Flame photometric detectors measure the emission characteristics of samples when burned in a hydrogen flame. As elements combust they emit light at particular wavelengths. This light is detected by a photomultiplier tube. By measuring the signal associated with characteristic wavelengths, specific elements can be detected within the sample.  FPD is most often used as a detector following gas chromatographic separations.  It is particularly sensitive to sulfur and phosphorous containing compounds.  FPD has been widely used in environmental analyses including pesticide analysis. While some stand-alone portable and handheld FPD devices exist, most FPDs are associated with benchtop instruments.  The technique is mature.  Instrument range in price from less than $20,000 to more than $100,000 depending on configuration.