THE PERFORMANCE OF A DUAL ALKALI AEROSOL FLAME IONIZATION DETECTOR FOR GAS-CHROMATOGRAPHY

The described alkali flame ionization detector (AFID) differs from oth er designs by introducing the alkali salt into the detector in the for m of an aerosol. The preheated, desolvated alkali aerosol salt is intr oduced into a dual hydrogen gas flame assembly. This detector shows no evidence of fatigue due to the constant delivery of salt into the det ector, compared to the fixed alkali supply found in other versions, wh ich can be depleted by vaporization and become easily contaminated. Th is AFID design also allows for operation as an FID by implementing a s imple pneumatic procedure. This paper deals with the performance and o ptimization of the detector using a dual alkali salt aerosol flame des ign for organonitrogen and organophosphorus compounds. Detection limit s were 23.5 pgN/sec for alachlor, 185 pgN/sec for dinoseb, and 4.83 pg P/sec to 10.1 pgP/sec for various pesticides studied. Selectivity rati os are tunable to 6.6 x 10(6) gP/gC, 4.0 x 10(4) gN/gC and 2.3 x 10(3) gP/gN by establishing the appropriate detector gas flow rates.