SU879416A1 - Method of humus substance determination - Google Patents

Description

one

The invention relates to analytical chemistry, in particular, to a method for determining the content of hygromagous substances in peat and products from it.

A weight method is known for determining the content of humic substances by preliminarily separating bitumens, easily hydrolyzable and water-soluble substances, by repeated treatment of the remaining 0.1 weight portion and. sodium hydroxide solution when heated, separating the solution with organic substances (in the form of sodium salts) transferred into it, precipitating humic substances from the solution with acid (sulfuric or hydrochloric), followed by separating humic substances, washing them and drying them to constant

weight 1.

The disadvantage of it is the complexity and duration of the determination process (1.5-2 weeks) due to the large number of operations and the duration of the drying process.

The known method for the determination of humic substances by treating the analyte with caustic soda at 50 ° C and filtering the resulting mass, followed by measuring the optical density, o.i, of the filtrate 2 obtained.

The disadvantage of this method is its duration due to the need for repeated treatment with caustic soda solution.

The aim of the invention is to accelerate the method.

10 The goal is achieved by the fact that in carrying out the method for determining humic substances by treating an analyte with an alkaline agent containing caustic soda at 50-60 ° C,

15 filtering the resulting mass, followed by measuring the optical density of the filtrate obtained, as an alkaline agent, is a mixture of sodium hydroxide and sodium pyrophosphate, taken in a volume ratio of 1: 11-1: 15.

The method is carried out as follows.

Preparation of reference solutions.

A portion (5 g) of pine-cotton grass peat is poured with an alkaline solution in a volume ratio of 1: 100. Alkaline solution - a mixture of sodium hydroxide with sodium pyrophosphate in the ratio

1:11. A portion of peat, filled with an alkaline solution, is drawn on a water bath at 50 ° C for 1 hour. Then the whole mass is filtered.

Two equal volumes of the solution are taken from the filtrate; in the same volume, pure humic substances (actual humic acids) are precipitated with sulfuric acid at pH 1.0. Humic acids are separated, washed with water and dried at 60 ° C to constant weight. Pure humic substances by diluting them in various quantities of solvent (a mixture of caustic soda and sodium pyrophosphate) prepare a series of standard solutions with different contents of absolutely dry pure humic substances (actual humic acids) per unit volume. These solutions colorize and record the values of optical density (extinction) for each solution. According to the obtained data (values of optical density and the content of humic acids proper), a graph is drawn.

From the second volume, in which, in addition to humic substances, there are other non-selective substances (organic substances of the humus type), but in which the content of pure humic substances is already known, a second series of standard solutions is prepared by dentic dilution. They are olorimetricated and the values of optical density are plotted on an already plotted graph. In this way.

get two curves of the values of the optical density of pure gum; owl substances from their concentration and optical density values of all hum / owl substances contained in Topt | a) e (with the presence of non-selective substances), and from the concentration of pure humus substances.

Example. Peat for the production of greenhouse nutrient soil of the first year of use on the basis of pine-grass peat.

A portion (5 g) of the soil is poured with an alkaline solution in a volume ratio of 1: 100. The alkaline solution is a mixture of caustic soda with sodium pyrophosphate in a volume ratio of 1:11. A weighed portion is drawn on a water bath for 1 hour. Then the whole mass is filtered and the solution is colorimetrated. According to the obtained value of the optical density according to the calibration curve, constructed from reference solutions, it is determined (; the content of all humic substances and pure humus substances in the soil is divided.

Example 2: Peat for the production of a greenhouse nutrient soil of the second year of use based on pine-cotton grass peat. The course of the analysis, as in example 1.

PRI me R 3. Peat on products is a greenhouse nutrient soil of the third year of use on the basis of: basic-cotton grass peat. The course analysis and, as in example 1.

These experiments are summarized in table. one.

l and c a 1

T a

The results of determining the content of pure humic substances with different content of pure humus substances,% per absolutely dry sample

35.90

: 7 36, 1: 9 37.30: 11

the ratio of sodium hydroxide and sodium pyrophosphate are given in table 2,

Table 2

Note

H € complete extraction of humic substances Same

Filtration is satisfactory.

Content of pure humic substances,% per absolutely dry weight

: 13

37.30: 15 37.32

Claims (2)

: 20 37.30 Formula of the Invention A method for determining humic substances by treating an analyte with an alkaline agent containing caustic soda, at 50-60 1, filtering the resulting mass, followed by measuring the optical density of the resulting filtrate, characterized in that in order to accelerate the method , as an alkaline agent, a mixture of caustic soda with sodium pyrophosphate, taken in a volume ratio of 1: 11-1: 15, is used. Continued table. 2 Note Same i i Requires significant reactor consumption, which is inefficient. Filtration is difficult due to a strong swelling of the sample, which requires more time. Sources of information taken into account during the examination 1. Zhuravleva MM, Rakovsky V.Ye. About humic acids. Proceedings of the Institute of Peat, Academy of Sciences of the Byelorussian SSR,. 2. Minsk, ed. AN Byelorussian SSR, -1953, p. 72-74. 2.Kunin A.M., Novichkova E.A., Volkova L.I. To the question of determining the content of humic acids in peat, Chemistry and chemical technology, works KPI, vol. 1. M., Nedra, 1967, p. 252-256 (PROTOTYPE).