographie sur colonnes de celluloses substituees-IV L'analyse du mercure et du zinc dans le bismuth]. | The Chromatographic behaviour of nanogram amounts of bismuth has been studied by radioisotope techniques on cellobiose, cellulose and seven substituted celluloses. All celluloses in ethyl ether adsorb bismuth, provided that it is as nitrate, and that excess of nitric acid is avoided. Bismuth can be eluted with thiocyan... | 18,960,099 |
Precipitation from homogeneous solution by photochemical action: determination of thorium. | Thorium was precipitated from homogeneous solution by photochemical reduction of periodate to iodate in a solution containing thorium and perchloric acid, by means of a 2537 A low-pressure mercury vapour lamp. For weighing, the precipitate was redissolved, precipitated once as thorium hydroxide, and finally as thorium ... | 18,960,114 |
Rapid microchemical method for the determination of magnesium in biological fluids. | A photometric method for the determination of magnesium in the presence of up to 50-fold excess of calcium is described. A magnesium-Azovan Blue lake is formed, stabilized with polyvinyl alcohol, and the absorbance is measured (Kodak No. 7 filter). The method has been used to determine magnesium in sera. | 18,960,134 |
1-Hydroxy-ethylidene-1,1-diphosphonic acid as a titrimetric agent. | 1-Hydroxy-ethylidene-1,1-diphosphonic acid (HEDPHA) has been proposed as a highly selective titrimetric reagent for thorium. In the presence of 1,2-diaminocyelohexanetetra-acetic acid (DCTA) a soluble binuclear ternary complex, Th(2)(DCTA)(2)(HEDPHA), is formed. The determination of thorium is carried out in a slightly... | 18,960,136 |
Extraction of antimony with tertiary amines. | The extractability of antimony(III) and (V) with tridodecylamine from various aqueous solutions is reported. Extraction from nitric and hydrofluoric acid solutions is low, but extraction from sulphuric, hydrochloric and hydrobromic solutions is high. Antimony-(III) can be separated from antimony(V) in 7M nitric acid or... | 18,960,147 |
Kinetics of the precipitation of palladium dimethylglyoximate from homogeneous solution. | The kinetics of formation of palladium dimethylglyoximate in the post-nucleation and pre-nucleation stages, and the effect of palladium on the reaction of biacetyl and hydroxylamine, have been studied. | 18,960,161 |
APDC-MIBK extraction system for the determination of trace elements in saline waters by atomic-absorption spectrophotometry. | A technique has been developed for the determination of "soluble" cobalt, copper, iron, lead, nickel and zinc in saline waters by simultaneous extraction of their complexes with ammonium pyrollidine dithiocarbamate (APDC) into methyl isobutyl ketone (MIBK) and subsequent analysis by atomic-absorption spectrophotometry.... | 18,960,166 |
Solvent extraction of ammine complexes. | The ammine complexes of zinc and of cobalt(II) can be extracted effectively as the dipicrylaminates or tetraphenylborates by using nitrobenzene as the solvent. | 18,960,177 |
[Not Available]. | A physico-chemical study of the conditions of formation (pH, time, temperature) of dodecatungstates and of their separation with tetraphenylphosphonium chloride is presented. In the iso- and heteropolytungstate series only the anions of the form [XW(12)O(40)]((8-n)-(where n is the oxidation number of X) are precipitate... | 18,960,179 |
Determination of sorbic acid with sodium chlorite. | A new method for the determination of sorbic acid is proposed, using sodium chlorite in hydrochloric add medium as reagent. In these conditions the hydrochloric acid is oxidized to chlorine which adds on to the double bonds of the sorbic acid. The addition is rapid (30-90 sec) and for this reason the determination is m... | 18,960,193 |
Neutron activation analysis by standard addition and solvent extraction: Determination of impurities in aluminium. | A separation scheme based on selective extraction in conjunction with the standard addition technique has been developed for the determination of impurities in aluminium by neutron activation. Preliminary investigations have been carried out on the extractability of Sc, Co, Hf, Fe, Sn, Cd, Zn, Ag, Cr, Ce, Cs and Rb by ... | 18,960,206 |
A critical review of methods of isolating and separating the noble metals-III Chromatography, precipitation and fire assay. | This review deals with the chromatographic, precipitation and fire-assay methods of separating the seven noble metals, published subsequent to the previous reviews and prior to January 1966. The noble metal species present in solution are discussed in so far as they relate to separation and determination. | 18,960,211 |
