STATISTICAL DESIGNS FOR THE OPTIMIZATION OF THE NITROGEN-PHOSPHORUS GAS-CHROMATOGRAPHIC DETECTOR RESPONSE

Statistically designed and evaluated factorial experiments were used to approach optimum operating conditions for the rubidium bead type of nitrogen-phosphorus gas chromatographic detector to detect small quantities of nitrogen compounds in a hydrocarbon matrix, to study the effects of the operating variables. Simplex designs were used to define the optimum set of conditions. The test variables were hydrogen pressure, air pressure, bead heating current. Only two 23 factorial designs and ten simplex vertices were needed to accomplish these purposes. Detector responses for 12 nitrogen and 12 hydrocarbon compounds were compared with both the nitrogen-phosphorus and flame ionization detectors. The average value of the ratio of nitrogen to hydrocarbon response with the nitrogen-sensitive detector was about 1000:1. Chromatography of several fractions from a chemical extractive fractionation of a coal liquefaction product oil demonstrated the discrimation capability of the nitrogen-phosphorus detectort optimum conditions. © 1979, American Chemical Society. All rights reserved.