FPD - Flame Photometric Detector

  • Bandpass filter for sulfur or phosphorus (1 filter installed)
  • Use the dual FPD for simultaneous sulfur and phosphorus detection
  • Detects sulfur compounds to 200 ppb, phosphorus compounds down to 10 ppb
  • Use the FPD/FID or Dual FPD/FID for simultaneous hydrocarbon speciation
The Flame Photometric Detector can detect sulfur compounds, such as H2S or SO2, down to about 200 ppb and phosphorus compounds to 10 ppb. While not 100% selective, the FPD is 100,000 times more sensitive to sulfur and phosphorus compounds than hydrocarbons. The phosphorus response is linear, and the sulfur response is exponential (twice the sulfur yields four times the peak area).
The chromatogram to the left shows the FPD sulfur response to 10 ppm H2S.
This chromatogram shows the FPD phosphorus response to 10 ppm malathion.

The FPD is similar in design to the FID, except that the detector body is light-tight and a second flow of hydrogen purges the optical path between the photomultiplier tube (PMT) and the hydrogen-rich flame. A bandpass filter (at 393 nm for sulfur and 525 nm for phosphorus) mounts in front of the PMT, so only that the emissions from sulfur or phosphorus are detected while other wavelengths are rejected.

The dual FPD detector is equipped with two PMTs and filters for the simultaneous detection of sulfur and phosphorus.

Both the single or dual FPD can be equipped with an FID collector electrode and electrometer, which will detect the hydrocarbon peaks at the same time the PMTs are responding to the sulfur and phosphorus compounds. The FID response is not as sensitive as a pure FID because the hydrogen-rich flame is optimized for sulfur and phosphorus detection, rather than hydrocarbon detection. Users can easily optimize the sulfur-phosphorus response versus hydrocarbons response simply by adjusting the hydrogen/air mixture with the included EPC gas controls.

The three chromatograms at left show the FID/Dual FPD combination detector responses to a 50 ppm malathion sample.

The sulfur PMT in the FID/dual FPD combination detector can detect a 5 ppm malathion sample (left), and the phosphorus FPD can detect a 5 ppb malathion sample (right).

FPD detector (includes either S or P filter, specify at time of order)
FPD/FID combination detector
Dual FPD with sulfur and phosphorus filters
Dual FPD with sulfur and phosphorus filters, and FID collector electrode

FPD - Flame Photometric Detector