The characteristics of an alkali flame detector (AFD) are described in relation to use as a portable phosphorus (7723140) detector. Operating principles are reviewed and tabulated data on AFD sensitivity toward a variety of pesticides is included. Different configurations of the AFD are evaluated based on accuracy, stability, sensitivity, and cost. Alternative detectors, including a chemiionization detector (CID) and a flame photometric detector (FPD), also are considered. Hold up, particulates, hydrocarbon removal, sample flow, hydrogen flow control, and electric power are discussed as important factors in the design of a portable phosphorous detection system. The author concludes that the AFD is too heavily dependent on very precise control of hydrogen flow to enable its use as a portable phosphorous detector. The sensitivity of the FPD to sulfur precludes its use in the phosphorus detector system. The CID is recommended for use in conjunction with cesium- bromide as the alkali salt and catalytic conversion of hydrocarbons. Further testing of the FPD is suggested to reduce sulfur interference.
Environmental Science Division, The Bendix Corporation, Baltimore, Maryland