Separation and acid equilibria of xylenol orange and semi-xylenol orange. | A mixture of Xylenol Orange (XO) and Semi-Xylenol Orange (SXO) was chromatographed on a cellulose column and ion-exchanged with Diaion SK-1 resin. XO and SXO in the acidic forms were titrated with sodium hydroxide to determine the basicities and the acid formation constants. The absorption spectra of XO and SXO were me... | 18,960,230 |
The meaning of "sensitivity" in trace analysis. | The concepts of the ratio of the change in output signal produced by an increment of a material to be determined to that increment, and the smallest quantity of a material that can be detected "with certainty" are examined. The name "sensitivity" is suggested for the former, and "detectability" for the latter. Mathemat... | 18,960,242 |
Complexation reactions of dithiocarbamates. | The complexation reactions of various disubstituted dithiocarbamates are discussed. Special attention is paid to studies of composition and stability of various metal complexes. The conditions of complex formation in solution are treated in terms of side-reaction coefficients. The properties of metal-dithiocarbamate co... | 18,960,244 |
Application of thermoelectric potential measurements in chemical analysis-II Determination of aluminium in iron alloys. | A method is proposed for the rapid determination of aluminium in iron alloys by means of thermoelectric potential measurement. An instrument has been modified, and a method devised for thermoelectro-analytical measurements. The thermoelectric potential of iron-germanium and iron-zinc alloys has been measured, and an at... | 18,960,250 |
Electron spin resonance analysis of the redox indicator variamine blue II. | The oxidation of the redox indicator Variamine Blue in an aqueous medium has been studied by the ESR method. The optimum conditions for the formation of the radical have been determined. The spectra have in some cases shown hyperfine splitting, from which conclusions could be drawn for the nature of the oxidation react... | 18,960,255 |
Determination of critical micelle concentration of non-ionic surfactants by electrocapillary curves. | A method is described for the determination of the critical micelle concentration of non-ionic surfactants by measurement of their effect on the electrocapillary curves for a dropping mercury electrode. The method was compared with the iodine-solubilization, surface tension, and polarographic maximum suppression method... | 18,960,267 |
Gravimetric determination of copper(II) with p-aminobenzoic acid. | A method has been developed for the gravimetric determination of 20-100 mg of copper(II) with p-aminobenzoic acid. Ag, Hg(II), Pb, Al, Fe(II), Bi, Sb(III) and Sn(II) interfere, but Zn, Co(II), Ni and Cd do not. The precipitate can be weighed after drying at 80-100 degrees , or can be ignited to copper(II) oxide at temp... | 18,960,272 |
Volumetric determination of the U/O ratio in uranium oxides. | A method is given for determining the general formula UO(2+x), of sintered uranium dioxide pellets and uranium dioxide powders. Uranium(VI) is reduced by titration with iron(II) ammonium sulphate, after which the total amount of uranium is oxidized by titration with potassium dichromate. The end-points of both titratio... | 18,960,276 |
Determination of (3)H and (85)Kr in aqueous samples by liquid scintillation techniques. | Analytical procedures have been developed for the simultaneous determination of tritium and krypton-85 in aqueous solutions by liquid scintillation techniques. The effects of sample size, amount of water and dye were investigated. | 18,960,285 |
Polarography of molybdenum in aspartic acid solution. | The polarographic behaviour of Mo(VI) in solutions of aspartic acid is reported. In 0.01M acid, two waves are obtained, but at pH 4 only one, and they are diffusion controlled. The determination is possible in the presence of Ni, Cr(VI), W(VI), Mn(II), Co(II), Cu(II) or Th, with an accuracy of 2% in the range 10(-5)-10... | 18,960,293 |
Improved method for the simultaneous absorptiometric determination of cobalt and nickel with quinoxaline-2,3-dithiol. | A new, more stable reagent, S-2-(3-mercaptoquinoxalinyl)thiuronium chloride (MQT), is proposed for the simultaneous absorptiometric determination of cobalt and nickel. It is hydrolysed rapidly to quinoxaline-2,3-dithiol (QDT) in ammonia buffer at pH 10. In the presence of zinc(II), QDT is stabilized by complex formatio... | 18,960,307 |
Complexometric titration of calcium in the presence of larger amounts of magnesium. | A simple and accurate titrimetric determination of calcium in the presence of larger amounts of magnesium is proposed. Calcium is extracted into a small volume of organic solvent as its glyoxal-bis(2-hydroxyanil) complex, and the calcium is titrated with EGTA. The end-point is sharp, and occurs when the red colour of t... | 18,960,309 |
