Wood Ash Database

– Wood for Energy -

Analysis and extraction methods


Atomic fluorescence, or AFS, is used to determine mercury content after cold vaporization and arsenic after hybrid generation. Fluorescence spectrometry, similar to ICP-AES, makes use of atomic light emission. In the case of AFS, however, the emission is achieved not by heat but by light of an element-specific wavelength that is absorbed by the atom and subsequently re-emitted. This technique is highly sensitive; measurements for mercury in water solutions reach the level of ng/l.

Gold trap

With the help of a certain supplement to the instrument, the sensitivity can be improved further. After cold vaporization the mercury vapor is collected in a gold trap, so that an amalgam between mercury and gold is formed. When performing the final measurement, the gold trap is heated and the mercury vapor led to the AFS-detector using argon gas. Use of AFS combined with a gold trap is recommended when mercury content is to be determined on or near the natural occurrence levels in surface water, groundwater and seawater.