Determination of sulphide, polysulphide, thiocarbonates and sulphur by extraction with tributyltin hydroxide, and of thiosulphate by hydrogenation

The methods presented involve the separation of sulphur compounds by means of a hexane solution of tributyltin hydroxide (TBT), followed by titration with o-hydroxymercuribenzoic acid in the presence of dithizone as indicator. Free sulphide is selectively extracted from strongly alkaline solution, whereas the polysulphides and thiocarbonates are extracted at pH 9-10. The polysulphide and thiocarbonate extracts decompose to form TBT-sulphide, sulphur and carbon disulphide. Treatment with sulphite, stannate(II), copper, vinyl cyanide and ethylenediamine, and hydrogenation with zinc and hydrobromic acid have been applied in the course of the analysis. The sulphur is determined by its attack on copper to form copper(I) sulphide which is subsequently dissolved in aqueous potassium cyanide solution and the sulphide separated by extraction.     

Determination of sulphur and total sulphur dioxide in wines by an ICP-AES method

Sulphur contents of the original sample and the sample free from sulphur dioxide were determined by ICP-AES following nitric acid digestion under high pressure (using PAAR HPA equipment), and the total sulphur content was calculated from the difference between the results obtained. With the aim of preparing a sample free from sulphur dioxide, bound sulphur dioxide was released by sodium hydroxide, then after acidifying by phosphoric acid, boiling was carried out. Relative standard deviations of the results obtained for total sulphur, the sulphur without S(IV) and total sulphur dioxide were lower than 2.5, 3.5 and 5% respectively. Various amounts of sulphur (in the form of Na₂SO₄), added to wine samples, were successfully recovered between 95.5 and 104.9%. Based on comparative analyses performed by a widely accepted classic method, the indirect method developed was found to be adequate for the determination of total sulphur dioxide. The procedure is suitable for serial tests.     

电解氢化物发生原子荧光法测定镉

通过电解氢化物发生技术结合原子荧光光谱仪,采用自行设计的管式电解池,研究了管状阴极材料以及电解质种类、电解条件等因素对Cd的电解还原氢化物发生情况的影响。方法检出限为0.26μg/L,相对标准偏差为3.3%(n=11)。对标准物质海带及几种海产品中的Cd进行了测定,回收率在93%～110%之间。     

Determination of sulphur in petroleum products after sulphur dioxide generation and of sulphur dioxide in air by chemiluminescent flame emission

The determination of sulphur in petroleum products by combustion, concentration of the sulphur dioxide in sodium tetrachtoromercurate solutions and cool flame molecular emission is described. Improvements in burner design and optimization of analytical conditions result in a minimum detectable amount of 6 ng of sulphur. The absorption of sulphur dioxide from air samples and its determination by a similar method gives a detection limit of 1.3 μg SO₂ m^-3.     

Determination of total sulphur in coal by x-ray fluorescence spectrometry

A precise x-ray fluorescence method for the determination of sulphur in coat. The sample is mixed with calcium oxide and active carbon and is gradually heated to 900°C. After coding, lithium tetraborate and lead oxide are added and a prepared. The Pb M_α line is used as an internal standard for the KK_α line. The results for coal have a relative standard deviation of approximately 1% and exhibit.     

Determination of total sulphur in fuel oils by ion chromatography

A method is described for the determination of total sulphur in fuel oils. The oils are burnt in an oxygen flask and the resulting sulphur dioxide is oxidised with hydrogen peroxide to sulphate which is subsequently determined by ion chromatography. With a 50-mg oil sample the limit of detection is 0.007% sulphur. The procedure is simple and has a r.s.d. of 2.7%. Blanks are negligible and the only interferences can be from metal ions that form insoluble sulphates. The method is compared with m.e.c.a, x.r.f. and titrimetric procedures.     

Determination of sulphur functions with iodoso-compounds

Iodoso derivatives, e.g., m- and p-chlorophenyl, m- and p-methylphenyl and p-nitrophenyl-iodosoacetates and o-diacetoxyiodobenzoate, have been thoroughly investigated as oxidants and are proposed as analytical reagents for the determination of thiols, thioureas, isothiocyanates, organic sulphides, disulphides, xanthates, dithiocarbamates, amines and alcohols in aqueous and non-aqueous (acetic acid, acetonitrile, dimethylformamide) media. The error of the determination of thiols is 0.2% thioureas 0.5%, organic sulphides and disulphides 0.4%, isothiocyanates 0.4%, dithiocarbamates 0.4%, and xanthates 0.5%. All the methods are precise to 0.2-0.5%. It is also shown that the properties of the o-derivatives differ markedly from those of the m- and p-derivatives. The o-derivatives contain a 1-substituted 1,2-benzoiodoxilin-3-one ring system. The stability of this system is apparently associated with the size of the five-membered ring; other compounds in which iodine is apparently part of larger rings are less stable. o-Diacetoxyiodobenzoate appears to be the best analytical reagent of the iodoso series. The m- and p-iodosobenzoates are found unsuitable for quantitative oxidation of cysteine.     

