Laboratory μ-X-ray fluorescence elemental mapping of herbarium specimens for hyperaccumulator studies

Abstract

Background and aims: An innovative approach “Herbarium Ionomics” used a handheld X-ray fluorescence (XRF) device to non-destructively extract quantitative elemental data (i.e., the metallome) from herbarium specimens. This has led to the discovery of numerous hyperaccumulator plants. Once a new hyperaccumulator is identified through XRF screening, the next step is to verify whether this is in fact ‘real’ as there are numerous causes for anomalous measurements caused by artefacts. Methods: Here we report on the use of a scanning μ-XRF for herbarium specimens to answer the question whether the abnormal concentrations of a particular element truly represent hyperaccumulation as well as reveal broad patterns of elemental distribution to provide the first hints at the ecophysiology of the hyperaccumulated element. Results and conclusions: The use of μ-XRF analysis of herbarium specimens can form the starting point for further studies using specimens properly prepared for micro-analytical investigations.