Dimethylglyoxime test

The dimethylglyoxime test for Ni (Section III.27, reaction 8) is applicable in the presence of Co provided excess reagent is added. 

Lev Aleksandrovich Chugaev Dimethylglyoximate test for nickel (first organic spot test reagent for a metal ion)... 

Table 2 Metallic items that resulted in positive dimethylglyoxime test reactions...

Chemical analysis of the suspected involved product(s) represents a fundamental step in the assessment of relevance in occupational allergic contact dermatitis (OACD). Preliminary studies performed by the dermatologist may direct the laboratory work [59]. There are available simple qualitative chemical spot tests that can be performed with little equipment these tests include the dimethylglyoxime test for nickel [60], the... 

The dimethylglyoxime test (Fisher s test) is a simple test for nickel release, and it may be used for jewellery and for other objects that come in direct contact with the skin (Feigl 1972 Fisher 1986). In many countries the dimethylglyoxime test is now commercially available in pharmacies or chemist s shops. 

The test is based on dimethylglyoxime (0.8-1% in alcohol) and ammonia (10%). A cotton-wool-tipped stick with 1-2 drops of each solution is rubbed for up to 30 s against the surface to be tested. A pink-red colour indicates presence of nickel ions. A modified dimethylglyoxime test with increased sensitivity has been developed to correspond to the limit of the Nickel Directive (see below and Table 5) (European Committee for Standardization (CEN) i998d). The modification includes pre-treatment of the surface with... 

The dimethylglyoxime test presents a powerful tool for secondary prevention. People with contact dermatitis due to nickel allergy should limit exposure to nickel, including exposure to nickel-containing personal items, in the workplace and during leisure. In the workplace, nickel-sensitive people with hand eczema and occupational hygienists, etc. may identify objects with which skin contact should be avoided and which should possibly be exchanged for the same object made with other materials. 

Reagent I must be prepared immediately before the investigation. Spot testing is not so accurate or easily carried out as the dimethylglyoxime test for nickel. 

The dimethylglyoxime test for Fe is highly sensitive and selective. If iron is also present, which is almost invariably the case, it is necessary to add citric or tartaric acid before making the solution ammoniacal to prevent the precipitation of ferric hydroxide. On the other hand, the test may be modified to serve as a general test for iron if Fe is previously reduced to Fe by the addition of hydrazine sulfate. 

The formation of the red soluble nickel-dimethylglyoxime compound makes it possible to raise the sensitivity of the dimethylglyoxime test. 

Analysis of zinc solutions at the purification stage before electrolysis is critical and several metals present in low concentrations are monitored carefully. Methods vary from plant to plant but are highly specific and usually capable of detecting 0.1 ppm or less. Colorimetric process-control methods are used for cobalt, antimony, and germanium, turbidimetric methods for cadmium and copper. Alternatively, cadmium, cobalt, and copper are determined polarographicaHy, arsenic and antimony by a modified Gutzeit test, and nickel with a dimethylglyoxime spot test. 

Many compounds capable of chelation have been tested for antimicrobial properties. Those showing positive results include saHcylaldoxime [94-67-7] l-nitroso-2-naphthol [131-91-9] mercaptobenzothiazol [149-30-4], dimethylglyoxime [95-45-4], saHcylaldehyde [90-02-8], cupferron [135-20-6], phenanthroline [66-71-7], isoniazid [54-85-3], thiosemicarbazones, the sulfur analogue of oxine, and numerous antibiotics (qv) including tetracyclines. Whether these compounds function exclusively, partially, or at all by virtue of their abiHty to chelate is open to debate. 

Sponge Nickel Catalyst Dissolve approximately 100 mg of sample in about 2 mL of hydrochloric acid, and dilute to about 20 mL with water. Place 5 mL of this solution into a test tube, add a few drops of bromine water, and make it slightly alkaline with ammonium hydroxide. Add 2 to 3 mL of a 1% solution of dimethylglyoxime in alcohol. An intense red color or precipitate forms. 

