Simultaneous microdetermination of carbon,hydrogen, mercury,chlorine, bromine and sulphur in organic compounds

A simple, reliable method for the simultaneous microdetermination of carbon, hydrogen, mercury, chlorine (or bromine) and sulphur in organic compounds is described. The intermediate storage technique is used. Sulphur and the halogens are absorbed on electrolytic silver and determined gravimetrically or titrimetrically. Mercury is absorbed on gold wire, and is weighed as the metal or desorbed and determined by a mercury-8-hydroxy-quinoline method.     

Organophosphorus compounds: I. Simple,rapid, and reliable method for the simultaneous microdeterminaton of carbon,hydrogen, and phosphorus by the rapid straight empty tube method

A method for the simultaneous microdetermination of C, H, and P is presented. The organophosphorus compound is pyrolyzed in a 80-mm long silica sample capsule using the rapid straight empty tube method. Carbon and hydrogen are determined by conventional gravimetry. Oxides of phosphorus are quantitatively retained on the walls of the capsule. The P₅O₂, uptake is determined gravimetrically for the phosphorus determination.Organophosphorus compounds containing sulfur can also be analyzed following the same procedure. Electrolytic silver, heated at 550 °C, absorbs the oxides of sulfur. The results obtained fall within the acceptable limits of error.     

Determination of traces of hydrogen in fluoro-organic compounds

The determination of traces of hydrogen in highly fluorinated compounds has been studied. Nitrogen and sulphur in the sample interfere slightly in the pyrolytic method of Miller etal. A straightforward combustion method is proposed in which the sample is burned in oxygen over magnesium oxide at 900° and the water formed is determined either gravimetrically or titrimetrically.     

Quantitative extraktive abtrennung von zirkon und titan mit hilfe von n-heptylarsonsäure

Zirconium and titanium can be easily and quickly extracted from ca. 0.5 M hydrochloric, nitric or sulphuric acid by means of n-heptylarsonic acid in chloroform. The metal can be determined gravimetrically, or after some pretreatment, titrimetrically or photometrically. The extraction allows a quantitative separation from a large number of elements. The results obtained for technical products such as alloys and glass are compared with results of standard methods.     

The Solubility of Hydrogen Sulfide in Acetonitrile at 25°C

Abstract

The solubility of hydrogen sulfide in acetonitrile at 25°C has been determined both gravimetrically and titrimetrically to be 0. 528 M. The effects of the presence of water and an electrolyte (LiClO₄) on this parameter are reported.     

The fluorimetric determination of phosphate with thiamine

A method for the microdetermination of sulphur in organic compounds by means of combustion in a flow of oxygen is described. The oxides of sulphur are absorbed and stored on a small silver layer. After completion of the combustion, the oxygen is replaced first by nitrogen and secondly by hydrogen which liberates the sulphur as sulphur dioxide and regenerates the silver layer. The sulphur dioxide can be easily absorbed by dilute hydrogen peroxide and determined by any convenient method.     

The simultaneous microdetermination of chlorine,bromine, and iodine in organic compounds by the oxygen flask method

Summary A method is described which allows the simultaneous microdetermination of chlorine, bromine and iodine following organic decomposition by the oxygen flask procedure ofSchöniger. Sodium borohydride is employed as a reducing agent in the absorbing solution. The sum of halogens is titrimetrically determined in an aliquot of the absorbing solution by means of 0.01N mercuric perchlorate solution. The bromine and iodine are determined in different aliquots after oxidation to halate. Furthermore individual halogens can be determined by this method. The proposed method is simple, rapid, and highly reproducible.

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Zusammenfassung Ein Verfahren zur gleichzeitigen Bestimmung von Chlor, Brom und Jod nach Zerstörung der organischen Substanz im Verbrennungskolben wurde beschrieben. Natriumborhydrid dient als Reduktionsmittel in der Absorptionslösung. Die Summe der Halogene wird mit 0,01-n Quecksilberperchlorat in einem Teil dieser Lösung titriert. Brom und Jod werden in weiteren Teilen nach ihrer Oxydation zu Halogenat bestimmt. Außerdem kann jedes Halogen für sich nach diesem gut reproduzierbaren Verfahren bestimmt werden.

