EFFECT OF AMMONIA ON THE RESPONSE OF THE NITROGEN PHOSPHORUS DETECTOR(NPD)

The effect of ammonia as a carrier gas and as a make-up gas on the res ponse of the nitrogen phosphorus detector (NPD) was investigated. This study showed that the response of the NPD increased 2.2 to 10. 3 fold for all studied aliphatic amines when 5 % ammonia in nitrogen was use d as a make-up gas. This increase was about 5.3 to 22.8 fold when ammo nia was used as a carrier gas. The response of the NPD for nitro-aroma tic compounds increased 1.8 to 3.1 fold using 5 % ammonia as a make-up gas and 4.2 fold when ammonia was used as a carrier gas. The higher r esponse obtained using ammonia as the carrier gas is related to improv ements in the chromatographic performance (reduced tailing). The respo nse of the NPD to phosphorus compounds was about 1.5 times higher usin g ammonia either as a carrier gas or as a make-up gas compared to nitr ogen. Although the noise of the NPD increased, the signal-to-noise rat ios for both amines and phosphorus compounds improved with the use of ammonia.