An Ultrasensitive and Element Specific Photoionization Detection System for Environmental Analysis

The problem of trace analysis at the parts per trillion level in environmental samples has been a challenging one for analytical chemists during the past two decades. The presence of substances in very low concentrations in a complex matrix demands the development of both selective and sensitive detectors for their determination by gas chromatography. The photoionization detector (PID) now commercially available is capable of providing the very high sensitivity desired for trace level analysis. Indeed its low volume ionization chamber make it suitable for use with capillary columns. The PID also lends itself to the development of an element selective detector. This could be expected by catalytic conversion of the effluent to H2S, PH3, and NH3. Scrubbers to remove unwanted gases could yield e.g. PH3 only thereby making the detector P selective. Sensitivities at the pg level could be possible. Additional key words: Chemical detection; Ammonia; Phosphorus; Phosphine.