SU450102A1 - Method for quantitative determination of karbofos in food - Google Patents

Description

one

This invention relates to the field of determination of residual dohimicates in food products.

The known method of quantitative determination of karbofos in food products, for example, grapes, grape juice, plum compote, by extracting raw materials with solvents, cleaning the extract on an adsorbent column, eluting karbofos from the adsorbent, followed by gas chromatographic analysis of the extract.

In order to simplify and improve the accuracy of determination of karbofos in food products according to the proposed method, before extraction, the raw materials are mixed with alcohol, and extraction is carried out with n-hexane.

Purification of the extract was carried out on a column of silica gel, and elution with ethyl alcohol. Before purification, the extract is acidified with concentrated hydrochloric acid.

The proposed method is carried out as follows.

Karbofos extracted from a sample of raw materials n-hexane, mixing the raw material before extraction with alcohol. Then, the resulting extract is purified through a layer of silica gel in a column, acidified before concentration with concentrated hydrochloric acid, and karbofos with silica gel with ethyl alcohol is eluted. The eluate is diluted with water and extracted from the resulting solution with n-hexane.

The hexane extract is evaporated, dried with anhydrous Na2SO4 and analyzed on a chromatograph, followed by calculating the carbofos in the sample according to a calibration graph or by comparing the height of the sample peaks and the standard solution of carbofos in hexane.

Example. A sample of raw material, cut into pieces of fruit or components of the compote, is placed in a 2 ml flask, 10 ml of ethyl alcohol is added and extracted on a shaker three times in 10-2 ml of n-hexane for 15 minutes.

The layers are separated in a separatory funnel, and the emulsion is destroyed with a few millimeters of ethyl alcohol.

The combined hexane extract is washed in a separating funnel twice with / about - 100 ml of distilled water, filtered through a funnel with a wad of cotton and anhydrous Na2SO4 layer and cleaned.

Immediately prior to purification, the hexane extract is acidified with 1-2 drops of concentrated hydrochloric acid and some Na2SO4 is added to it.

Purification is carried out on a KSK-2 silica gel column or by whom (fraction 0.25-0.50 mm), a layer height of 7-8 cm, diameter 1.5 cm. The crushed silica gel is pre-washed 2-3 times. 10% salt acid, then 2-3 times with distilled water and dried for 5--6 h with a gradual increase in temperature to 120 ° C.

The column is filled with silica gel, placed in 300 ml of ethyl alcohol, and then washed with 15-20 ml of n-hexane. The extract of profycKaiOT through the column at a speed of 50- 60 drops per minute, washed the flask twice with 5 ml of hexane and also passed through the column. The filtrate is removed, and karbofos is eluted with 30 ml of ethyl alcohol. The eluate is collected in a separatory funnel, to which 100-120 ml of distilled water is added. From this solution, karbofos is extracted in n-hexane twice for 5 minutes, and the first time into hexane, displaced by elution from the column, and the second - into a portion of 10 ml of hexane.

The combined hexane extract nor the eluate is washed with 30-40 ml of distilled water, then filtered through a lump of cotton wool with a layer of anhydrous Na2SO4 into the flask of an apparatus for the distillation of solvents.

Hexane is distilled off in a water bath through a reflux condenser (35x1 5 cm) to a volume of 4-5 ml, the volume of the obtained extract is measured and the content of karbofos is measured on the chromatograph.

The column with silica gel after elution of the sample with ethyl alcohol is washed with 20-30 ml of n-hexane, after which the next sample is purified on it.

Analysis of the final hexane extract is performed on a chromatograph, for example, Color 6A-69 with an electron recombination detector.

The calculation of the carbophos content in the sample is carried out according to a calibration graph or by comparing the height of the sample peaks and the standard solution of carbofos in hexane with a concentration of 1 µg / ml and 0.5 µg / ml. With a weight of 50 g, the sensitivity of determining malathion is 0.01 micron / kg. The extraction of additives from product samples averages 85%, the analysis time is 1.5-2 hours.

Subject invention

Claims (3)

1. A method for quantitative determination of karbofos in food products, such as grapes, grape juice, plum compote, by extracting raw materials with solvents, cleaning the extract on an adsorbent column, eluting karbofos from the adsorbent, followed by gas chromatographic analysis of the extract, characterized in that simplifying and improving the accuracy of determination; before extraction, the raw material is mixed with alcohol, and extraction is carried out with n-hexane. 2. A method according to claim 1, characterized in that the purification is carried out on a column of silica gel, and the elution is performed with ethyl alcohol. 3. Method according to paragraphs. 1 and 2, characterized in that the extract is acidified with concentrated hydrochloric acid before purification.