     

Potentiometric determinations with the silver sulfide membrane electrode : Part II. Determination of Sulfur Compounds

A simple, sensitive and fast titrinetric method for sulfur determinations with the silver sulfide membrane electrode is described. Sulfide and sulfate can be determined in one sample. A sensitive sulfate determination is possible after reduction with hydrogen iodide—sodium hypophosphite—acetic acid. Other inorganic sulfur compounds can also be determined. Sparingly soluble metal sulfides can be determined after treatment with strong acid. A reduction with Raney nickel is suitable for the estimation of elementary sulfur and organic sulfur compounds; combustion of the samples in an oxygen flask may be necessary. The methods outlined are applied to the determination of sulfur in steel, some petroleum products and aerosols. When different methods are used, different kinds of sulfur compounds present in an unknown sample can be distinguished.     

Mikrobestimmung von Kohlenstoff und Wasserstoff,sowie von 14C,Tritium und Deuterium im Stickstoffstrom

A microanalytical method for the determination of carbon and hydrogen is described. The procedure involves the combustion of the organic substance in a stream of nitrogen and the oxidation of the decomposition products with oxygen. Halogens and sulphur are absorbed by the combustion catalyst (according to Körbl), whereas nitrogen oxides are reduced on a copper surface. The combustion products, CO₂ and H₂O are determined gravimetrically; in the case of radioactive samples they are appropriately absorbed and counted in a liquid scintillation counter. Strongly quenching singly and doubly labelled samples, which cannot be accurately counted even by modification of the counting device, give equally high radioactive yields (75% for ¹⁴C, 30% for ³H), since counting is not influenced by other gaseous impurities. Deuterium is quantitatively determined by measuring the intensity of the OD-signal at 2500 cm^?1 with an infrared spectrometer.     

Correlation between the Anisotropy of the Electronic Polarizability of Molecules and the Anisotropy of the van der Waals Atomic Radii

A procedure was developed for determining the anisotropy of the van der Waals atomic radii of halogens, hydrogen, oxygen, and sulfur in polyatomic molecules from the experimental characteristics of the anisotropic electronic polarizability of these molecules. The results are consistent with the published van der Waals radii determined by independent procedures.     

Spectrophotometric and gravimetric determination of sulfur in sebacate-base lubricants

Sulfur is determined in sebacate-base lubricants spectrophotometrically and gravimetrically. In the spectrophotometric method, a 0.2–0.3-g sample is treated with mixed acids, magnesium chloride is added, and the solution is evaporated to dryness. The sulfate is reduced to hydrogen sulfide by treatment with a mixture of hydriodic. hypophosphorous, and hydrochloric acids, and the hydrogen sulfide is distilled into ammonia solution. Lead citrate reagent is added and the brownish yellow color of lead sulfide sol is measured. An improved technique and apparatus for the distillation is described. In the gravimetric method, a 5-g sample is treated with mixed acids, antimony and tin are volatilized by treatment with hydrobromic acid, and sulfur is precipitated as barium sulfate. The recommended range of the spectrophotometric method is 0.005–0.15%,and that of the gravimetric method is 0.01–1% sulfur.     

Determination of sulfur in nickel-base alloys and alloy steels by isotope dilution mass spectrometry

An isotope dilution mass spectrometric method has been developed for the precise determination of 3–300 p.p.m. of sulfur in nickel-base alloys and alloy steels. The sample is dissolved in mixed acids, a spike is added, and nitrate ions are removed. Sulfate is reduced with a mixture of hydriodic, hypophosphorous, and hydrochloric acids; the hydrogen sulfide evolved is absorbed in cadmium acetate solution and converted to silver sulfide, which is burned to sulfur dioxide, for the isotope analysis. The relative standard deviation at the 50-p.p.m. level for 1-g samples is less than 3 %.     

Determination of carbon monoxide in metal carbonyl complexes

Carbon monoxide is liberated from carbonyl-containing metal complexes by treatment with various reagents such as pyridinium hydrobromide perbromide in dichloromethane, hydrogen peroxide in acetone, or iodine in pyridine, and oxidized to carbon dioxide by the Schütze iodine pentoxide reagent. The carbon dioxide is determined gravimetrically following absorption on soda asbestos.     

Alkynylated phenazines: synthesis, characterization, and metal-binding properties of their bis-triazolyl cycloadducts

We have synthesized a series of ethynylated phenazines and their bis-triazolyl cycloadducts to serve as metal ion sensors. Binding of metal ions is achieved through coordination to the phenazine nitrogen atom and the triazole ring. To allow metal sensing in aqueous solution, the triazole units are substituted with water-soluble ethylene glycol chains. These phenazine cycloadducts exhibit a selective affinity for binding silver ions. Examination of the halogenated analogues reveals a lowering of the band gap and the corresponding bathochromic shifts in the absorption and emission spectra. The electron-withdrawing properties of these halogens also result in significantly decreased metal-binding activity of the phenazine cycloadducts.     

