This Process Application Note describes the straightforward 24/7 monitoring of the permanganate absorption number (PAN) which is a measure of the caprolactam purity in the correspondent process. Besides other standards, the method meets ISO 8660. Depending on the production process, other analytes can be additionally monitored: NH4OH, NH4NO2, SO32-, alkalinity, moisture, iron, high/low acidity in cyclohexanone (analon), (NH4)2SO3, H3PO4 and other related components.