Figure   21.  The Separation of a PIANO Standard Mixture The sensor was held at 250oC (50oC) above the maximum column temperature to avoid condensation in the jet and conduits. The sample size was 0.1 ml, which was split 100-1, giving a total charge of about 1 mg. Helium was used as the carrier gas at a linear velocity of 20 cm/sec. It is seen that the baseline is extremely stable despite the temperature program, and that the  high sensitivity and wide dynamic range of the FID make it invaluable for quantitative analysis

nbsp; Courtesy of Supelco Inc.   Figure 23. The Separation of a PIANO Standard Mixture   The Nitrogen Phosphorus Detector (NPD) The nitrogen phosphorus detector (NPD), is a highly sensitive but specific detector and evolved directly from the FID. It gives a strong response to organic compounds containing nitrogen and/or phosphorus. Although it appears to function in a very similar manner to the FID, in fact, it operates on an entirely different principle. A diagram of an NP detector is shown in figure 24.   Figure

, the diluting effect has no impact on the sensitivity. The FID detects virtually all carbon containing solutes, with the exception of a small number of small molecular compounds such as carbon disulfide, carbon monoxide, etc. In fact, due to its diverse and comprehensive response, it is considered a universal detector.   An example of the use of the FID in a paraffin, isoparaffin, aromatic, naphthene and olefin analysis of a hydrocarbon mixture (frequently called the PIANO analysis) is shown in figure 23. The column was the Petrocol DH 50.2, 50 m long and 0.5 mm I.D. and made from fused silica. The column temperature was held a 35oC for 5 minutes and then programmed up to 200˚C at 2˚/min. The carrier gas was helium and the mobile phase velocity of 20 cm/sec. Many standard tests carried out in the hydrocarbon and pharmaceutical industries and for environmental testing have been designed to utilize the FID as the detector