DETERMINATION OF CYANOGEN AND CYANOGEN CHLORIDE USING GAS-CHROMATOGRAPHY WITH A FLAME IONIZATION DETECTOR

The response of a flame ionisation detector (FID) to cyanogen ((CN)2) and cyanogen chloride (CNCl) has been studied. The lower limits of detection for (CN)2 and CNCl were 6 .times. 10-12 moles and 2 .times. 10-11 moles respectively. In a comparative study a thermal conductivity detector gave as its lower limit of detection for both (CN)2 and CNCl 4 .times. 10-11 moles. Both detectors showed excellent linearity over the range 0 to 10 micromoles. The ratio of the gradients of the FID calibrations (CN)2/CNCl were found to be approximately two suggesting the response depended on the cyanide group. The response and stability of the FID was investigated as a function of air and hydrogen flow-rates. The response increased with increasing air flow-rate for both (CN)2 and CNCl up to 300 cm3 min-1, thereafter no significant increase was observed. On raising the hydrogen flow from 10 to 25 cm3 min-1 only a slight increase in the sensitivity of the FID towards both (CN)2 and CNCl was observed. At higher flow rates the response for (CN)2 increased markedly whereas at the same flow rates the response for CNCl increased only slightly.