Replacement substoichiometry and its application in activation analysis. | A new method based on the substoichiometry principle has been developed. Instead of substoichiometric amounts of chelating agent, substoichiometric amounts of aqueous solution of a competing metal are used. Theoretical relationships have been derived for this method of substoichiometric replacement. Possibilities for i... | 18,960,317 |
Application of electroluminescence techniques to the determination of aromatic hydrocarbons. | An account is given of the quantitative determination of certain fused-ring aromatic hydrocarbons by means of the electroluminescence induced by application of a small a.c. voltage to inert electrodes placed in a solution of the hydrocarbon in dimethylformamide. | 18,960,335 |
Studies with dithizone--XII. Formation of thiadiazolines by condensation with aldehydes and ketones. | The red colour that develops when mineral acids are added to solutions of dithizone (I; 3-mercapto-1,5-diphenylformazan) in certain samples of dioxan is mainly due to the formation of 2-methyl-3-phenyl-5-phenylazo-1,3,4-thiadiazoline (II) derived in part from adventitious traces of 2-methyldioxalane. A purple compound ... | 18,960,368 |
Determination of part-per-milliard concentrations of mercury by atomic- fluorescence flame spectrometry. | A method is reported for the determination of mercury in the range 0.002-1 microg/ml . Mercury is extracted by dithizone from aqueous solutions into chloroform or isobutyl methyl ketone, the organic solution is aspirated into a hydrogen-oxygen name, and the intensity of atomic-fluorescence of mercury is measured. The m... | 18,960,379 |
Coulometric titration of acids in non-aqueous solvents. | Coulometric titrations of mineral acids, sulphonic acids, carboxylic acids, enols, imides and phenols have been carried out in t-butanol or in acetone with electrically generated tetrabutylammonium hydroxide. Either a potentiometric titration or a visual indicator end-point may be used. The amount of acid titrated rang... | 18,960,387 |
Complexation of uranium by 2-(2-thiazolylazo)-4-methoxyphenol and 2-(2-thiazolylazo)-5-methoxyphenol. | A comparative study has been made of the complexation of uranium(VI) by 2-(2-thiazolyl)-4-methoxyphenol (TAMH) and 2-(2-thiazolylazo)-5-methoxyphenol(TAMR). The complexes are less stable and have lower molar absorptivities than the PAR and TAR complexes but are still useful for determination of uranium. The TAMH chelat... | 18,960,388 |
Activation analysis for selenium and tellurium trace impurities in gallium, arsenic and gallium arsenide. | Destructive and non-destructive activation analysis for selenium and tellurium has been studied. In destructive analysis the selenium and tellurium activities are co-extracted from the irradiated and dissolved matrix elements with dithizone/CCl(4), reagent in a hot-chamber by remote manipulation, then separated from ea... | 18,960,391 |
Potassium-argon dating of the cape granite and a granitized xenolith at sea point. | Ages obtained by potassium-argon dating are reported for the total rock, light mineral fraction and heavy mineral fractions of the Cape Granite, and of a granitized xenolith derived from the Malmesbury sediments. These ages lie between 430 and 554 million years. The heavy mineral fractions from each rock type show the ... | 18,960,415 |
Mass spectra of some bivalent transition-metal ion chelates with pyridylazo phenols and naphthols. | The mass spectra of 2- and 4-(2-pyridylazo)phenol, 2-(2-pyridylazo)-1- and 1-(2-pyridylazo)-2-naphthol and several chelates of these compounds with manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) are discussed. Comparisons are made with the results of solution studies of complex formation of the same che... | 18,960,426 |
Mixing efficiency and instrumental delay effect on recorded kinetic curves. | The effect of reactant addition time and instrumental response time on recorded kinetic curves was considered. The mixing-time. effect was considered for first- and second-order reactions in the case that a simple function of the concentration is measured, and for first-order reactions in the more complex case of non-a... | 18,960,438 |
Spectrophotometric determination of some vic-diols. | Conditions have been established for the determination of mannitol and sorbitol (0.4-14 mug), mannose (3.6-18 mug), myoinositol (1.5-6 mug) and pinacol (11-70 mug) by periodate oxidation. The iodate formed is determined spectrophotometrically by reaction with iodide to form tri-iodide. Exce'ss of periodate is masked wi... | 18,960,443 |
Polarographic investigation of syn-phenyl 2-pyridyl ketone oxime. | The polarographic reduction of syn-phenyl 2-pyridyl ketone oxime to alpha-(2-pyridyl)benzylamine over the pH range 0.78-12.88 is reported. Two waves are observed, both of which are pH-dependent. The complex electrode reaction is discussed and a mechanism advanced to describe the reduction of the oxime group over the pH... | 18,960,447 |