Determination of sulphur functions with N-iodosuccinimide

Titrimetric determination of thioureas, thiols, xanthates and dithiocarbamates with N-iodosuccinimide (NIS) is described. The method for xanthate can be applied to carbon disulphide (converted into xanthate with potassium ethoxide). Acidic and non-aqueous solutions of the oxidizing agent are stable. The procedures are rapid and accurate to 0.1% with a precision of 0.2%. Hydrogen sulphide and thiocarbonyl compounds interfere. The behaviour of N-bromosuccinimide and NIS with thiols in aqueous medium is compared. It is shown that iodine is the oxidizing species in both cases. The limitations of iodine as a reagent for thiol determination are discussed. Cysteine, which cannot be determined with iodine, can be determined with NIS. The role of methanol in non-aqueous determination of thiols is discussed. Methanol accelerates the oxidation, which is otherwise slow in acetonitrile medium.     

Molecular emission cavity analysis for organic sulphur compounds after electrolytic generation of hydrogen sulphide

Organic sulphur compounds (thiosemicarbazide and dithioxamide) are determined in the range 5.00–30.0 μg ml^?1. Electrolysis is done between two platinum electrodes in a closed vapour-generation system. Various parameters which affect the procedure are investigated in detail. Other sulphur-containing compounds can be determined with different sensitivities.     

Determination of sulphur in fly ash by instrumental proton activation analysis

A method for the determination of sulphur in fly ash by instrumental proton activation analysis using the³⁴S/p,n/^34mCl reaction was developed. The 2128.5 keV and 3305.0 keV -rays of^34mCl /t=32.0 min/ were measured on a Ge/Li/ -spectrometer, shielded with a lead absorber to attenuate low energy -rays. Irradiation and measuring conditions were optimized. The detection limit for instrumental analysis is 0.3 to 1 mg g^–1 and the standard deviation is cca. 4% for a typical sample.     

Determination of sulphur dioxide by flow injection analysis with amperometric detection

Sulphur dioxide can be determined at a sampling rate of 120 h^?1, with amperometric detection after separation in a diffusion cell with a teflon membrane. At 25°C, the calibration graph shows two linear ranges, between 0.06 and 6 mg l^?1 and 12 and 110 ml l^? sulphur dioxide, with a detection limit of 0.03 mg l^?1. At 50°C, the liner range is 04–5 mg l^?1, with a detection limit of mg of l^?1. The procedure has been applied to the determination of sulphur dioxide in wines.     

Determination of trace contaminants in hydrogenation catalysts by neutron-activation analysis

A neutron-activation method has been developed for the determination of the active constituents and contaminants in hydrogenation catalysts. The active constituents of palladium and nickel catalysts (Pd and Ni) and Zn and Co contaminants present in small amount were determined by a direct instrumental method. A NaI(Tl) scintillator and a Ge(Li) semiconductor connected to a multichannel analyser were used for the measurements. A computer was used to evaluate the γ-spectra. Contaminants present in small amount were also determined by means of a radiochemical separation method based on heterogeneous isotopic exchange on mercury(II) sulphide and zinc sulphide precipitates.     

Determination of some sulphur compounds with N-bromoimides

Two stable oxidants, N-bromophthalimide and N-bromosaccharin are proposed as reagents for the visual and potentiometric titrimetric of thioureas, isothiocyanates, xanthates, dithiocarbamates, thiols, sulphur, thiosulphate, thiocyanate and thiocarbonate. The results are precise within 0.1-0.3%.     

Determination of the sulphur content of geological samples by X-ray fluorescent analysis

Summary The sulphur content of ultramafic and basic rocks is determined by X-ray fluorescent analysis with pressed powder pellets. A commonly marked cellulose powder and wax are taken as diluent. Two analysing crystals, PET and graphite, are compared. The linear calibration curve reaches from 50 ppm to 1.0 weight-%, with a detection limit of 90 and 45 ppm, respectively. If the standard rock is of nearly the same matrix as the examined samples, no calculated matrix correction is necessary.

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Schwefelbestimmung in geologischen Proben durch Röntgenfluorescenz-Analyse

Zusammenfassung Eine Methode zur röntgenfluorescenzanalytischen Schwefelbestimmung an ultrabasischen und basischen Gesteinen wird beschrieben. Die Messung erfolgt an Preßtabletten mit handelsüblichem Cellulosepulver oder Wachs als Verdünnungsmittel. Zwei Analysatorkristalle, PET und Graphit, werden verglichen. Die lineare Eichkurve umfaßt den Konzentrationsbereich zwischen 50 ppm und 1 Gew.-% S. Die Nachweisgrenze liegt bei 90 bzw. 45 ppm, je nach verwendetem Kristall. Bei annähernd übereinstimmender Matrix von Standard- und Analysenprobe ist eine rechnerische Matrixkorrektur nicht erforderlich.

