Optimization of a microcontroller for the simultaneous logging of temperature and reversed-flow inverse gas chromatography measurements

摘要

The utilization of a microcontroller board, optimized for the simultaneous data logging of chromatographic information, the oven temperature, and remote transfer to a personal computer, is investigated, with the goal to extend the capabilities of a gas chromatograph (Shimadzu GC-14A) which does not include a built-in data logging module. An initial comparison of the chromatographic peaks obtained from solute injections, collected both by a dedicated analog-to-digital expansion card and the microcontroller board, demonstrated the latter's ability to perform accurate analog signal digitization. Afterward, the evaporation of three organic liquids (methanol, acetone, and n-pentane) was studied by reversed-flow inverse gas chromatography. From the temperature variation of the experimentally determined rates, the respective thermodynamic functions of enthalpy and entropy changes of acetone and methanol evaporation were determined. The small deviations from the theoretical values indicate the reliability of the proposed methodology. More importantly, it was made apparent that by utilizing automatic data logging instead of the carrier gas flow reversal procedure, the monitoring of rapid physicochemical phenomena was performed with better accuracy, while the duration of the experiments was decreased with the reduced consumption of gas chromatographic consumables.