GB/T 15263-94 Determination of total hydrocarbon in ambient air by gas chromatography
The determination of total hydrocarbons in ambient air is a measure of the particulate matter that bares the potential to be harmful to health. In order to determine the hypothesis and verify quantitative levels, the GB/T15263-94 method of gas chromatography allows for the quantification of total hydrocarbons in air samples. Gas chromatography is a method for analysing volatile organic compounds (VOCs) that it finds in the sampling environment. The main purpose of external atmospheric analysis is to monitor the concentrations of total hydrocarbons in the atmosphere, in order to provide data to policy-makers, who can in turn, develop effective plans to control air pollution.
This standard was developed by the General Administration of Quality Supervision, Inspection and Quarantine of the Peoples Republic of China (AQSIQ) in 1994 and is the only analytical method used to quantify the amount of hydrocarbons in samples of ambient air. The process involves passing the air sample over a adsorbent material, typically Tenax®, which is able to absorb the hydrocarbons from the sample and trap them on its surface. The material is then introduced into the injector of the gas chromatography instrument and heated to desorb the trapped hydrocarbons. Once the hydrocarbons have been desorbed, they are separated according to their chemical structure and polarities. The individual compounds are then identified by using the retention times observed. The compounds are then quantified against reference standards.
The sample preparation and Chromatographic set up is important to ensure that the highest accuracy is achieved with the analysis. The instruments used must be capable of measuring the mass fractions of the hydro-carbon species in the sample and those standards used to produce the calibration curves must have the same chemical characteristics of the compounds being measured. The correct Tenax® adsorbent must be used for the sample preparation and must be of the same type and class of that used for the calibration sample preparation.
The quality assurance requirements of this standard stipulate that the gravimetric analysis of the Tenax® should be made before and after sampling, to determine the adsorbed hydrocarbons and ensure accuracy of the measurements. Furthermore, the grid should be inspected to ensure that the packing is appropriate to the application. The sample preparation process must also be checked and verified by a suitable method such as thermal gravitimetric analysis (TGA).
The method has been examined and verified by the AQSIQ and is the only official method used for the determination of total hydrocarbons in air samples in China. It has been found to be effective and accurate in the determination of total hydrocarbons in ambient air. The method has been successfully implemented in areas such as industrial plants and urban and rural areas to assist in determining the pollution levels of these areas and to help develop and plan strategies to control air pollution. The method can also be used in relation to the implementation of emission and dispersion modelling, in order to assess the environment impact of pollutant sources.
