Spot test detection of some organic reducing agents

A method involving the use of ammonium molybdate and excess 70% perchloric acid is described as a detection test for certain classes of organic reducing agents. Mo(VI) is reduced by the organic reducing agents in the presence of concentrated perchloric acid to molybdenum blue. The procedure distinguishes aliphatic aldehydes from aromatic aldehydes, alicyclic ketones from acyclic and aromatic ketones, unsaturated alicyclic hydrocarbons and unsaturated acyclic hydrocarbons possessing conjugate double bonds from monoolefinic acyclic hydrocarbons and aromatic hydrocarbons, phenols, and saturated alicyclic alcohols from saturated acyclic alcohols.     

Spot test detection of taurine through demasking and pyrolytic effects

A test for taurine is described based on demasking of the inner-complex-bound sulfonic acid group by formaldehyde followed by pyrolysis reactions with mercury (II) cyanide or benzoin. The resulting hydrogen cyanide or sulfur dioxide can be detected in the gas phase by familiar color reactions. All the reactions may lie conducted within the limits of spot test analysis. Microchemical limits of identification are attained.     

Spot test for the detection of iodate in the presence of periodate application to the detection of vic-dihydroxy compounds

Spot tests for the detection of 0.02 mug of iodate in the presence of 45 mg of periodate, and for the detection of 0.1 mug of vic-dihydroxy compounds are described. The tests are based on the iodide-iodate reaction, in the presence of periodate masked by an excess of molybdate.     

Spot test detection of triphenylphosphine (-arsine, -stibine, -bismuthine) and benzoyl peroxide

Summary Triphenylphosphine (and the corresponding arsine, stibine and bismuthine) can sensitively be detected through the formation of a brown polyiodide by the action of iodine vapours. This test fails in a mixture of benzoyl peroxide and small amounts of triphenylphosphine owing to the rapid transformation of the latter into triphenylphosphine oxide. At test for benzoyl peroxide can be based on this behaviour.The procedures for spot tests are described and limits of identification determined.

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Zusammenfassung Triphenylphosphin (desgleichen Arsin, Stibin und Wismuthin) kann nach Einwirkung von Joddampf durch die Bildung von braunem Polyjodid empfindlich nachgewiesen werden. Der Nachweis unterbleibt in einem Gemisch von Benzoylperoxid und kleinen Mengen Triphenylphosphin, da letzteres schnell in Triphenylphosphinoxid übergeführt wird. Darauf läßt sich ein Nachweis von Benzoylperoxid begründen. Die Arbeitsweise für Tüpfelnachweise wird beschrieben und Erfassungsgrenzen angegeben.

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Résumé On peut déceler avec sensibilité la triphénylphosphine (et les arsines, stibines et bismuthines correspondantes) en formant un polyiodure brun par action de vapeurs d'iode. Cet essai ne convient pas dans le cas d'un mélange de peroxyde de benzoyle avec de petites quantités de triphénylphosphine en raison dela transformation rapide de cette dernière en oxyde de triphénylphosphine. Cette réaction peut servir à la recherche du peroxyde de benzoyle. On décrit les procédés d'analyse à la touche et l'on détermine les limites d'identification.

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Dedicated to Prof. Dr.M. Jureek on the occasion of his 60th birthday.     

Spot detection of cerium and cobalt

Summary Sulphosalicylic acid reacts with cerium(IV) at p_H 11±0.5 to give a redbrown complex. With cerium(III) the reaction proceeds only slowly but is markedly accelerated in the presence of cobalt(II). 0.7 g of cerium, and based on its catalytic action, 0.03 g of cobalt can be detected on a spot plate.

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Zusammenfassung Sulfosalicylsäure bildet mit Cer(IV) bei p_H 11±0,5 einen rotbraun gefärbten Komplex. Mit Cer(III) verläuft die Reaktion nur langsam, wird aber durch Gegenwart von Kobalt(II) beschleunigt. Noch 0,7 g Ce und — auf Grund der Katalyse — 0,03 g Co können auf der Tüpfelplatte nachgewiesen werden.

