Comment on "Worldwide basket survey of multielemental composition of white button mushroom Agaricus bisporus": The credibility of the concentration data reported for REE are questioned - are they reliable enough to be included in the database on nutrients in mushrooms?

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Citation abstract

The focus of this comment is on the Lanthanides (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) which, together with Sc and Y are also called the rare earth elements (REE). Individual REE have similar chemical properties and can be treated as a group. They behave similarly in the environment and in food webs. However, the determination of REE in foods, including edible mushrooms is analytically very challenging. In study by Siwulski et al. (2020) concentrations were reported for Ce, Nd, Sm, La, Sm and Tm, but the others were not detected above the method quantification limit. The sum of Ce (340-2730 μg kg -1 dw), Nd (10-1220 μg kg -1 dw), Sm (10-420 μg kg -1 dw), La (10-130 μg kg -1 dw), Sm (10-420 μg kg -1 dw), Tm (10-170 μg kg -1 dw) in 32 samples of A. bisporus was in the range of 430-3510 μg kg -1 dry weight. The first visible characteristic is a large difference in the concentrations of Ce, Nd, Sm, La and Tm between the A. bisporus samples and various wild species and cultivated Cyclocybe cylindracea and Pleurotus ostreatus. Secondly, there is no correspondence with the Oddo-Harkins order and the concentrations pattern of Ce, Nd, Sm, La and Tm reported for the A. bisporus samples. The pattern is clearly different from that observed in the wild mushrooms and the two cultivated species reported by other studies. The ICP-OES and also the low resolution ICP-MS determination of REE directly from a fungal digest can suffer from spectral interferences of different types including an effect of the matrix which have to be overcome in the course of reliable and controlled analysis of REE.