Organic nitrogen is determined using which method?

Organic nitrogen in wastewater is typically determined using the Kjeldahl method. This method involves converting organic nitrogen compounds into ammonia by digesting the sample with sulfuric acid in the presence of a catalyst. The ammonia is then quantified, which provides a measure of the total nitrogen content, including both organic nitrogen and ammonia.

The Kjeldahl method is widely used because it effectively decomposes organic materials and allows for the accurate measurement of nitrogen, which is crucial in assessing the impact of wastewater on receiving waters. This method is particularly well-suited for organic nitrogen determination, as it can detect both organic and ammoniacal nitrogen after the digestion process.

Other methods, while useful in various contexts, do not specifically target the organic nitrogen component in the same way. Gravimetric analysis is primarily used for mass measurements of substances, colorimetric analysis is based on the detection of specific chemical species often using a color change, and ion chromatography is focused on quantifying ions in a solution rather than total nitrogen content. Therefore, the Kjeldahl method stands out as the appropriate choice for determining organic nitrogen in wastewater analysis.