Semipermeable ion-exchange membranes as a preconcentration matrix for trace analysis by electrochemical and neutron-activation techniques. | Ion-exchange membranes were used in conjunction with neutron-activation analysis and anodic stripping voltammetry for the determination of certain trace metal ions. The various parameters which govern the applicability, limitations and sensitivity of the methods were investigated. A new membrane "barrier" electrode ass... | 18,960,463 |
Fluorescence characteristics of inorganic complexes in hydrochloric acid medium at liquid-nitrogen temperature. | A study of the low-temperature fluorescence characteristics of the ions of 55 elements in concentrated hydrochloric acid is reported. The spectral characteristics, effects of hydrochloric acid concentration and time, calibration linearity and sensitivity for Sb(III), Bi, Ce(III), Pb, Te(IV), Tl(I) and Sn(IV) have been ... | 18,960,467 |
Spectrophotometric determination of thallium with 4-(2-pyridylazo)resorcinol and 4-(2-thiazolylazo)resorcinol. | Thallium(III) gives sensitive reactions with PAR and TAR (epsilon = 2 x 10(4) at 520 nm), forming 1:1 complexes at pH approximately 1-2, and a mixture of 1:1 and 1:2 complexes at higher pH values; hydrolysis sets in above pH approximately 3. The stability constants are evaluated. | 18,960,469 |
A simple method for thermoanalysis of evolved gases. | Thermoanalytical processes involving the splitting-off of ammonia, water, halogens, inorganic acids or acid anhydrides can be simply observed by using a specimen-holder in which specific reactions with the decomposition products can be induced. A special glass or quartz double crucible can be used for this purpose; the... | 18,960,470 |
Determination of traces of perchlorate in chlorate solutions. | Perchlorate present in chlorate solutions is determined gravimetrically as tetraphenylphosphonium perchlorate after destruction of chlorate by addition of hydrochloric acid. Interference of Fe(III) and Cr(III) is prevented by complexing with tarartic acid. Replicate analyses of a sodium chlorate solution containing NaC... | 18,960,476 |
Extraction of vanadium into isobutyl methyl ketone. | Because of its advantages in atomic-absorption spectroscopy, isobutyl methyl ketone was chosen as organic solvent for an extraction study on vanadium. Of eight chelating agents which were evaluated for completeness of extraction, ease of use, working pH range, and freedom from interference, cupferron was judged best. | 18,960,477 |
Redox-complexometric determination of iron and cobalt and its application to the analysis of multi-component alloys. | A redox-complexometric determination of iron and cobalt is based on potentiometric titration of iron with EDTA, followed by that of cobalt with iron(III) chloride after addition of 1,10-phenanthroline. This method simplifies the complexometric analysis of more complicated materials. | 18,960,479 |
Studies on methylthymol blue-I Separation and purification of methylthymol blue and semimethylthymol blue. | The metallochromic indicator Methylthymol Blue was purified chromatographically with cellulose and ion-exchange resin columns. The monosubstituted product of the reaction, Semimethylthymol Blue, was also separated and purified, and can also be used for the colorimetric determination of metals. There are not marked diff... | 18,960,484 |
Coulometric assay of the primary standards potassium dichromate and ammonium hexanitratocerate. | The high-precision coulometric titration apparatus of Eckfeldt and Shaffer (Leeds & Northrup Company) has been used for the precision assay of two primary standard materials for oxidation-reduction work. The purity found for NBS 136b Potassium Dichromate. 99.975 %, standard deviation 0.002 %, checks the earlier val... | 18,960,487 |
Collection of traces of metals on carboxy cellulose cation-exchanger. | Carboxy cellulose ("C-cell") is a cation-exchanger based on cellulose and having carboxyl functional groups with pK 3.46 +/- 0.05 at 20 +/- 1 degrees in 1M sodium chloride. The capacity of the exchanger is pH-dependent and the maximum is 0.22 mequiv/g. The capacity is also influenced by the dielectric constant of the m... | 18,960,501 |
Separation of metal ions on tin(iv) tungstate and selenite papers. | Papers impregnated with the inorganic ion-exchangers tin(IV) tungstate and selenite have been shown to be useful for ion-exchange chromatography of several metal ion mixtures, and suitable solvent systems have been developed and evaluated. | 18,960,536 |
Resolution of racemic substances by liquid ion-exchange. | Two optically active liquid anion-exchangers have been synthesized. The separation factors of the enantiomers of sodium (+/-)-mandelate and sodium-N-acetyl-(+/-)-alanate have been determined by batchwise equilibration of aqueous solutions of the salts with chloroform solutions of each of the exchangers. Sodium mandelat... | 18,960,552 |
