RU2474809C1 - Method for direct measurement of concentration of mobile mineral forms of phosphorus in soil samples during extraction thereof with carbon-ammonium extractant and apparatus for realising said method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: carbon dioxide released upon mixing a reagent and a soil extract and which hinders spectrophotometry is first removed by evacuation using a specially designed process cassette, which is characterised by the availability of a special holder which enables to hold cups in the chassis of the cassette, and a vacuum lid whose collector is linked by vacuum channels to each separate container. The design of the cassette and the cassette cover enables to pump carbon dioxide from each heat-resistant cup mounted in the socket of the process cassette. Determination is carried out on a spectrophotometer in the spectral range of 898-900 nm of solutions which are coloured to determine phosphorous using a flow cell.

EFFECT: method and design for realisation thereof enable to increase efficiency of analysis and increase accuracy of measuring concentration of mobile mineral forms of phosphorus in soil samples during extraction thereof with a carbon-ammonium extractant.

3 cl, 9 dwg

Description

The scope of the invention relates to chemical methods of soil analysis using in-line technology of analytical work, for example, in assessing the fertility of agricultural land.

The invention, for example, can be effectively used in analytical laboratories when measuring the concentration of mobile mineral forms of phosphorus in soil samples with its extraction with a carbon ammonium extractant.

There is a method of determining the mobile forms of phosphorus and potassium in a carbon ammonium extract from soils with in-line technology of work in a non-automated measurement mode using a KFK-3 colorimeter and a FPA-2 flame photometer (OST 10 256-2000, p. 17). To determine the phosphorus by this method, sample samples are placed in polyethylene containers of the technological cassette, a solution of ammonium carbonate is added to the containers with a multi-position dispenser, the contents of the cassette are agitated and, after 18 hours of exposure, the soil suspension is filtered in polyethylene containers of the receiving technological cassette, and then in a selected aliquot of the carbon ammonium soil extract add the appropriate amount of coloring reagent and after 15 minutes photometrically in the spectral range of 890-900 nm, using non-flowing filling cuvette with a base of at least 20 mm.

In the interaction of an alkaline carbon ammonium extract with an acid staining reagent, gaseous carbon dioxide is released from the solution, which precipitates on the walls of the cell and changes the light absorption of the solution, thereby distorting the results of measuring the concentration of phosphorus in the solution. The specified OST, when this phenomenon occurs, prescribes to pour and re-fill the solution into the cuvette. This phenomenon in a manual mode interferes with the measurement of phosphorus concentration in solution and reduces the productivity of analytical work.

The essence of the invention lies in the fact that after mixing the reagent and soil extract, the evolving carbon dioxide gas is removed by vacuum and spectrophotometry of the solution is carried out using not a flow but a flow cell. To do this, in glass containers 1 (Fig. 1, 2, 3, 4, 6, 7, 9) in the form of heat-resistant glasses located in a specially designed cassette with heat-resistant glasses for evacuating carbon dioxide (Fig. 1 is a general view of the cartridge assembly ; Fig.2 - cartridge with removed heat-resistant glasses; Fig.4 - cartridge with fixed heat-resistant glasses; Fig.3 - individual components of the cartridge), pre-dose the coloring reagent, where then an aliquot of the filtrate taken from the receiving process cartridge with a multi-position dispenser is added Ornik, then the cartridge with heat-resistant glasses is closed with a specially designed vacuum cover 8 to seal the heat-resistant glasses (Fig. 7 - vacuum cassette lid in the technological cassette; Fig. 8 - technological cassette closed with vacuum cassette lid) and the evolved carbon dioxide is pumped out, after which it is determined phosphorus concentration using a flow cell on a spectrophotometer in the spectral range of 898-900 nm.

The removal of carbon dioxide is necessary so that the bubbles of the indicated gas do not overlap the light flux in the measuring cell of the colorimeter and make it possible to work using a flow cell, which simplifies and speeds up the colorimetry.

A cassette with heat-resistant glasses (Figs. 1, 2, 3, 4) for evacuating carbon dioxide during the direct measurement of the concentration of mobile mineral forms of phosphorus in soil samples consists of a metal frame 4 with holes in which heat-resistant glasses 1 can be freely inserted, strips 2 for lifting all glasses at the same time. A feature of the cartridge we offer is that its design has a special holder 3 (Fig. 4), consisting of a bar with fixing clamps 5 (Fig. 5), a lifting guide bar with a handle 6, and stops 7 when lifting the holder when it is extended and provides fixation of the glasses in the cassette frame (Fig.6) when it is turned over to pour the contents of the glasses or wash them.

Vacuum cassette lid 8 for sealing heat-resistant glasses in a process cassette is shown in Fig. 7, and Fig. 8 shows a process cassette closed with a cassette lid. The cover consists of a metal channel 13 (Fig. 9) with holes, a vacuum seal 14, a collector 16 and side locks.

