SU1745773A1 - Method of quality control of cupels in assaying - Google Patents

Abstract

This invention relates to analytical chemistry and can be used in a assay to control the quality of droplets. On the test drops, 22 weights of 20 g of constant-weight lead assay containing 0.10 mg of silver are cuted. The resulting beads are separated from the droplets, the beads are forged and weighed. It has been found that the bead with a mass of about 0.1 mg is not completely absorbed by droplets, the margin of accuracy of determining Z1. Silver losses do not exceed 5%. The lower limit of the quantitative determinations of silver, which can be carried out using these droplets and existing methods of processing beads, is estimated by the ratio CAgmin m x x, where M is the weight — the mass of the analytical weight; t is the average mass of the bloodcake. When using an analytical sample of 100 g, the minimum amount of silver is 1.06 g / t. 1 з п.ф-лы. 2 tab. V yo

Description

The invention relates to analytical chemistry and can be used in a assay assay to control the quality of droplets, establish the detection limit and the lower limit of the quantitative determinations of silver in the assay assay.

There is a method for controlling the quality of droplets, including culling on 100 test drops of 100 mg of silver each. 20 mg of gold and 20 g of lead assay, calculation of the speed of lead plimification (should be 1 g of lead per minute), calculation of the amount of lead absorbed by droplets (should be 95-98%, the rest disappears as lithium fumes), calculation of losses of precious metals when cupelled (for gold, they should not exceed 0.13-0.3%. a

for silver - 1-5%, incl. silver losses through volatilization of 5-10% and through absorption in droplets of 90-95%).

However, the method requires the consumption of chemically pure gold and silver. The choice of controlled parameters in this method is not sufficiently justified, since the speed of cupellation, the amount of lead absorbed by the droplets, the distribution of silver losses through volatilization and absorption are not explicitly associated with the metrological characteristics of the assay analysis. The choice of the mass of noble metals used in the process of quality control of droplets is also insufficiently substantiated, since it does not allow to reveal the nature of the interaction of small corols with material

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vj VI GJ

Peleu, - Insufficient validity of the choice of controlled parameters and the mass of noble metals does not allow an objective assessment of the metrological characteristics of the assay analysis, due to the properties of the droplets and methods of processing the beads when using chemically pure reagents, namely the limit to the uniform; the lower limit of quantification. Ultimately, these disadvantages of the method do not reliably determine the minimum amount of silver when using chemically pure reagents.

Closest to the invention is a method for controlling the quality of the droplets. Gold is not used in the method.

The purpose of the invention is to increase the efficiency of the droplet quality control process by reducing the minimum amount of detectable silver.

The goal is achieved by fitting the test drops of test lead samples containing 0.15-0.05 mg of silver. The quality of the droplets is estimated in aggregate according to parameters that are either directly metrological characteristics of the analysis — the safety factor of accuracy or associated with them: the proportion of droplets absorbed by the droplet during the cupellation process, the loss of silver during cupellation.

The use of a lead assay containing 0.15-0.05 kg of silver makes it possible to establish the lower limit of the quantitative determinations of silver, which is due to the technology of making droplets and the processing methods of the beads (removing the bead from the droplet, forging the beads). The lower limit of the silver content in the used lead sample is due to the fact that using known methods, removing the bead weighing less than 0.05 mg is much more difficult, and forging it, i.e. cleaning of the bead from the slab and the material of the droplet is impossible. The upper limit of the content of silver in the lead sample used is due to the fact that with increasing mass and time of its culling, the accuracy of the results of the quality control of the drops does not increase.

The greatest difficulty is in the cupellation of lead alloys with low contents of precious metals. therefore, the quality of the droplets must be evaluated in relation to these contents.

The use of the proposed monitored parameters allows a reliable assessment of the effect of the quality of the droplets on the metrological characteristics of the assay analysis. The accuracy factor characterizes the reproducibility of cupellation on the droplets used, silver losses characterize on average the properties of the droplets to absorb noble metals, the proportion of droplets absorbed by the droplets, characterizes the heterogeneity of the droplets in terms of their absorptive capacity.

PRI me R 1. Fit eight test batches of constant mass (5-10 g) containing approximately 0.04 mg of silver on test droplets. There are no cases of complete absorption of the bead but the resulting bead is small, so it cannot be processed (removing the bead from the droplet, forging the bead), the safety factor and the loss of silver cannot be estimated. Thus, in this case it is concluded that the quality of the droplets makes it possible to detect the silver content C — 0.8 g / t (with an analytical weight of 50 g), but quantitative determination of these silver contents is impossible. It is necessary to increase the mass of the analytical sample.

PRI mme R 2. Mount on test drops x 22 weights of constant mass (10-30 g) of lead assay containing approximately 0.10 mg of silver. The resulting beads are removed from the drops. the wedges are forged and weighed. Evaluate the safety margin.

The data are summarized in table 1.

Since the bead weighing about 0.1 mg is not completely absorbed by the droplets, z - 1, silver losses do not exceed 5% (20 g of lead assay contains 0.108 mg of silver), it is concluded that the quality of the droplets is satisfactory. Estimate the lower limit of the quantitative determinations of silver, which can be performed using these droplets and the existing methods of processing the beads by the ratio

g, “YuOO bAgmln I - ;,

Mounts

where Mnaveski - the mass of the analytical sample;

m is the average mass of the bead. For example, when using an analytical sample weighing 100 g

CAgmln 0.10b X jj- - 1.06 G / t.

Froze Cupel on test droplets x 23 samples of constant mass assay lead (30-45 g) containing

about 0.16 mg of silver. The resulting beads are removed from the droplets, the beads are forged and weighed. Evaluate the safety margin.

The data are summarized in table. 2

From the data obtained, it follows that the bead is not completely absorbed by the drops, Z 1, the loss of silver does not exceed 5% (3062 mg of silver per sample contains 0.162 mg of silver per sample). Consequently, in this example, a satisfactory quality of droplets was also established, but at the same time the consumption of assay lead and cupel time increased. When estimating the lower limit of quantitative determinations of silver, an overestimated result is obtained.

Using the proposed quality control method & The assay analysis provides, in comparison with the known methods, an increase in the efficiency of monitoring the quality of droplets in the assay analysis by reasonably reducing the minimum amount of silver to be detected, reducing the consumption of precious metals, providing a more reliable estimate of the detection limit and the lower limit of the quantitative determinations of silver.

Claims (2)

1. A method of controlling the quality of droplets in the assay analysis, including culling the mixture of the assay lead with silver, followed by determining the distribution of silver between the products obtained and evaluating the quality of the droplet, characterized in that, in order to increase the efficiency of the process by reducing the minimum amount of silver to be determined, the creation subjected to a mixture of lead assay from 0.05-0.15 mg of silver. 2. A method according to claim 1, characterized in that the quality assessment of a droplet is cumulatively based on the accuracy margin of the determinations according to the following formula: Z- Ob.r / Or, where o, g is the permissible relative standard deviation of the results of the analysis, in terms of the proportion of silver beads absorbed by the droplet and in the relative loss of silver,%; Or - experimentally obtained relative standard deviation of the analysis results,%.  T a b and c a 1 s - 0,0004056 in - 0,0201 in „- T8.96 19.6 z - 1,0 Table 2