Method for gas chromatography determination of dimethylamine microconcentration in air

FIELD: analytical chemistry, ecology, in particular controlling of environmental air.

SUBSTANCE: claimed method includes aspiration if air sample through chemosorbtive medium, elution of formed dimethylamine salt, eluate closure with alkali, and gas chromatography analysis of gas phase with flame-ionization detection. Dimethylamine salt elution from adsorbent is carried out with 1 cm3 of distillated water; closured with alkali eluate is held in thermostat for 5 min; and as filling in separating chromatography column chromosorb 103, containing 5 % of PEG-20000 and treated with 20 % hexamethyldisilazane solution is used.

EFFECT: method for dimethylamine detection with improved sensibility and accuracy.

 

The invention relates to analytical chemistry, and particularly to gas-chromatographic determination of trace amine in the air, and can be used for sanitary control of the atmospheric air.

Closest to the proposed technical solution is the way gas chromatographic determination of dimethylamine in ambient air, as described in the manual on control of air pollution RD at 52.04-180-89, M., 1991, s-234.

This method is that the sample air volume of 100 DM3aspiritual through the sorption tube ST-212, pre-treated with 15% sulfuric acid solution, then washed formed dimethylamine salt 1 cm3of ammonium chloride with a concentration of 160 g/cm3. Washout is placed in the ampoule, which is established in the sealed container containing 10 g of potassium hydroxide, incubated 10 minutes at room temperature and analyze the gas phase chromatograph with a flame ionization detector, equipped with a separating column containing one of the attachments: No. 1 - Polisorb 30/160 + 5% PEG-6000 + 5% KOH or 2 - acetylene soot + 5% PEG-20000 + 5% STAKE.

However, this method has low sensitivity definition -0,4 mcg in the analyzed volume of solution, and when the volume of air samples 100 DM3the limit of detection in the air composition is employed, 0.004 mg/m 3. Thus, the lower limit of measurement of the concentration of dimethylamine in the air is almost at the level of maximum permissible concentration (MPC) for atmospheric air, equal to 0.005 mg/m3that limits the measurement of lower concentrations.

The sample preparation process associated with the elution of the sorbate solution of ammonium chloride, location of the eluate in a vial for subsequent sealing it with lye, is unjustified and unnecessarily time-consuming, which introduces additional error analysis. In addition, due to improper formation conditions of the analyzed gas phase at room temperature, which may vary within considerable limits, the quantitative composition of the gas phase may change, which also leads to an increase in the error analysis.

The objective of the proposed technical solutions - improving the sensitivity and accuracy of dimethylamine in sanitary control of the atmospheric air.

This problem is solved due to the fact that the sorbate elute 1 cm3distilled water, seal it with lye, thermostatic for 5 min at 60°and as a nozzle in the separation column used processed 20% solution hexamethyldisilazane the chromo-sorbitol 103 containing 5% PEG-20000.

The proposed method is as follows. Samples of the air in the amount of 100 DM 3aspiritual through the sorption tube ST-212 containing film chemical sorbent, elute formed dimethylamine salt 1 cm3of distilled water. The resulting solution was placed in a resealable container with 10 g of potassium hydroxide, thermostatic 5 minutes at 60°and analyze the gas phase chromatograph with a flame ionization detector, equipped with a separating column with chromo-sorbitol 103, treated with 20% solution hexamethyldisilazane and containing 5% PEG-20000. The limit of detection in the sample solution is 0.05 g, and the limit of determination of dimethylamine in an air sample is 0.0005 mg/m3that corresponds to 0.1 MPC for air.

Thus, the proposed method can significantly improve the sensitivity and accuracy of trace amine in the atmospheric air.

The method of gas chromatographic determination of trace amine in the air, including aspiration of the analyzed air through film chemical sorbent, the elution of the resulting salts of dimethylamine, the sealing of the eluate with alkali and chromatographic analysis of the gas phase with a flame ionization detector, characterized in that the elution exercise 1 cm3distilled water, thermostatic sealed the eluate for 5 minutes pri° And as a nozzle in the separation through column chromatography using processed 20%solution hexamethyldisilazane the chromo-sorbitol 103 containing 5% PEG - 20000.



 

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