SU1541502A1 - Method of determining diclorphenoxyacetic acid and metabolits thereof in vegetative materials - Google Patents

Abstract

This invention relates to analytical chemistry, in particular to the determination of 2,4-dichlorophenoxyacetic acid and its metabolites in plant materials. The goal is to improve the accuracy of the method. The sample is pretreated with HCL by heating in a boiling water bath, followed by extraction of the test substances from the sample with a solvent and their chromatographic determination. 4 tab.

Description

This invention relates to analytical chemistry, in particular to methods for determining the pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) and its conversion products in plant materials.

The aim of the invention is to improve the accuracy of the analysis.

PRI me R. A sample of a biomaterial in the amount of 50 g, consisting of leaves and roots of a pre-treated 1 G-2, 4-D plant, is subjected to grinding and transferred to an I l round bottom flask with thin section and 200 ml of 6 N HC1 are added. A reflux condenser is attached to the flask and boiled in a water bath for a certain time.

In tab. Figure 1 shows the degree of increase in 2,4-D, and its conversion products, depending on the conditions of hydrolysis.

After cooling, the hydrolyzate is transferred to a separatory funnel and is extracted three times with 80% methanol. After each extraction, the hydrolyzate is filtered through a filter paper. The completeness of the extraction of 2,4-D and its conversion products is judged by the level of radioactivity of the extract.

In tab. 2 shows the degree of recovery of 2,4-D and its conversion products depending on the extraction conditions.

Optimum results were achieved with a threefold extraction with 80% ethanol or methanol (96-67% of the 14C-2,4-D absorbed by the plant is recovered).

The combined extract is concentrated on a vacuum rotary evaporator to 200 ml, 10 ml of a 40% aqueous solution of phosphoric volmoramic acid are added and filtered again.

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The filtrate is evaporated on a vacuum rotary evaporator until the solvent is completely removed. The concentrate is transferred to a 1 L separatory funnel and extracted with diethyl ether. Extraction is stopped after complete removal of radioactivity. Usually, extraction is sufficient to completely extract all radioactive substances.

The combined ethereal extract, after washing with distilled water (30 ml) to neutral wash water, is dried over anhydrous sodium sulfate (20 g) for 30 minutes with occasional shaking and the solvent is removed on a vacuum rotary evaporator. The last portions of solvent are removed in a 100 ml flask.

The dry residue is dissolved in 2 ml of 80% ethanol and the solution containing 2,4-D metabolites is separated on a glass plate cm (with a thin layer of 0.4 mm) KSK silica gel (three times chromatographic diethyl ether - formic acid 25: 25: 1 G. Then, silica gel is removed from a 1 cm2 plate, respectively, with RЈ 4-OH-2.3-D 0.20-0.22, with Rf 4-OH-2.5- D 0.30-0.33, with Rf 2,4-D and dichlorophenol 0.5-0.7. The removed silica gel samples are quantitatively transferred into conical flasks, 5 ml of 80% methanol are added, and boiled for 2 minutes and filtered through a boom zhny filter. The extraction is repeated Trid. of Joint alcoholic extract was dried over anhydrous sodium sulfate

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(20 g) for 30 minutes with occasional shaking — the solvent is removed on a vacuum rotary evaporator. Then, the 2,4-D gas and its transformation products are separately determined by gas chromatography. The lower limit of detection is 0.02 mg / kg. Increase ratio 70%.

In tab. 3 shows the analysis of plant objects with a known content, 4-D, labeled with a radioisotope

In tab. H shows the content of 2,4-D and products of its transformation in various plant materials for 14 days.)

The known method makes it possible to determine in plant material only unchanged 2,4-D, but not the products of its transformation. Since most of the 2,4-D under natural conditions is converted into other products (Table 4), it is obvious that the proposed method can significantly improve the accuracy of the analysis.

Claims (1)

Invention Formula The method of determining 2,4-dichlorophenoacetic acid and its metabolites in plant materials by extracting the substances to be determined from the sample with a solvent, followed by their chromatographic determination, characterized in that the sample is pretreated with hydrochloric acid heating in a boiling water bath. 1 2 4 6 2 4 6 6 Table 1 72 86 92 92 74 85 97 In five parallel definitions. Table4 Table 2 61 72 78 71 78 82 Table3