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This specific detector is sensitive to nitrogen (N) or phosphorus (P) compounds. It comprises a small ceramic cylinder doped with an alkaline salt (e.g. rubidium sulfate). A voltage is applied to maintain a small plasma (800°C) through the combustion of an air/hydrogen mixture (Figure 2.12). Compared with FID, the flame is much smaller. Compounds containing nitrogen or phosphorus give, fairly specifically, decomposition fragments transformed into negative ions. These ions are then received by a collector electrode. The nitrogen present in air is inactive. Detector sensitivity is typically 0.1 pg/s for nitrogen‐ or phosphorus‐containing analytes, with a linear range of five orders of magnitude. However, it varies a lot with settings.