Chromatography Automation: System Control and Credibility Improvement Through Microprocessors

Abstract

Automation of gas chromatography provides well-known benefits but also creates problems caused by uncertainty over the integrity of the analytical data due to loss of control of the analysis by the analyst. The successful application of automation requires systems and procedures to monitor and control the automated process in order to improve the credibility of the analytical results. Credibility improvement techniques and subsystems are described for the system composed of Varian Model 8000 AutoSampler, 3700 Gas Chromatograph, and CDS 111 Chromatography Data System. Fault prevention techniques include diagnostic messages, Electro-Sensor Panel (ESP) to monitor GC functions, and parameter read-out. An automatic flame ignition system ignites the flame during unattended operation. Fault detection systems include MUST peak, automatic analysis termination, automatic multiple injection, and calibration. Fault location techniques described include AutoSampler rack and vial print-out, multiple reports, recorder event marks and parameter plotting. Provision for statistical analysis is provided through communication to a computer or programmable calculator. These techniques are a significant step toward the more intelligent instruments and systems which the microprocessor revolution promises.