Ein schwefelselektiver detektor für die flüssigkeits-chromatographie auf konduktometrischer basis

A conductometric procedure for the determination of sulfur in organic solvents is described. The sample is nebulized by a stream of oxygen and the sulfur dioxide produced by combustion at 1300° C is swept into an absorption solution, the increase in conductivity being recorded. The working range is about 1–100 mMol Sl^-1 and the response time about 30s. Interferences of N, P and halogens are discussed. The halogen interference can be eliminated with silver wool, but the sensitivity for sulfur is then reduced.     

Separation of traces of silver from palladium by a surface replacement reaction

An effective method has been developed for the enrichment of silver traces in palladium and of carrier-free¹¹¹Ag formed in it by thermal neutron capture and subsequent β-decay. A replacement reaction occurring between hydrogen atoms absorbed in metallic palladium and cations in aqueous solution has been observed. A new device is proposed for the measurement of hydrogen absorbed by finely divided palladium without the necessity of removing it from the metal. Both palladium and silver ions were quantitatively and selectively deposited in the presence of other cations from hydrochloric acid solutions, whereas the deposition proved to be selective and quantitative for silver from ammoniacal solutions. About 0.4 ppm silver in specpure palladium can be removed by this method. A practical example of a more than 500-fold enrichment of silver traces in palladium is described.     

Determination of silver and mercury bound to polystyrene incorporating isothiourea groups

Mercury and silver were extracted from aqueous solutions by insoluble copolymers of styrene-divinylbenzene incorporating isothiourea groups. The metals were released from the polymers by combustion with a perchloric acid-nitric acid mixture (3:7) and determined titrimetrically. The method was used to measure distribution curves for the two metals from aqueous solutions, and to determine silver in photographic laboratory spent solutions.     

Automatic microanalyzers: IV. Automatic analyzer for rapid microdetermination of chlorine or bromine in organic compounds

An automatic microdetermination of chlorine or bromine in organic compounds is described. The sample is weighed out in an aluminum microbeaker which is dropped into a vertical combustion tube, previously described, the quartz combustion chamber of which is heated up to 1050 °C. A flash combustion in oxygen takes place and the gaseous combustion products are absorbed in a cell with a circulating absorption solution of acetic acid and hydrazine hydrate as a reducing reagent in water.Both halogens give halogenide ions in the absorption solution where they are titrated coulometrically by electrolytic silver ions with an amperometric titration end point. The precision of the results is the same as that obtained with common microanalytical techniques.     

A comparison of the effects of chemisorbed sulfide ions on the electrochemical behavior of gold and silver in thiourea electrolytes

It is shown that, in the case of gold, the catalytic activity of sulfur adatoms is significantly higher in the anodic dissolution of metal than in its deposition. In both processes, the catalytic activity increases with increasing overvoltage. The catalytic activity of sulfur adatoms is considerably lower for silver than for gold both in the metal deposition and dissolution, and it is virtually independent of overvoltage. In the case of silver, the catalytic activity of sulfur adatoms in the electrodeposition is slightly higher than in the metal dissolution. There results are compared with the action of heavy metal adatoms on the dissolution and deposition of gold and silver in the cyanide solutions. It is shown that the above regularities are qualitatively true for both systems. The main distinction is that the catalytic activity of sulfide ions in the thiourea solutions reaches a plateau with increasing surface coverage with sulfur adatoms, whereas the activity of heavy metals passes through a maximum with increasing surface coverage. The results are explained in view of earlier determined regularities of kinetics of electrode processes in these systems and the effect of electrocatalysis on these regularities.     

Rapid detection of Rosa laevigata polysaccharide content by near-infrared spectroscopy

We have investigated surface-enhanced Raman spectroscopy (SERS) spectrum of Omethoate (O,O-dimethyl-S-methylcarbamoylmethylthiophosphate). It is found significant signals in the ordinary Raman spectrum for solid-state Omethoate as well as strong vibrational signals absorbed on the silver sol surface which is prepared by γ-irradiation technique at a very low concentration. Effects of pH and anions (Cl-, Br-, I-) on the adsorption orientation are investigated as well. Two different adsorption mechanisms are deduced, depending on the experimental conditions. The sulfur atom or the sulfur and two oxygen atoms are adsorbed onto the silver sol surface. Among halide ions, Br- and I- are more strongly adsorbed onto the silver sol surface. As a result, the adsorption of Omethoate is less effective due to their steric hindrance.