Use of a Dedicated Computer for Real-Time Control of Gas Chromatographic Measurements

Abstract

Use of a dedicated computer for data acquisition from and control of a series of chromatographic experiments will be described. The purpose of the work is to check out the basic hardware which has been designed for a chromatographic system to obtain highly precise chromatographic data both in terms of retention time measurements and in terms of quantitative peak area determinations. Studies of the adsorption characteristics of a series of porous polymer and porous glass beads have been made. A chromatographic apparatus with precise temperature and flow control has been developed. Simple solid state logic has been developed for computer control of a pneumatically operated gas sampling valve. The output of the flame ionization detector is digitized by means of an integrating digital voltmeter which is interfaced to the computer. Assembly language software is used for peak detection and integration, noise rejection, location of the peak maximum, as well as sample injection. Real-time interaction with the experiment allows the computer to modify the time of or number of sample injections based on the nature of the detector signal. Operation in real-time also provides additional efficiency in data handling by allowing the rejection of baseline and noise data. The data stored in memory can be dumped on punched paper tape for use with a large computer for sophisticated convolution and curve fitting techniques.