Determination of the vapours of organic substances and inorganic aerosols in non-corrosive gases by gas chromatography; Quantitative dynamic sorption of vapours through a column of granulated sorbent - Mecklenburg's equation

Abstract

The conditions of quantitative dynamic sorption of organic solvent vapours from inert gases on a column (6 mm diameter) of granulated (1.0-1.2 mm) active charcoal were investigated. The dependence of the time of quantitative sorption on the height of the sorbent column, on physico-chemical properties and the concentration of adsorbate, and on the flow rate of the analyzed gas was followed by recording breakthrough curves. For the evaluation of the efficiency of sorbent columns the equation of dynamic inefficiency of the column was proposed by means of which Mecklenburg's equation was extended to the form enabling the calculation of minimum height of the sorbent bed for the required time of sampling at a given flow rate of the analyzed gas, maximum permissible flow rate of the analyzed gas for the required time of sampling by a column of a given height, and maximum permissible times of the sampling by a column of a given height, for a given flow rate of the analyzed gas. Maximum permissible times of vapour sampling of some organic solvents are calculated for concentrations Cg ⪬ 10-2Cg0, where Cg0 is the concentration corresponding to the saturated vapour pressure, a column 2 cm high (225 mg of active charcoal) for flow rates 50, 250, 500, and 1 000 cm3 min-1 and minimum height of the sorbent column for vapour sampling for the periods of 10, 20, 40 and 60 min for a flow rate of 500 3 min-1. Conditions are given for the determination of the vapours by sampling through a column 2 cm high.