nitrogenfree

Nitrogenfree is a term used in chemistry, nutrition, and related fields to describe materials or fractions that do not contain nitrogen, either because nitrogen has been removed or because the component is defined as nitrogen-free. In many contexts, the term appears in the calculation of the nitrogen-free extract (NFE), a conventional measure in proximate analysis of feeds and foods.

In animal nutrition, NFE denotes the fraction consisting mainly of readily digestible carbohydrates. It is calculated on a dry-matter basis as NFE = 100 − (crude protein + crude fat + crude fiber + ash). Consequently, NFE approximates soluble carbohydrates such as sugars and starches. The method is indirect and can misclassify certain components.

Beyond proximate analysis, "nitrogen-free" may describe labeling or preparation of reagents, solvents, or matrices intended to lack nitrogen-containing impurities, for example in analytical workflows that measure nitrogen or when preparing samples for nitrogen-detection methods. The usage is highly context-specific and not standardized across disciplines.

Important caveat: declaring something as nitrogen-free does not guarantee overall chemical purity; it only specifies absence of nitrogen within the defined analysis or context. The term is best understood in relation to the specific methodology or labeling standard being applied, and it is largely supplemented by explicit measurements (such as total nitrogen content or the nitrogen-free extract value) in precise reporting.