The Determination of Total Nitrogen Oxides in Stack Gases. Phenoldisulfonic Acid Method

摘要

The well known Saltzman method for oxides of nitrogen is intended for the determination of these constituents in the ambient atmosphere in the range of a few parts per billion to about 5ppm. However, when sulfur dioxide is present in the gas to be sampled and/or the concentration range of the oxides of nitrogen is from five to several thousand ppm, the Saltzman method is not suitable, and the method using phenolsisolfonic acid (PDS) is used as discribed here. This method is good for stack gases but is unsuitable for ambient atmospheric sampling. In the PDS method grab samples are collected in evacuated flasks, absorbed in an acidic medium, and determined colorimetrically.