     

Spot test reaction for sulfhydryl groups

2,2'-Dihydroxy-6,6'-dinaphthyldisulfide (DDD) forms a violet product with Fast Blue RR, which precipitates on standing. In presence of sulfhydryl compounds, DDD is reduced and when a monoazo coupling reagent is added, a green fluorescent product is obtained. Amino acids, amino acid derivatives, peptides, weak reducing agents, and water-soluble carbohydrates can be tolerated, but strongly oxidizing reagents or sulfhydryl-blocking reagents interfere. Strongly reducing inorganic compounds give a positive test even in the absence of sulfhydryls. The limit of detection is 5 μg of cysteine or 12 μg of glutathione.     

Spot test for ruthenium(3) andp-phenylenediamine

Summary Para- phenylenediamine gives a spot test for ruthenium(3). Conversely, ruthenram(3) may be used for the detection ofp- phenylenediamine. The test forp- phenylenediamine is very sensitive and almost specific.

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Zusammenfassung p-Phenylendiamine eignet sich als Reagens für Ruthenium(3) und umgekehrt ist Ruthenium(3) ein sehr empfindliches und beinahe spezifisches Reagens fürp-Phenylendiamin.

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Résumé La para-phénylènediamine permet l'analyse à la touche du ruthénium-III. Réciproquement, on peut utiliser le ruthénium-III pour détecter lap-phénylènediamine. L'essai pour lap-phénylènediamine est très sensible et à peu près spécifique.

     

Spot test for bivalent sulphur based on pyrolysis with mercuric cyanide

The test described for bivalent sulphur in organic compounds is based on the finding that hydrogen cyanide can be detected in the gas phase if the sample is heated with mercuric cyanide to 180°. The identification limits range from 5 to 50 μg. An explanation is advanced for the chemistry of the pyrolytic reaction.     

Spot test for sulfites based on the induced oxidation of cobalt-azide solutions

Summary The autoxidation of solutions containing cobaltous and excess azide ions is considerably accelerated by minute amounts of sulfites. Experimental evidence supports the view that the autoxidation of sulfurous acid induces the oxidation of cobalt from the divalent to the tervalent state. A spot test for the detection of sulfites has been developed on the basis of this phenomenon. The test is performed on filter paper. Limit of identification: 0.5g NaHSO₃. Dilution limit: 1100000. Large amounts of thiosulfate ions inhibit the test but can be easily removed.

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Zusammenfassung Die Autoxydation von Kobalt(II)-lösungen, die überschüssige Azidionen enthalten, wird durch kleine Mengen Sulfit erheblich beschleunigt. Versuche deuten darauf hin, daß die Autoxydation der schwefeligen Säure die Oxydation des Co(II) zu Co(III) induziert. Auf dieser Grundlage wurde ein Tüpfelnachweis für Sulfit ausgearbeitet. Er wird auf Filterpapier ausgeführt. Erfassungsgrenze: 0,5g NaHSO₃; Grenzkonzentration: 1100000. Große Mengen Thiosulfat stören den Nachweis, können aber leicht entfernt werden.

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Résumé L'autoxydation de solutions contenant des ions cobalteux et des ions azotures en excès est considérablement accélérée par des quantités de sulfites extrêmement faibles. L'hypothèse de l'induction de l'oxydation du cobalt de l'état divalent à l'état trivalent par l'autoxydation de l'acide sulfureux est confirmée par l'expérience. On a mis au point un essai à la touche pour la détection des sulfites sur la base de ce phénomène. L'essai est effectué sur papier filtre. Limite d'identification: 0,5g NaHSO₃. Limite de dilution: 1100000. La réaction est inhibée par la présence d'ions thiosulfates en quantités importantes, mais ces ions sont faciles à éliminer.

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Part of a communication presented at the XVth International Congress for Pure and Applied Chemistry, Lisbon, September 1956.