Evaluation of a micro-adsorption detector in liquid and gas chromatography

A study was made with the objectives:

1. Evaluation of a micro-adsorption detector for use in liquid chromatography.

2. Evaluation of a micro-adsorption detector for use in gas ch.ranatography.

3. Investigation of the micro-adsorption cell as a tool for screening chromatographic systems, in adsorption studies, and as a micro-calorimeter.

The micro-adsorption detector was found to have sufficient sensitivity to detect nanogram quantities of a component in either a liquid or gaseous carrier, and to have a linear dynamic range of 10²-10³. These qualities, combined with the selectivity of the detector indicate its usefulness in both liquid and gas chromatographic operations. The major limitation to its use is the characteristic adsorption/desorption responsive curve, which requires increased column lengths or resolution over other detectors such as the UV detector. In addition a semi-quantitative correlation between MAD response and chromatographic retention times indicates that the detector has significant potential as a screening tool for separation systems. By means of a calibration apparatus the detector response was characterized in terms of heat flux and temperature differential, and heats of absorption were calculated at concentrations of 10⁻⁴- 10⁻⁶ molar. These compared favorably with those literature values which were available close to these concentrations.