Response Characteristics of the Melpar Flame Photometric Detector

Abstract

The Flame Photometric Detector developed by Brody and Chaney is a flame emission detector utilizing a photomultiplier tube to monitor the chemiluminescent emission above a hydrogen-rich, hydrogen-air flame. By inserting narrow bandwidth filters of the proper wavelength between the detector and photomultiplier, the response is made to be selective for either sulfur or phosphorus (394 mµ for S; 526 mµ for P). It also incorporates a flame ionization probe making a dual detector. A dual headed version employs two photomultipliers, enabling a FID response and selective detection of both sulfur and phosphorus simultaneously. Minimum detectable quantities of sulfur and phosphorus are 200 picograms and 40 picograms, respectively. The FID/FPD response ratios to hydrocarbons range from 1000 to several thousand, depending on the compound and concentration. Data and calculations are presented for determining whether an FPD response is due to hydrocarbons or to sulfur or phosphorus. Since there is some mutual interference of phosphorus and sulfur at their respective wavelengths, data are presented for determining quantities of each contributing to the response when both are present in the sample.