Oxygen determinations with the aluminium corrosion electrode. | A method for the determination of molecular oxygen in a great variety of liquid and gaseous samples has been developed. The method seems adaptable for control analysis by reason of its sensitivity, rapidity and ease of operation. It gives accurate determinations in the presence of many chemical substances which interfe... | 18,960,568 |
A specific gas chromatographic detector for carbonyl compounds, based on polarography. | The evaluation of a specific gas Chromatographie detector for carbonyl compounds is described. This is based on the polarographic reduction of the Girard T hydrazone derivative which is formed when the carbonyl compound is absorbed in a buffered supporting electrolyte containing the carbonyl reagent. The detector was u... | 18,960,585 |
Solvent extraction-absorptiometric determination of niobium in steels with bromopyrogallol red. | A simple and rapid method is described for the determination of niobium in steel with Bromopyrogallol Red. After dissolution of the sample, niobium is extracted along with iron from concentrated hydrochloric acid into isopentyl acetate. Niobium and iron are stripped into an aqueous solution containing sodium acetate, a... | 18,960,586 |
Polarographic determination of aluminium with alizarin. | The polarographic determination of aluminium as its complex with alizarin in the pH range 9.2-10.1, with the cathode ray polarograph, is described. A solvent extraction procedure is used to eliminate interferences from many other metals. | 18,960,592 |
Effect of pH on concentration of species present in aqueous solutions of carbonyl compounds affected by hydration-dehydration and keto-enol equilibria. | Equations have been derived for hydration-dehydration and keto-enol equilibria of carbonyl compounds, showing the changes, with pH, of individual species present in aqueous solutions. An Egtran computer program has been constructed, so that the pH-variation of individual species for widely varying values of equilibrium... | 18,960,598 |
Applications of digital computers in analytical chemistry-II. | This review deals with applications of digital computers to the evaluation of ionization constants of acids and bases, stability constants of metal complexes, concentrations of equilibrium mixtures, and the solution of rate equations. The use of computers permits systems of greatly increased complexity to be studied, a... | 18,960,616 |
A simple low-power reduced-pressure microwave plasma source for emission spectroscopy. | The construction of a simple low-power microwave plasma source for emission spectroscopy is described. | 18,960,627 |
Activation analysis for mercury in biological samples at nanogram level. | A new method has been devised for determining mercury in samples of biological origin. It is based on complete ignition of the sample in a silica tube, trapping volatile interfering activities such as bromine or chlorine, and selectively adsorbing mercury on a strip of filter paper which has been previously impregnated... | 18,960,634 |
Determination of uranium in rocks by instrumental activation-analysis using epithermal neutrons. | A rapid non-destructive neutron-activation method for the determination of uranium in rocks is described. The method is based on activation with epithermal neutrons and subsequent measurement of the 74 keV gamma-ray of (239)U. Results given for some standard rocks are in good agreement with literature data. The precisi... | 18,960,639 |
A triangular wave form generator. | A simple generator for triangular waveforms is described. It uses two operational amplifiers to give triangular waves between 0 V and a preselected voltage. The scan rate and limit can be varied independently. | 18,960,661 |
Spectrophotometric determination of palladium as tetraphenylarsonium palladium(II) trichlorostannate. | The optimum conditions for the formation of the complex, tetraphenylarsonium palladium(II) trichlorostannate, and its extraction into chloroform have been ascertained and a method has been developed for the spectrophotometric determination of microgram amounts of palladium in the presence of many other elements. | 18,960,666 |
A.C. polarographic determination of unsaturation. | A wide range of olefins can be determined by a.c. polarography of their addition compounds with mercuric acetate. The first step in the reduction of these compounds is a reversible, one-electron process to form the organo-mercury radical and gives a well defined a.c. peak. The optimum conditions for the determination o... | 18,960,677 |
