Design and Construction of Low Cost Electronic Digital lntegrator for Gas Chromatography

Abstract

A simple digital integrator for gas chromatography was designed, anddetails on the performance and the electrical circuits of the unit are described.
The voltage output, from gas chromatograph was invertedly amplified by 100times using ptA-741 type operational amplifier, then fed into the eharge-balancing type voltage-frequency converter and the output pUlse train was counted by integrated circuits (SN 7490 N) and displayed by 5 digit Nixie tubes.
As valleysenser type peak detector was also attached to the integrator, the display couldbe read from the memory of the integrals of the former peak, after recognition ofthe next peak elution.
On memorizing integrals bf the former one by hand and by means of push button switch operation, the display could be read from the, counter, as pules train was counted.
The circuit diagrams are shown irt Figs.2, 3, 4, and the linearity evaluation data of the voltagefrequency converter areshown in Table 1.
As for the gas chromatographic analysis, the preeision and reproducibility of the individual measurement were good, as shown in Table 2 andthecost of construction of the unit was about 1/20 that of the commercial one.