Our Research on Improving Silver Content Measurement in Mushrooms Supported by the AV21 Strategy

19. 05. 2025

The scientific team of Iva Synková and Jan Borovička from the Nuclear Physics Institute and the Institute of Geology of the Czech Academy of Sciences has contributed to uncovering an interesting analytical issue in determining the silver content in mushrooms — specifically in the rare Amanita strobiliformis.

This distinctive and relatively rare mushroom is one of the so-called hyperaccumulators — it can concentrate more than a thousand milligrams of silver per kilogram of dry biomass in its fruiting bodies. It typically grows in warmer regions of Europe, mostly on calcareous soils. In the Czech Republic, it is most commonly found in parks and light forests under lime and oak trees. Due to its large size and pale fruiting bodies, it may sometimes be mistaken for parasol mushrooms or other Amanita species.

The study, supported by a grant from the Grant Agency of Charles University and conducted within the AV21 Strategy research programme, shows that although the mushroom contains a substantial amount of silver, not all analytical methods are capable of detecting it properly.

The researchers found that the use of ICP-MS (Inductively Coupled Plasma Mass Spectrometry) — a widely used, highly effective, and accurate analytical method — poses challenges. This method requires converting the powdered mushroom sample into a liquid state, i.e. its decomposition in acid. However, a peculiar phenomenon occurs during this process: the silver present in Amanita strobiliformis reacts almost instantly with naturally occurring chlorine in the sample, forming insoluble silver chloride. This reaction is a serious issue for ICP-MS: up to 98 % of the silver content becomes undetectable, giving the false impression that the mushroom contains almost no silver.

To achieve accurate silver measurements, the researchers used several independent analyses via Instrumental Neutron Activation Analysis (INAA). This method detects elements in the sample without the need for decomposition, and thus avoids the formation of silver chloride. Where INAA is not available, the authors recommend using an unusual two-step decomposition method according to Joerger et al., which enables accurate silver quantification even at high concentrations using ICP-based techniques.

These findings may have broader implications—not only for ecology and environmental chemistry, but also for applied research in biotechnology and remediation of contaminated soils. The study also highlights the importance of choosing appropriate analytical methods and may serve as a valuable teaching example in analytical chemistry.

This project was supported by the Grant Agency of Charles University (project by Iva Synková: Chlorine and bromine content in fruiting bodies of macrofungi – accumulation, phylogenetic and distributional dependencies). INAA measurements were carried out at the Center of Accelerators and Nuclear Analytical Methods (CANAM) infrastructure of the NPI CAS Řež. The employment of the Czech International Centre of Research Reactors (CICRR) infrastructure supported by the Ministry of Education, Youth, and Sports of the Czech Republic (MEYSCR) project LM2023041. The project was closely linked to the activities of the Reactor Centre of the Nuclear Physics Institute of the CAS and is part of the broader AV21 Strategy framework, specifically the programme Fungi – New Threats and Opportunities.

Our Research on Improving Silver Content Measurement in Mushrooms Supported by the AV21 Strategy

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