Diphenylthiocarbazone extractions with

Diphenylthiocarbazone (dithizone) test dithizone forms complexes with a number of metal ions, which can be extracted with chloroform. The zinc complex, formed in neutral, alkaline or acetic acid solutions, is red ... 

In this method the dithizone solution must be purified immediately before use as follows Extract 10 ml of a stock solution (01 per cent of diphenylthiocarbazone in redistilled carbon tetrachloride) with two 50-ml portions of a solution prepared by diluting 4 ml of lOM ammonium hydroxide to 100 ml with water. Reject the lower layer and, if necessary, filter the combined ammoniacal extracts. Acidify the combined extracts with 1 per cent hydrochloric acid and extract the precipitated dithizone with 100 ml of carbon tetrachloride. Wash the extract with two 10-ml quantities of water and filter the carbon tetrachloride solution through a dry filter paper. 

The nature of the donor atoms in the chelating agent. Ligands which contain donor atoms of the soft-base type form their most stable complexes with the relatively small group of Class B metal ions (i.e. soft acids) and are thus more selective reagents. This is illustrated by the reagent diphenylthiocarbazone (dithizone) used for the solvent extraction of metal ions such as Pd2+, Ag+, Hg2+, Cu2+, Bi3+, Pb2+, and Zn2 +. ... 

Diphenylcarbazide as adsorption indicator, 358 as colorimetric reagent, 687 Diphenylthiocarbazone see Dithizone Direct reading emission spectrometer 775 Dispensers (liquid) 84 Displacement titrations 278 borate ion with a strong acid, 278 carbonate ion with a strong acid, 278 choice of indicators for, 279, 280 Dissociation (ionisation) constant 23, 31 calculations involving, 34 D. of for a complex ion, (v) 602 for an indicator, (s) 718 of polyprotic acids, 33 values for acids and bases in water, (T) 832 true or thermodynamic, 23 Distribution coefficient 162, 195 and per cent extraction, 165 Distribution ratio 162 Dithiol 693, 695, 697 Dithizone 171, 178... 

All observed interferences, except those due to antimony, gold(III) and nitrite, were masked by the pumped addition of 0.02MEDTA (the pH adjusted to 3 with dilute hydrochloric acid) to the sample prior to the reduction step. In the presence of a 5000-fold excess of iron(III), however, depression of the dimethylarsenic signal cannot be completely restored by EDTA (Table 5). Extraction of the sample solution (at pH 2.0) with a 0.005 M solution of dithizone (diphenylthiocarbazone) in dichloromethane overcomes interferences due to silver(I), gold(III), chromium(VI), molybdenum(VI) and tin(II). 

SUB/COR] Subbaraman, P. R., Cordes, S. M., Preiser, H., Effect of auxiliary complexing agents on the rate of extraction of zinc(Il) and nickel(ll) with diphenylthiocarbazone. Anal. Chem., 41, (1969), 1878-1880. Cited on pages 234, 338. 

Diethyldithiocarbamate, pyrrolidin-1 -yldithioformate, and diphenylthiocarbazone (dithizone), as three mercury chelate forming reagents, were used for the preconcentration of ultratrace amounts of inorganic mercury and methyl mercury in silica Cig minicolumn as the solid sorbent. Sample FI online sorbent extraction was coupled with continuous cold vapor atomic absorption spectrometry (CVAAS) for detection. The results showed the superiority of the carbamate type reagents over the dithizone for the online formation and preconcentration of the corresponding mercury chelate. The detection limit was found to be 16 ng/L of mercury. The structures of these organic chelate modifiers are shown in Scheme 17. 

The reagent (e.g, diphenylthiocarbazone, diethyldithiocarbamic acid (2-thenoxy)-3,3.3-tri-fluoroacetone, 8-hydroxyquinoline) must be stable to decomposition, even at very low concentrations in acid and neutral media, and must form an extractable chelate with a sufficiently high value of K (for further useful ligands see [38], [40], [58], [83]). Optimum conditions for substoichiometric extraction are calculated from K, /Cha- and ha-Selectivity of the separation can be improved by use of additional masking reagents [54], [57],... 

Haddock has shown that the yellow bismuth compound formed with potassium iodide can be quantitatively extracted by organic solvents, and in the presence of considerable quantities of highly coloured ions and other interfering metals it is possible to determine very small amounts of bismuth by this method. Lead and thallium in quantities greater than 0 5 mg are the only two elements which interfere seriously other interfering metals (antimony, copper, silver, mercury, tin), especially those which react with soluble iodides, are removed by extracting the bismuth with diphenylthiocarbazone in chloroform before proceeding to the colorimetric determination. 

Dithizone extraction solution. Extract 20 ml of a 0-1 per cent solution of diphenylthiocarbazone in toluene with two 50-ml portions of dilute ammonium hydroxide (50 ml of water containing 1 ml of strong ammonia... 

Sylvester and Hughes published a comparatively rapid method for the determination of small amounts of zinc. Diphenylthiocarbazone in chloroform will extract zinc, copper, mercury, silver, bismuth and cadmium from a solution buffered with ammonium acetate at about pH 4 5. From... 

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