The dissociation constants of alizarin fluorine blue. | Dissociation constants for the analytical reagent alizarin fluorine blue (3-aminomethylalizarin-N N-diacetic acid) have been determined by potentiometric titration at ionic strength 0.1, and are k(1) = 1.28 +/- 0.30 x 10(-5); k(2) = 2.82 +/- 0.24 x 10(-8); k(3) = 3.72 +/- 0.19 x 10(-11); k(4) = 6.39 +/- 0.12 x 10(-12). | 18,960,714 |
Hydrolysis of substituted 8-acetoxyquinolines. | In the absence of metal ions, the hydrolysis of 2-methyl-8-acetoxyquinoline and of 5-chloro-8-acetoxyquinoline follow the same reaction paths as those of the parent ester 8-acetoxyquinoline, including an intramolecular catalysis by the quinoline nitrogen. Unlike the hydrolysis of the other esters, that of the 2-methyl ... | 18,960,716 |
Acid dissociation and metal chelate formation equilibria of some halogenated diphenylthiocarbazones. | The acid dissociation constants (K(a)) of di-p-fluoro-, di-p-chloro-, di-p-bromo-, di-p-iodo-and di-m-trifluoromethylphenylthiocarbazones and the equilibrium formation constants (K(f(1))) of their 1:1 complexes with Co(II), Ni and Zn have been determined at 25 degrees in 50% v v aqueous dioxan at 0.10 M ionic strength.... | 18,960,717 |
Use of tetracyanoplatinate (ii) for the luminescent detection of metalions. | The tetracyanoplatinate(II) (TCP) ion forms insoluble fluorescent compounds with many metal ions. This property has not hitherto been exploited for analytical use. The soluble sodium TCP salt has been applied as a reagent for metal ion detection. Fluorescent precipitates useful for detection of the metal ions were obta... | 18,960,718 |
Determination of vanadium in refractory metals, steel, cast iron, alloys and silicates by extraction of an NBPHA complex from a sulphuric-hydrofluoric acid medium. | A method for determining up to 0.15% of vanadium in high-purity niobium and tantalum metals, cast iron, steel, non-ferrous alloys and silicates is described. The proposed method is based on the extraction of a red vanadium(V)-N-benzoyl-N-phenylhydroxylamine complex into chloroform from a sulphuric-hydrofluoric acid med... | 18,960,775 |
Indirect determination of fluorides by the EDTA titration of samarium. | Fluorides are determined by the back-titration of excess of samarium with EDTA to the canary yellow end-point of Methylthymol Blue. The fluoride is precipitated and digested in a solution buffered at pH 2.5-3.0 with monochloroacetate buffer. After digestion, the pH is adjusted to 5.6-5.8 with pyridine and the excess of... | 18,960,777 |
Submicro determination of aluminium, bismuth and copper in organometallic compounds. | Methods for the determination of aluminium, bismuth or copper m samples of organometallic compounds weighing 40-110 microg have been developed. Spectrophotometric determination following digestion with nitric and sulphuric acids in a sealed tube is recommended, all results obtained from the analysis of standard compoun... | 18,960,783 |
Naphtho[2,3-d]-2-selena-l,3-diazole as a reagent for the determination of macro to submicro quantities of palladium. | Five analytical procedures, gravimetric, spectrophotometric, radiometric, fluorometric and atomic-absorption, have been developed for the determination of macro to submicro amounts of palladium. The methods are based on the reaction of PdCl(2), with naphtho[2,3-d]-2-selena-l,3-diazole. Analytical conditions such as the... | 18,960,791 |
Extractions with long-chain amines-I Extraction of some metal-xylenol orange complexes into methyltrioctylammonium chloride (aliquat 336-S). | The extraction of traces of metals forming intensely coloured complexes with Xylenol Orange in acidic medium (pH 0-3) has been studied. For such extractions in the presence of sulphates, chlorides and nitrates, a solution of methyltrioctylammonium chloride (Aliquat 336-S) in chloroform has been used. It is shown that i... | 18,960,803 |
Sulphoxides as solvating reagents for the separation of metal ions. | The solvent extraction properties of the following sulphoxides have been evaluated: di-n-octyl sulphoxide (DOSO), bis(n-octylsulphinyl) methane (BOSM), bis(n-octylsulphinyl)ethane (BOSE) and p-tolyl sulphoxide (PTSO). By use of reversed-phase paper chromatography as a qualitative surveying technique, the interactions o... | 18,960,806 |
Pyridine-2-aldoxime and 6-methylpyridine-2-aldoxime as gravimetric reagents for estimation of palladium(II) and uranium(VI). | Pyridine-2-aldoiumc (I) has been found to be a sensitive reagent for the gravimetric determination of palladium(II). From chloride medium, precipitation is complete at pH 3.0-11.0, and in solution containing 1NHNO(3) to pH6.0. The compositions of the precipitates (dried at 130 degrees ) correspond to PdL(2), and PdL(2)... | 18,960,812 |
