CS242189B1 - The method of stabilizing the content of N-nitrosodimethylamine - Google Patents

Abstract

The solution concerns a method for determining the content of N-nitrosodimethylamine in technical dimethylamine and in dimethylamine salts of herbicide preparations based on femoxyalkanecarboxylic acids and their combinations with other herbicides by the method of capillary gas chromatography with a selective alkaline flame ionization detector. The solution can be used in the chemical industry and in aquaculture.

Description

242189

BACKGROUND OF THE INVENTION The present invention relates to a method for determining the content of N-nitrosodimethylamine in technical dimethylamine and in dimethylamine salts of phenoxy alkane carboxylic acid herbicides and their combination with other herbicides by capillary gas chromatography with a selective alkaline flame ionization detector. .

The prior art method for the determination of N-nitroso-dimethylamine in dimethyl amine herbicides of phenoxyalkanecarboxylic acid is based on a direct sample feed without purification to a gas chromatography column equipped with a warm emission detector, Ross, RD, Morison, J., Rounbehler, DP , Fan, S., Fine, DH, Presented at Divisions of Pesticide Chemistry, 172 d National Marketing of the American Chemical Society, San Francisco, CA, Sept. 1976. In more than one sample, a cleaning process is needed because the gas chromatographic column is heavily contaminated, see Day, EW Jr., West, SD, Koenig, DK, Powers, FL: J. Agric. 1081-1085).

It has now been found that the content of N-nitrosodimethylamine in dimethylamine technical grade and dimethylaminocyanic acid-based dimethyl amine salts can be determined by the method of the invention.

The present invention is based on the fact that it is subjected to a forced distillation by means of a solvent distillation, the distillate is subsequently extracted with an organic solvent, for example chloroform, and the final known volume of the concentrated extract is determined by the selective capillary gas chromatography method of the N-nitrosodimethylamine an alkali flame ionization detector at a temperature in the range of 40 to 70 ° C and comparing the chromatographic image with a solution containing a known amount of N-nitrosodiomethylamine standard.

The assay of the invention is preferably carried out on a capillary column with an immobilized phase of the silicone polymer type.

In addition to the possibility of determining N-nitrosodiomethylamine, further advantages of the invention reside! in that it allows the rapid, reliable and economically advantageous determination of N-nitrosodimethylamine in technical dimethylamine and in herbicidal compositions for the phenyloxyalkanecarboxylic acid base-methylamine salts and their combinations with other herbicides in routine large-scale and 1-sample samples physico-chemical properties.

The invention is illustrated but not limited by the following examples

Determination of N-nitrosodimethylamine content in technical dimethylamine. To 50 g of dimethylamine, ca 10 cm 3 of concentrated sulfuric acid was added in a 250 cm 3 distillation flask, after small portions and under cooling, and the flask contents were distilled through a descending Liebig cooler. 20 cm 3 of distillate were collected. alkaline reaction by the addition of 1 cm @ 3 of sodium hydroxide solution resulting in CNoOH-0.1 mol.l-1 extraction was extracted twice with 20 cm @ 3 of chloroform. The combined organic layers were concentrated to a volume of 2 cm 3 in a 50 cm 3 flask attached to a tube distillation column. The distillation residue was concentrated to a volume of 1 cm 3 with a stream of nitrogen. The solution was fed to the column of a gas chromatograph column. The content of N-nitrosodimethylamine was determined by comparing the peak height in the thickened extrudate of the sample with the peak height of the chromatographic solution with the known amount of Nmitrosodimethylamine standard. Example 2

Determination of N-nitrosodimethylamine content in the dimethylamine salt of 2-methyl-4-chloro-phenoxyacetic acid. To 50 g of the weighed product in a 500 cm 3 distillation flask was added 50 cm 3 of sodium hydroxide solution with a concentration of CNaOH 66 mol.l-1. The mixture was desilated through a descending Liebig cooler. 10 cm @ 3 of concentrated sulfuric acid were carefully added to 40 cm @ 3 of distillate, in small portions and under cooling. The contents of the flask were distilled through a descending Liebig cooler. 20 cm 3 of distillate were collected. The distillate, after adjusting the pH to basic, by the addition of 1 cm @ 3 of sodium hydroxide at a concentration of 0.1 mol.l -1, was extracted twice with 20 cm @ 3 of chloroform. The combined organic layers were concentrated to a volume of 2 cm 3 in a 50 cm 3 vacuum flask attached to a tubular distillation column. The distillation residue was concentrated to a volume of 1 cm 3 with a stream of nitrogen. The solution was fed to a capillary column of a gas chromatograph. The content of N-nitrosodimethylamine was determined as in Example 1. Example 3

Determination of the content of N-nitrosodimethylamine in Anitene I, i.e., a combination of dimethylamine salts of 2-methyl-4-chlorophenoxyacetic acid, 9-hydroxy-9-fluorocarboxylic acid

Claims (2)

SUBJECT Method for determining the content of N-nitrosodimethylamine in technical diroethylamine and dimethylamine salts of herbicidal preparations based on phenoxyalkanecarboxylic acids and their combinations with other capillary gas chromatography herbicides, characterized in that the sample is subjected to forced distillation by aqueous steam distillation, and in In the final known volume of the concentrated extract, the N-nitrosodimethylamine content is determined by capillary gas chromatography using a selective alkaline flame ionization detector at a temperature in the range of 40 to 70 ° C and comparing the chromatographic record of the sample to that of the N-nitrosodimethylamine standard.