RU2427833C1 - Method for simultaneous determination of desmedipham and phenmedipham in soil - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method for simultaneous determination of desmedipham and phenmedipham in soil involves preliminary extraction with an organic solvent. Extraction is carried out in acetone at temperature which is 5°C lower than the boiling point of the solvent. The extract is then analysed using a gas chromatography technique. The advantage of the disclosed method of determining desmedipham and phenmedipham lies in simplification of the method by cutting the number of operations and analysis time. Substance is extracted from the soil in a single cycle and the extract undergoes gas chromatographic analysis. According to the disclosed method, total duration of sample preparation is cut down to 60 minutes and duration of gas chromatographic analysis is cut down to 4.5 minutes. The lower detection limit for each substance is 0.2 mg/kg and analysis is cheap and rapid.

EFFECT: simplification of the method by reducing the number of operations and analysis time, and possibility of simultaneous analysis of two pesticides with similar properties.

1 dwg, 2 tbl

Description

The invention relates to the field of analytical chemistry, in particular to gas chromatographic determination of desmedifam and fenmedifam in soil. Currently, pesticide analyzes are carried out using a number of methods [1-5]. These methods have several disadvantages: the need to boil the sample, multi-stage extraction with an organic solvent, a long stage of purification of the extractant.

The aim of the proposed method is to develop a gas chromatographic method for the determination of desmedifam and phenmedifam, the selection of the optimal extractant and the reduction of analysis time.

The goal is achieved as follows. Acetone was used as a selective extractant. To a sample of 10 g of air-dried soil in a 100 ml conical flask, 20 ml of acetone was added and closed with a stopper. Preliminary extraction was carried out at a temperature of 51 ° C, 5 ° C below the boiling point of acetone (56 ° C). The flask was placed in a water bath (t = 51 ° C) and kept for 30 minutes, after which it was stirred on a shaker for 30 minutes (at room temperature). It was centrifuged for 5 min at 5000 rpm, the extract was poured into a clean 50 ml beaker and 2 μl of the solution was introduced into the chromatograph.

Chromatography conditions. Gas chromatograph "Crystallux-4000M" equipped with TID. Column capillary ZB-5 with a length of 30 meters and an inner diameter of 0.32 mm from phenomenex (USA)

t (evaporator) = 220 ° C,

t (columns) = 220 ° C,

t (detector) = 230 ° C.

Discharge of carrier gas through a column (ml / min): 10.

Carrier gas pressure (atm): 0.76.

Detector pressurization (ml / min): 40.

Hydrogen Consumption (ml / min): 12.

Air Consumption (ml / min): 180.

The processing parameter is height.

The absolute retention time of phenmedifam is 3.4 minutes, the window of time is 0.05 minutes; desmedifam - 3.86 minutes, time window - 0.05 minutes.

Analysis time - 4.5 minutes

The completeness of extraction of desmedifam and fenmedifam from the soil is given in table 1 and table 2.

Table 1 The completeness of extracting Desmedisam from the soil. Wednesday Added mg / kg Mg / kg detected The completeness of extraction% The soil 0.2 0,1607 80.35 ± Δ0.82 0.25 0.2013 80.52 ± Δ0.75 0.5 0.4243 84.86 ± Δ0.71 one 0.865 86.5 ± Δ0.72

The drawing shows a chromatogram of the simultaneous extraction of desmedifam and fenmedifam (0.2 mg / kg each) from the soil according to the method described above.

table 2 The completeness of extraction of phenmedifam from the soil. Wednesday Added mg / kg Mg / kg detected The completeness of extraction% The soil 0.2 0.1579 78.95 ± Δ, 0.5 0.25 0.2 80.01 ± Δ0.36 0.5 0.4107 82.13 ± Δ0.4 one 0.5879 85.79 ± Δ0.53

Hygienic standards (MPC in the soil): desmedifam - 0.25 mg / kg, fenmedifam - 0.2 mg / kg. Thus, the gas chromatographic determination of desmedifam and fenmedifam allows you to quantitatively control the content of these substances in the soil at the DC level.

Information sources

1. Blinovsky I.K. Auth. St. RU No. 1295336 A1, IPC G01N 30/04.

2. Stolyarov B.V. "Guide to practical work on gas chromatography." L., Leningrad State University, 1973.

3. Dolgov B.N. Auth. St. RU No. 1821736 A1, IPC G01 30/06.

4. MUK 4.1.1408-03. Determination of residual amounts of desmedifam in soil, root crops and tops of sugar, table and fodder beets by HPLC. - Enter. 06/30/2003. - M.: Federal Scientific Center for Hygiene. Erismana F.F., 2003 .-- 8 p.

5. MUK 3022-84. Systematic gas chromatographic analysis of micro quantities of herbicides of various chemical nature with the combined presence of water, soil and plants in samples. - Enter. 04/27/1984. - M.: Federal Scientific Center for Hygiene. Erisman F.F., 1984. - 18 p.

Claims (1)

A method for the simultaneous determination of desmedifam and fenmedifam in soil, including their preliminary extraction with an organic solvent and subsequent analysis of the extract by gas chromatography, characterized in that the extraction is carried out in acetone at a temperature below the boiling point of the solvent by 5 ° C.