The design of the cover (Fig.9) allows you to reliably seal the capacity of the glass 1 in the cassette 4 for fast pumping of carbon dioxide. The nozzle 11 (Fig. 9) of the vacuum cover connects the inner space of the cup 1 through the vacuum channel 10 to the manifold 16. Vacuum seals 12 seal the threaded connections of the fittings 11 and 15 with the metal channel of the lid 13 and the manifold 16. The metal washer 17 and nut 18 fixes the nozzle 11 through the vacuum seal 14 on the channel 13 of the cover. The tube 9 is connected to a vacuum pump for pumping carbon dioxide.

Due to the fact that the collector is connected by vacuum channels 10 to each individual tank 1, independent pumping of carbon dioxide from each heat-resistant glass is ensured; thereby increasing the pumping speed of carbon dioxide.

The proposed method dramatically increases the productivity and quality of analytical work when measuring the concentration of mobile mineral forms of phosphorus in soil samples after extraction with a carbon ammonium extractant.

Thus, we offer:

1. A method for directly measuring the concentration of mobile mineral forms of phosphorus in soil samples when it is extracted with a carbon ammonium extractant and a device for its implementation in a continuous technology for determining the agrochemical parameters of soils, namely, that sample samples are placed in polyethylene containers of the process cartridge, carbon dioxide solution is added to the containers ammonia with a multi-position dispenser, shake the contents of the cassette and, after an 18-hour exposure, filter the soil suspension into polyethylene containers receiving technological cassette, characterized in that for the further determination of phosphorus in glass containers in the form of heat-resistant glasses located in a specially designed cassette (Fig. 1), a coloring reagent is pre-dosed, to which an aliquot of the filtrate taken from the receiving technological cassette with a multi-position dispenser is then added with a sampler, then the cartridge with heat-resistant glasses is closed with a specially designed vacuum cover 8 (Fig. 7) and the evolved carbon dioxide is pumped out after the concentration of phosphorus using a flow cell for a spectrophotometer in the spectral range 898-900 nm.

2. A cassette with heat-resistant glasses (Fig. 1, 2, 3, 4) for evacuating carbon dioxide when implementing a method for directly measuring the concentration of mobile mineral forms of phosphorus in soil samples after removing it with a carbon ammonium extractant, consisting of a metal frame 4 with holes in which it is possible to freely insert heat-resistant glasses 1, straps 2 for simultaneous lifting of all glasses, characterized in that the design has a special holder 3 (figure 4), consisting of a strap with fixing grips 5 (figure 5), lifting a guiding bar with a handle 6 and stops 7 when lifting the holder, when it extends and secures the glasses in the cassette frame when it is turned over to pour the contents of the glasses or wash them.

3. Vacuum cassette lid 8 (Figs. 7, 8) for implementing a method for directly measuring the concentration of mobile mineral forms of phosphorus in soil samples when removing it with a carbon ammonium extractant, consisting of a metal channel 13 (Fig. 9) with holes, a vacuum seal 14, a collector 16 and side locks, characterized in that the collector is connected by vacuum channels 10 to each individual tank 1, which provides independent pumping of carbon dioxide from each heat-resistant glass, thereby increasing the pumping speed of two carbon monoxide.

Claims (3)

1. A method for directly measuring the concentration of mobile mineral forms of phosphorus in soil samples when it is extracted with a carbon ammonium extractant in a continuous technology for determining the agrochemical parameters of soils, which involves placing sample samples in polyethylene containers of a process cartridge, adding a solution of ammonium carbon dioxide to a container with a multi-position dispenser, and shaking the contents of the cassette and, after an 18-hour exposure, filter the soil suspension into polyethylene containers of the receiving process cassette, from characterized in that for further determination of phosphorus in glass containers in the form of heat-resistant glasses located in a specially designed cassette, a coloring reagent is pre-dosed, to which an aliquot of the filtrate taken from the receiving process cassette with a multi-position dispenser is then added, then the cassette with heat-resistant glasses is specially closed designed vacuum cover and evacuate the carbon dioxide, and then determine the concentration of phosphorus using We use a flow cell on a spectrophotometer in the spectral range 898–900 nm. 2. A cassette with heat-resistant glasses for evacuating carbon dioxide when implementing a method for directly measuring the concentration of mobile mineral forms of phosphorus in soil samples after extraction with a carbon ammonium extractant, consisting of a metal frame with holes in which heat-resistant glasses and slats can be freely inserted, for lifting all glasses at the same time , characterized in that the design has a special holder, consisting of a strap with locking clamps, a lifting guide bar with a handle and limiters when lifting the holder, when it extends and ensures that the glasses are fixed in the cassette frame when it is turned over to pour the contents of the glasses or wash them. 3. Vacuum cassette lid for the implementation of a method for directly measuring the concentration of mobile mineral forms of phosphorus in soil samples when it is extracted with a carbon ammonium extractant, consisting of a metal channel with holes, a vacuum seal, a collector and side locks, characterized in that the collector is connected by vacuum channels to each individual capacity, providing independent pumping of carbon dioxide from each heat-resistant glass.

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