The complexes of bismuth(III) and nitrilotriacetic acid. | The reaction between bismuth(III) and nitrilotriacetic acid (NTA or H(3)X) has been investigated by ultraviolet spectrophotometry. It has been established that bismuth(III) and NTA form two complexes with compositions bismuth(III): NTA = 1:1 and 1:2. The absorption maxima are at 243 nm (1:1) and 271 nm (1:2), the molar... | 18,960,814 |
Coulometric determination of uranium with a platinum working electrode. | Experimental conditions have been established which enable uranium to be determined coulometrically by the reduction of uranium(VI) to uranium(IV) at a platinum working electrode, by controlled-potential or controlled-potential-limit techniques. The procedure has been used successfully as a subsidiary method in the rou... | 18,960,821 |
Amperometric complex-formation titrations of traces of copper. | Copper has been determined in the submicrogram range by means of a eomplexometric titration with triethylenetetramine (TRIEN), the end-point being detected by following the anodic wave of the chelating agent at a rotating mercury electrode. The influence of the presence of other metals has been investigated both from t... | 18,960,822 |
Optimum physical and chemical conditions for the Methylene Blue method of estimating gaseous sulphide in the environment. | The sensitivity and reproducibility of the Methylene Blue method for gaseous sulphide estimation have been investigated with respect to physical conditions and the concentrations of the reagents, especially sulphuric add. A new design of absorber is proposed to minimize gas-phase loss of the sulphide in the final stage... | 18,960,830 |
Theoretical considerations on the estimation of sample matrix effects in analytical chemistry. | Methods are suggested for evaluating the magnitude of matrix effects on the results of analysis. | 18,960,832 |
Colour changes of chemical indicators-III: colour specification and its accuracy. | The systematic deviations involved in methods for computation of chromaticity co-ordinates have been studied for the specification of indicator colour changes. The weighted ordinale method (Deltalambda = 10 nm) has proved to be satisfactory for evaluation both of C.I.E. and complementary co-ordinates. The C.I.E. colour... | 18,960,882 |
Extraction of tungsten with 8-hydroxyquinoline and some of its derivatives. | The extraction of tungsten by chloroform solutions of 8-hydroxyquinoline(I), 2-methyl-8-hydroxyquinoline(II), 5,7-dibromo-8-hydroxyquinoline(III) and 8-mercaptoquinoline(IV), as a function of the concentration of tungsten and reagent and the acidity of the aqueous phase, has been studied. Evidence was obtained for the ... | 18,960,884 |
Spectrophotometric determination of cadmium in nuclear-grade Zircaloy-2 after selective extraction with a liquid anion-exchanger. | A method is presented for the spectrophotometric determination of cadmium in Zircaloy-2 at the tenths of ppm level. The method involves the extraction of Cd with tri-n-octylamine from 1M HCl, its separation from Fe(III) by scrubbing with tartaric acid, its recovery with 2M sulphuric acid, and the final development of t... | 18,960,901 |
The error in absorption measurements, caused by the use of non-monochromatic light-I Parabolic functions. | The errors in absorption measurements in spectrophotometry, caused by the use of non-chromatic light, have been calculated. Parabolic functions have been assumed for the wavelength-dependence of the intensity of the incident light falling on the cell and of the absorbance of the compound measured. Results of the calcul... | 18,960,907 |
Film stripping voltammetry. | Film stripping voltammetry is a new electrochemical analytical method consisting in concentrating the test substance in the form of a metal or a sparingly soluble compound on the electrode surface and subsequently recording the current for electrodissolution of the deposit. The method has been worked out for determinat... | 18,960,913 |
Spectrophotometric study and analytical application of rare-earth Tiron complexes-II Determination of europium. | The absorption spectra of europium-Tiron complexes in aqueous solution have been measured from 340 to 600 nm. The absorbance at 390 and 420 nm follows Beer's law up to 0.8 mg ml (pH 6.2-6.6). Other rare earths except for cerium(III) did not interfere. The interference of cerium could be removed by addition of ascorbic ... | 18,960,925 |
Extractive spectrophotometric determination of micro and sub-micro amounts of fluoride. | A simple and sensitive extractive spectrophotometric determination of fluoride with the cerium(III)-alizarin complexan chelate has been investigated. The fluoro chelate formed is extracted into n-pentanol containing triethylamine. It is possible to achieve under selected conditions a selective extraction of the cerium(... | 18,960,940 |
