Abstract
The effects of loading, desorption volume, and presence of other compounds on desorption efficiency of organic analytes from activated charcoal were investigated. The effects of loading were evaluated by shaking solutions of cellosolve-acetate (111159) (CA) in carbon-disulfide (CS2) with activated carbon and determining the ratio of CA present after equilibration to that before adding carbon. Analysis was by gas chromatography with flame ionization detection. CA desorption efficiency increased nonlinearly with CA loading. The effect of desorption volume was assessed by shaking solutions containing constant loadings of biphenyl (92524) in CS2 with activated carbon. After equilibration, the composition of 0.5, 1, 2, and 5 milliliter volumes of solution was determined. Desorption efficiency was a nonlinear function of desorption solution volume. The desorption efficiencies of solutions containing polar and nonpolar compounds such as toluene (108883), butanol (71363), CA, cumene (98828), and butyl-cellosolve (111762) in a two component desorption solution of 5 percent methanol in methylene-chloride were determined. Desorption efficiency of the solutions was not affected by the presence of polar or nonpolar compounds. The dependency of desorption efficiency on loading, desorption solution volume, and presence of other compounds was discussed. A linear equation expressing desorption efficiency as a function of desorption volume was derived which fit the data for CA well. The author notes that using two component solvent systems for desorption eliminates the dependency of desorption efficiency on the presence of other compounds for mixtures of polar compounds, and that in a mixture of two or more nonpolar compounds there is usually no effect from the presence of one compound on the desorption of others.
