The sequential elution technique applied to cryptogams: a literature review

AbstractThe use of bryophytes and lichens as biomonitors of atmospheric contamination, particularly contamination by heavy metals, is a well-known and widely applied technique. Determination of the total concentrations in organisms is often used in such studies, but has some disadvantages that may be resolved by using the sequential elution technique (SET). This technique involves successive washing steps that enable quantification of the elements in the different cell compartments (intercellular, extracellular, and intracellular), and finally determination of the remaining fraction, i.e. particulate material. The key step in the SET is the correct extraction of the extracellular fraction, for which a suitable extractant must be used for each different element considered. We have found only seven studies that have focused on selecting suitable extractants, which may be metal cations or chelating agents. Ethylenediaminetetraacetic acid is presented as the most appropriate extracellular extractant for Al, C...