Liquid-liquid extraction of lead(II) with tributyl phosphate. | Tributyl phosphate [30% solution in isobutyl methyl ketone (IBMK)] is used for the quantitative extraction of microgram amounts of lead from 3M hydrochloric acid containing lithium chloride (2M) as salting-out agent. It is then stripped from the organic phase with water and determined colorimetrically as its orange-red... | 18,960,950 |
Separation of rhodium from iridium with sodium borohydride and standardization of rhodium(III) solutions. | Of the platinum group metal separations, that of rhodium from iridium is the most difficult. The existing gravimetric methods are too lengthy or make use of organic reagents which ultimately need to be removed before iridium can be determined. The proposed method of separation is rapid, needs no pH control, and easy to... | 18,960,952 |
[Not Available]. | A rapid simple method is described for the determination of carbon in organic compounds. The technique is based on a flash-combustion of the weighed sample (1-3 mg) in a hot empty combustion chamber at 950-1050 degrees and swept by a stream of oxygen at a rate of 80-100 ml min . Together with this flash and dynamic com... | 18,960,978 |
Synergistic effects in the solvent extraction of zinc with salicylaldoxime. | The extraction of zinc with salicylaldoxime was studied. The adduct-forming tendency of zinc salicylaldoximate with pyridine, alpha-picoline, beta-picoline, quinohne and isoquinoline was also investigated. This tendency decreases in the order beta-picoline > pyridine > alpha-picoline > isoquinoline > quinol... | 18,960,989 |
Analytica chimica philatelica. | Notable contributors to analytical chemistry who have been honoured by postage stamps, and the significance of their contributions to the development of analytical chemistry, are reviewed. | 18,960,999 |
Microdetermination of alpha-amino acids by spectrophotometric and titrimetric methods. | Micro-methods for spectrophotometric and oxidimetric determination of alpha-amino-acids are described. They are based on a reaction of the acids with peri-naphthindan-2,3,4-trione hydrate at pH 2.5 to give a red precipitate of dihydroxy-peri-naphthindenone. The red product is dissolved and measured either spectrophotom... | 18,961,019 |
Determination of phosphorus in coke by the oxygen-flask method. | Recent developments in the oxygen-flask technique for determination of phosphorus in coke are described. The existing method was modified by use of the recently proposed potassium antimonyl tartrate catalyst for the ascorbic acid reduction of phosphomolybdate. | 18,961,029 |
Organic analysis by luminescence methods. | This review presents the major features of luminescence methods relating to the estimation of organic compounds in solution. A notation for reporting fluorimetric determinations is proposed. The outstanding factors affecting the fluorescence of solutions are briefly reviewed, and determinations of compounds offering a ... | 18,961,032 |
Statocalcein, a stable Calcein indicator for the EDTA titration of calcium. | A dipotassium pentacalcium dicalcein salt ("Statocalcein") is recommended for use in place of Calcein as an indicator for fluorimetric titration of calcium with EDTA. The new indicator remains stable in solution for long periods (at least 210 days). | 18,961,041 |
The absorption of carbon dioxide in solutions of monoethanolamine. | Infrared, thermogravimetric and analytical results are presented that establish that the ethanolamine salt of 2-hydroxyethylcarbamic acid is formed when carbon dioxide is absorbed in solutions of ethanolamine. | 18,961,043 |
Oxidimetric determination of ascorbic acid with potassium hexacyanoferrate(III) in acid medium. | Conditions have been developed for the titrimetric determination of ascorbic acid with hexacyanoferrate(III), with potentiometric and visual end-points, in sulphuric, hydrochloric or phosphoric acid media. Several organic substances likely to be present in plant tissues do not interfere. | 18,961,044 |
Formation and composition of the precipitates of various metal 8-selenoquinoline complexes. | The effect of acidity on the precipitation of various bivalent metal 8-selenoquinoline and 8-mercaptoquinoline complexes has been systematically studied and compared. The metal ions were Zn(2+), Cd(2+), Pb(2+), Mn2+, Ni(2+), Cu(2+) and Co(2+). Most of the metal ions, except copper(II) and cobalt(II), precipitate as a. ... | 18,961,076 |
Reaction rate methods in analysis. | A review is given of the principles and application of catalytic and reaction rate methods of analysis. | 18,961,109 |
[Détermination de l'or par réaction d'échange de complexes triples à association ionique]. | The principle of exchange of ion-association triple complexes has been used for photometric determination of gold. The effects of Pt, Pd, Tl and other elements have been examined, and conditions established for determination of gold(III) in their presence. | 18,961,124 |
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