SU1150532A1 - Gold determination method - Google Patents

Abstract

METHOD FOR DETERMINING GOLD, including translating it into a colored complex compound with dithiopyrilmethane in the presence of perchlorates in an acidic medium, extracting with a solvent, and then measuring the extract, in order to increase the sensitivity and selectivity of the analysis, a mixture of dichloroethane or chloroform is used as a solvent isobutyl alcohol with a volume ratio of 1; O, 25–0.66.

Description

(LS The invention relates to analytical chemistry, namely, methods for determining gold during purification and for obtaining it from natural sources and industrial wastes. Methods are known for the extraction, photometric determination of gold using organic analytical reagents of various structures, of which azo compounds triphenylmethane dyes have acquired the greatest value. and thiols lj. The disadvantages of the known methods are the low sensitivity and selectivity of the analysis. The closest to that proposed for those The essence and achievement of the MiiiM results is the method of extraction-photometric determination of gold using dithiopyrnle methane in the presence of 2 Å aqueous solution of perchlorate at pH of the medium in the range from 4 to 4 N. For sulfuric acid, a complex compound of gold with dithiopirpylmethane is formed. which is extracted in the presence of strong acids anions with chloroform or dichloroethane. The maximum absorption is shifted to the long wavelength part of the spectrum and is observed at 730 nm, the molar extinction ratio of the extracted comp gold excha in the presence of sodium perchlorate is 32400. The highest percentage of gold extraction with dichloroethane or chloroform is observed when carrying out the extraction in the presence of sodium perchlorate. The disadvantages of this method are low sensitivity (up to 0.5 µg / ml gold) and low selectivity with respect to lead ion , cadmium, copper, tungsten, molybdenum, tellurium, antimony, tin, mercury, mol ka (5-20 times the quantity:). When determining small amounts of gold (up to 0.5 μg / ml), the analysis error is high. In addition, when gold is extracted in the form of a complex with dithiopyrilmethane, in the presence of chloroform or dichloroethane in the presence of perchlorates, large losses of gold occur due to adsorption on glass up to 4-6% and at the phase separation line. Extraction is accompanied by clouding of the extracts, which creates additional difficulties in photometric measurements. The purpose of the invention is to increase the sensitivity and selectivity of the analysis. The goal is achieved by the proposed method of determining gold5, which includes transferring it into a colored complex with dithiopyrilmethane in the presence of perchlorates in an acidic medium, extraction with a mixture of dichloroethane or chloroform with isobutyl alcohol at their volume ratio of 1: 0.25-0.66 and subsequent photometric analysis of the extract. The results of a study of various extraction solvents for this analytical system are presented in Table. 1. From table. 1, it is clear that the complex compound of gold is most completely extracted with a mixture of chloroform- (dichloroethane) -isobutanol. At the same time, the loss of gold, which occurs during the extraction with pure solvents due to the loss of 4–5% by adsorption by glass and 20–25% at the interface, drops sharply. The molar ratio of the extracted ternary complexes is increased by 32-34%. The sensitivity increases to 0.1 µg / ml of gold. In other cases, the extraction efficiency is low. The optimum ratios of the extractants in the mixture used for the extraction of the gold dithiopyrylmethane complex were revealed. The optimal conditions for the proposed method are the ratio of extractants of chloroform (dichloroethane) mixed with isobutanol, equal to 1: 0.25-0.66, which provides the maximum optical density of the extract. The latter decreases sharply when exceeding the specified limits. Example. In the extraction funnel, 50-100 ml of a solution containing 0.1-1.0 µg / ml of gold are placed, 2.5 ml of a 10 M solution of dithiopyrylmethane in 3 M sulfuric acid, 5 ml of a 0.1 M solution of sodium perchlorate are added to it, 10 ml of a mixture of chloroform-isobutyl alcohol (1: 0.3) is added and extracted with 1 minute. The optical density of the extract is measured at 369 nm in a 1 cm cuvette. The gold content is calculated on a schedule basis.

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The proposed method for the extraction-photometric determination of gold makes it possible to reliably and accurately determine gold when it contains 1 µg / ml in the analyzed objects from O, without separating the accompanying ones. The proposed method surpasses the known ones in sensitivity, selectivity and, as a result, in the speed of performing analytical operations, especially at low gold contents (Tables 2 and 3). .

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The results of the comparison of the main parameters of various methods for determining gold are presented in Table 2,

As can be seen from the above data, the proposed method surpasses the known and prototype in sensitivity and selectivity, which allows you to determine small quantities of gold with the least error.

The results of the determination of gold in molybdenum concentrates are presented in Table. 3

Table 1

Rhodazole-XS

Used reagent Extrarent

Extraction conditions

Not extracted

Dithioprilamine

A mixture of isobutyl alcohol with chloroform (dichloroethane) The ratio in a mixture of 1: 0,66-0,23

Claims (1)

METHOD FOR DETERMINING GOLD, including its conversion to a colored complex with dithiopyrilmethane in the presence of perchlorates in an acidic medium, solvent extraction and subsequent photometric measurements of the extract, characterized in that, in order to increase the sensitivity and selectivity of the analysis, a mixture of dichloroethane or chloroform with isobutyl is used as a solvent alcohol with a volume ratio of 1: 0.25-0.66.