In analytical chemistry
, a trace element
is an element
in a sample that has an average concentration
of less than 100 parts per million
atoms, or less than 100 micrograms per gram.
In biochemistry, a trace element is a chemical element that is needed in minute quantities for the proper growth, development, and physiology of the organism. In biochemistry, a trace element is also referred to as a micronutrient.
In geochemistry, a trace element is a chemical element whose concentration is less than 1000 ppm or 0.1% of a rock's composition.
The term is used mainly in igneous petrology.