Biochemical Techniques and Instrumentation

2.6.3.6.3. Flame Photometric Detector (FPD)

Flame photometric detector selectively detects phosphorus (P) and sulphur (S) compounds by burning the column effluents and then measuring the flame intensity at 530nm for P and 365nm for S. It has got two flame tips. The gas effluents mix initially with an excess of hydrogen and burns in the first flame tip producing simpler compounds of S and P. These compounds with an excess of hydrogen then burns in the second flame tip, where S compounds produce a blue flame and P compounds produce green flame. The colour intensity of the flame is proportional to the amount of material in the effluent. These flame intensities are measured through appropriate filter in a photomultiplier. The photomultiplier tube output is then fed to a recorder or integrator.