Place 0-2 ml test solution containing tin(II) ions (this may consist of the solution obtained from the Group IIB precipitate, reduced with magnesium) in a micro test-tube, acidify (if necessary) with dilute hydrochloric acid, add 0-2 ml 01m iron(III) chloride solution, followed by 0-3 ml 5 per cent tartaric acid solution (to prevent the formation of iron(III) hydroxide), 3 drops dimethylglyoxime reagent, and about 0 5 ml 2m ammonia solution. A red colouration is produced. 

Dimethylglyoxime reagent soluble red iron(II) dimethylglyoxime in ammoniacal solution. Iron(III) salts give no colouration, but nickel, cobalt, and large quantities of copper salts interfere and must be absent. The test may be carried out in the presence of potassium cyanide solution in which nickel dimethylglyoxime (cf. Section III.27, reaction 8) dissolves. 

A useful spot test utilizes the fact that a suspension of red nickel dimethylglyoxime in water when treated with a neutral or acetic acid solution of a palladium salt yields the yellow palladium dimethylglyoxime, which is sparingly soluble in dilute acids. The test is best performed with dimethylglyoxime paper the latter is prepared as follows. Immerse drop-reaction paper in a 1 per cent alcoholic solution of dimethylglyoxime, dry, then immerse again in a solution of 05m nickel chloride rendered barely ammoniacal. The nickel complex precipitates wash thoroughly with water, immerse in alcohol and dry. 

Place a drop of the neutral or acetic acid test solution upon nickel dimethylglyoxime paper, and almost dry by waving over a flame. Immerse the paper in dilute hydrochloric acid until the surface surrounding the fleck becomes white, and then wash the paper with cold water. A pink to red spot remains, depending upon the quantity of palladium present. The acid-stable palladium dimethylglyoxime at the site of the fleck protects the underlying red nickel dimethylglyoxime from attack by the acid. 

If the alternative potassium hydroxide method is employed for the separation of Groups IIA and IIB, the KOH extract may contain As, Sb, Sn, Se, Te, and part of the Mo the residue may contain, in addition to HgS, PbS, Bi2S3, CuS, CdS, and PdS, the gold and platinum partly as sulphides and possibly partly in the form of the free metals. Mo is readily identified by the potassium xanthate or a-benzoin oxime test. The Au and Pt will accompany HgS after extraction with dilute nitric acid upon dissolution in aqua regia, Pt may be identified as the dimethylglyoxime complex in the presence of m hydrochloric acid after the Pb, Bi, Cu, and Cd have been removed. 

Evaporate 1 drop of the test solution and 2 drops concentrated hydrochloric acid in a micro crucible almost to dryness. When cold, add a drop of 0-5m iron(III) chloride solution, followed by 3 drops of a 1 per cent alcoholic solution of dimethylglyoxime, and render the mixture alkaline with ammonia solution. Dip a strip of quantitative filter paper or of drop-reaction paper into the solution. The precipitated iron(III) hydroxide remains behind and the red solution of iron(II) dimethylglyoxime diffuses up the capillaries of the paper. 

Wash the precipitate in thi example,"the nickel dimethylglyoximate can be washed with.cold water until qualitative testing shows.that the wash sgju-. tion is free of chloride ions. a... 

CH3C(NOH)C(CH3)N2HCSNH2. A test reagent for manganese in very dilute solution made from dimethylglyoxime and thiosemicarbazide. 

Note the color of the solution labeled Ni2+. This color is due to the presence of the Ni2+. To 1 drop of this solution, add 5 mL of water and 10 drops of dimethylglyoxime solution. Shake. Now add two to three drops of concentrated ammonium hydroxide and shake again. The formation of a scarlet red precipitate is a positive test for Ni2+. The reaction is... 

Dimethyglyoxime, 0.01 N. Dissolve 0.6 g of dimethylglyoxime (2,3-butanedione oxime) in 500 mL of 95% ethanol. This is an especially sensitive test for nickel, a very definite crimson color being produced. 

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