9- Which of the following is a concentration dependent GC detector? A) Flame Ionization B) Nitrogen - Phosphorus C) Flame Photometric D)Photo-Tonization E) Hall Electrolytic Conductivity

The correct answer is E) Hall Electrolytic Conductivity.<br /><br />Hall Electrolytic Conductivity (HEC) is a concentration-dependent gas chromatography (GC) detector. It measures the conductivity of the gas phase, which is directly related to the concentration of ions present in the gas. The detector operates on the principle that the conductivity of a gas is proportional to the concentration of ions present in it. As the concentration of ions increases, the conductivity of the gas also increases. Therefore, HEC detectors are concentration-dependent detectors.