     

Determination of micro-amounts of sulphur in organic compounds by combustion and reduction

Summary A rapid sensitive method for the determination of microgram amounts of sulphur is described. Sulphur (free or combined) in organic substances is oxidised completely in an oxygen atmosphere over a platinum gauze catalyst after a preliminary incomplete combustion in air. The oxides of sulphur are collected on silver gauze at 550°. The oxygen is purged from the apparatus with a stream of nitrogen and then the silver sulphate is heated in a stream of hydrogen to yield hydrogen sulphide which is collected in an alkaline zinc acetate solution and subsequently determined spectrophotometrically by the methylene blue method.The recovery of sulphur in the range 5–40g was 100±5%. The method takes less than 25 minutes for a single determination and is reliable for the determination of as little as1 g of sulphur in all types of organic compounds. Solid, liquid, or gaseous samples may be used.

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Zusammenfassung Eine schnelle, empfindliche Methode zur Bestimmung von Mikrogrammmengen Schwefel wurde beschrieben. Freier oder gebundener Schwefel in organischem Material wird nach unvollständiger Verbrennung in Luft in Sauerstoffatmosphäre über einem Platindrahtnetz vollständig oxydiert. Die Schwefeloxide werden auf Silberdrahtnetz bei 550° gebunden. Der Sauerstoff wird mit Stickstoff aus der Apparatur gespült und dann das Silbersulfat im Wasserstoffstrom zu Schwefelwasserstoff reduziert, der in alkalischem Zinkacetat aufgefangen und dann nach der Methylenblaumethode spektrophotometrisch bestimmt wird.In der Größenordnung zwischen 5 und 10g wird der Schwefel zu 100±5% erfaßt. Eine Einzelbestimmung dauert weniger als 25 Minuten. Für alle Arten organischer Verbindungen, ob fest, flüssig oder gasförmig, eignet sich das Verfahren für die Bestimmung von 1g Schwefel und darüber.

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Résumé On décrit une méthode rapide et sensible pour le dosage de quantités de soufre de l'ordre du microgramme. Le soufre (libre ou combiné) dans les substances organiques est oxydé complètement en atmosphère d'oxygène sur une toile de platine, catalyseur, après une combustion préliminaire incomplète dans l'air. Les oxydes du soufre sont rassemblés sur une toile d'argent à 550°. On purge l'appareil de l'oxygène par un courant d'azote puis le sulfate d'argent est chauffé dans un courant d'hydrogène en donnant de l'hydrogène sulfuré qui est rassemblé dans une solution alcaline d'acétate de zinc et dosé ensuite par spectrophotométrie par la méthode au bleu de méthylène.La récupération du soufre entre 5 et 40g atteint 100±5%. La méthode demande moins de 25 minutes pour un dosage individuel et reste valable pour les teneurs descendant jusqu'à 1g de soufre dans les composés organiques de toutes natures. On peut utiliser des échantillons solides, liquides ou gazeux.

     

Determination of sulphur in silicate and carbonate rocks by wavelength dispersive XRF

Summary A method has been developed for the determination of sulphur in geological materials within the concentration range 0.003–3%. For samples with differing matrices such as geological materials, the fusion method should be employed for X-ray fluorescence flux mixture analysis. The sample is heated with the Li₂B₄O₇ and LiNO₃ (15) in a Pt-Au crucible to 750° C. It has been experimentally verified that the slow heating of the sample in an electric furnace and the presence of an oxidizing agent allows a quantitative binding of all sulphur so that it does not evaporate during subsequent melting of the sample. The glass disc prepared in this way serves not only for the determination of sulphur but also for that of the other major elements. The relative standard deviation of the newly developed method of 4% and the limit of detection 0.003% suffice for the reliable analysis of sulphur in geological materials.

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Schwefelbestimmung in Silicat- und Carbonatgesteinen mit Hilfe der wellenlängendispersiven Röntgenfluorescenzanalyse

Zusammenfassung Das Verfahren zur Schwefelbestimmung in geologischen Materialien wurde für einen Bereich von 0,003 bis 3% ausgearbeitet. Angesichts der verschiedenartigen Matrix wird ein Aufschlußverfahren empfohlen, bei dem die Probe mit einem Gemisch von Li₂B₄O₇ und LiNO₃ (15) in einem Pt/Au-Tiegel bei 750° C erhitzt wird. Durch langsames Aufheizen und durch die Gegenwart eines Oxidationsmittels wird der Schwefel quantitativ gebunden, so daß er während des Schmelzvorganges nicht verdampfen kann. Die so hergestellte Schmelztablette dient neben der Schwefelbestimmung auch zur Bestimmung der übrigen Hauptbestandteile. Die Standardabweichung der Methode beträgt 4%, die Nachweisgrenze liegt bei 0,003%.

     

X射线荧光光谱法测定地质样品中的硫和氟

采用粉末压片制样-X射线荧光光谱法研究地质样品中硫(S)和氟(F)元素的快速测定方法。通过分级过筛实验优化确定样品粒度,探讨样品粒度对测定结果的影响,并进行实际样品和标准物质验证。结果显示,样品粒度为85μm时,经实际样品和标准物质验证,测定结果与化学值和标准认定值相符,且相对标准偏差(RSD)均小于2%。方法具有准确度高、检出限好、测试范围宽、简便快速等优点,能确保样品分析结果的准确性,实现了地质样品中S和F的快速测定。