CS217592B1 - Method of copper regeneration in elemental analysis of substances - Google Patents

Abstract

Copper regeneration plays the role of a reducing charge, for example in the determination of carbon, nitrogen and hydrogen. The essence of the method is that copper oxides formed by copper oxidation are reduced during the analysis by carbon monoxide formed by the reaction of oxygen on a carbon contact. The method is intended primarily for the application of automated instrumentation in organic elemental analysis.

Description

The invention relates to a process for the recovery of copper, which fulfills the role of reducing charge in elemental analysis of substances, for example in the determination of carbon, nitrogen and hydrogen.

In recent years, there has been an increasingly widespread application of automated instrumentation in organic elemental analysis, particularly in the determination of carbon, hydrogen and nitrogen, possibly sulfur, or nitrogen in biological materials. All of these methods are based on the oxidative conversion of a sample into defined reaction products in an internal gas stream, such as helium, and usually with the addition of oxygen only at the time of combustion. After separation of the defined reaction products, the individual products are determined gravimetrically, volumetrically or by means of a thermally conductive detector. Thus, the methods utilize a Pregl-Dumas combustion system which is comprised of an oxidation charge generally represented by combustion catalysts, ie, copper oxide, cobalt-cobalt, chromium, tin, and the like, and reducing charges generally represented by wire or granulated copper. The reducing charge captures unreacted oxygen at 500 to 650 ° C and reduces nitrogen oxides to nitrogen, whereby copper is oxidized to copper oxide. The reduction charge needs to be replaced quite often as it oxidizes rapidly, especially if a large excess of oxygen is used in combustion. In addition, there is a partial uptake of nitrogen oxides on copper oxide, especially in the presence of halogens, thereby distorting the results.

These present disadvantages are overcome by the present method of copper regeneration in the elemental analysis of substances, which is based on the fact that the copper oxides produced by the oxidation of copper are reduced during the analysis by carbon monoxide produced by the reaction of oxygen at the coal contact.

The advantage of the described method over the used ones is that it eliminates the necessity of frequent replacement of the reduction reactor packing and creating optimal and defined reaction conditions for each determination, and thus increasing its accuracy.

Example

Apparatus according to esl. No. 157 857 can be used to determine nitrogen in biological materials. Since a larger amount of sample is burned, a considerable amount of oxygen, for example 50 ml, is added to burn the sample, the excess of which is necessary for complete combustion rapidly depletes the reducing charge. If the same or a smaller amount of oxygen is metered through a coal contact heated to 900 to 100 ° C and the carbon monoxide formed by the reaction is fed to the inlet of the reducing charge, the copper oxides to copper are reduced. Under these circumstances, each determination is carried out on freshly reduced copper and there are no potential complications, for example the uptake of nitrogen oxides on copper oxide.

Claims (1)

SUBJECT Method for the recovery of copper in elemental analysis of substances, characterized in that the copper oxides produced by the oxidation of copper are reduced in the course of the analysis of the carbon monoxide produced by the reaction of oxygen at the coal contact.