Quantitative mapping of mercury and selenium in mushroom fruit bodies with laser ablation–inductively coupled plasma-mass spectrometry

Abstract

This work describes the development of a novel method for quantitative mapping of Hg and Se in mushroom fruit body tissues with laser ablation coupled to inductively coupled plasma-mass spectrometry (LA-ICP-MS). Different parameters of the protocol for preparation of the standards used for quantification via external calibration were assessed, e.g., the dissolution temperature of gelatin standards and the addition of chitosan and l-cysteine as additives to the gelatin-based calibration droplets to better match the sample matrix. While chitosan was not suited for this purpose, the presence of l-cysteine considerably improved the figures of merit of the calibration, leading to limits of detection of 0.006 and 0.3 µg g−1 for Hg and Se, respectively, at a pixel size of 20 × 20 µm. Further, an in-house reference material, ideally suited for the validation of the method for application to mushroom samples, was successfully prepared from a paste of Boletus edulis. The newly developed method was used to investigate the distribution of Hg and Se in tissue sections of five porcini mushroom individuals of three different species (Boletus edulis, Boletus aereus, and Boletus pinophilus) and one sample of a parasol mushroom (Macrolepiota procera). For one sample, additional areas were ablated at higher spatial resolution, with a laser spot size down to 5 µm, which allows a detailed investigation of the spatial distribution of Hg and Se in mushrooms. Graphical abstract

Development of polymer films and biological matrices standards for selenium, mercury and endogenous elements quantitative LA-ICP MS imaging in entire rainbow trout fry

“…The value obtained with polymer films was close to the one of our previous study; no other LODs were reported for this element. For 78 Se, LOD of 0.1 µg.g -1 could be obtained with the polymer films with both normalization, which is slightly better than the one reported by Brauer et al with gelatin-cysteine microdroplets standards (0.3 µg.g -1 ) [21]. Additionally, this value is 10 times lower than the one we obtained in our previous study (1 µg.g -1 ) with He as collision gas [12].…”

“…For Hg, LODs were around 0.3 µg.g -1 with MMS, which is much lower than what Debeljak et al obtained with Hgspiked embedding medium standards (4.9 µg.g -1 ) [29] and what Pozebon et al obtained (2.2 µg.g -1 ) [27]. However, low values of 0.04 µg.g -1 and even 0.006 µg.g -1 could be obtained with liver and gelatincysteine standards analysed by ICP MS/MS [22] [21]. To sum up, LODs for all elements were lower using the polymer film standards compared to MMS.…”

“…Very recently, for Hg and Se quantitative LA-ICP MS imaging in mushrooms, Braeuer et al used standards made of gelatin and L-cysteine deposited as droplets onto glass slides [21]. To assess the validity of the calibration, they prepared a reference material with homogenized mushroom.…”

Recent Progress on Fluorescent Probes in Heavy Metal Determinations for Food Safety: A Review

“…Additionally, it can be combined with other technologies for superior detection efficiency. A new method for the efficient monitoring of the spatial distribution of Hg and Se in mushrooms (with a spatial resolution as low as 5 µm) was proposed for the first time, with researchers using laser ablation (LA) and ICP-MS to quantify mercury and selenium in mushroom substrates with detection limits of 0.006 and 0.3 µg•g −1 , respectively [32]. For accomplishing the simultaneous determination of trace selenium and cadmium in rice samples, G. Lan et al [33] first introduced bypass gas to modify graphite furnace electrothermal evaporation (GF-ETV) and ICP-MS.…”

Atomic spectrometry update: review of advances in the analysis of clinical and biological materials, foods and beverages

“…Interestingly, Pb was only found in the first layer of the white and brown rice whereas Pb had penetrated the second layer in the parboiled rice. Braeuer et al 180 investigated the levels of Hg and Se in edible mushrooms in view of the health risks from Hg accumulation or potential health benefits from Se. Porcini mushrooms from three different species ( Boletus edulis , Boletus aereus and Boletus pinophilus ) and one parasol mushroom ( Macrolepiota procera ) were collected and analysed.…”