The advantage of direct measurement is the ability to evaluate trace levels in the gaseous composition.

Materials being emitted from volcanoes typically carry heavy metals in the trace level.

Groundwater around the country has been found to contain trace levels of perchlorate.

Nearly all Americans tested have trace levels of flame retardants in their body.

They are very sensitive to the presence of oxygen even at trace level.

This L-tryptophan was found to contain trace levels of impure ingredients.

Some other components such as trace levels of aluminium may result from the treatment process (see water purification).

Now it was back to a trace level again.

It is frequently found at trace levels in water pumped from the ground.

"Yes, by measuring trace levels of the contamination we Can direct you toward the surface."