Wiktionary
n. 1 (context chemistry English) A chemical element present in a sample in very small quantities. 2 (context biochemistry English) A chemical element in an organism’s diet that is required in very small amounts in order to maintain proper biochemical function; a micronutrient.
WordNet
n. an element that occurs at very small quantities in the body but is nonetheless important for many biological processes
Wikipedia
A trace element is a chemical element whose concentration (or other measure of amount) is very low ( a "trace amount"). The exact definition depends on the field of science:
- In analytical chemistry, a trace element is one whose average concentration of less than 100 parts per million (ppm) measured in atomic count or less than 100 micrograms per gram.
- In biochemistry, a trace element is a dietary element that is needed in very minute quantities for the proper growth, development, and physiology of the organism. For example, magnesium is a trace metal.
- In geochemistry, a trace element is one whose concentration is less than 1000 ppm or 0.1 % of a rock's composition. The term is used mainly in igneous petrology. Trace elements will be either compatible with a liquid or solid phase. If compatible with a mineral, it will be incorporated into a solid phase (e.g., nickel's compatibility with olivine). If it is incompatible with any existing mineral phase it will remain in the liquid magma phase. The measurement of this ratio is known as the partition coefficient. Trace elements can be substituted for network-forming ions in mineral structures. Trace elements that are not essential to a mineral's defined composition will not appear in the chemical formula of that mineral.
Usage examples of "trace element".
I ordered a Scotch and was given a drink that rigorous chemical analysis might have found to contain a trace element of whisky.
Though Ling had been thoroughly searched, and all possessions seized, she might carry in her body some detectable trace element-acquired growing up on a far Galactic world.
They was on the track of some rare trace element, whatever that is, that was valuable to the Company in runnin' its portable gear and which didn't seem all that common among the worlds, and they was like them dudes who go out searchin' for oil, diggin' here, then there, till they hit a gusher.
But it needed something, some trace element or some such that was present only in the Warden system.
It was the princethe trace element that made them hard and flexible.
It was the prince-the trace element that made them hard and flexible.