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With recently legislated maximum levels of inorganic arsenic (iAs) in white and brown rice in Canada, the regulatory bodies are evaluating the need for regulation of As levels in infant food products. Rice is a major part of infants' diet, and therefore, the presence of As in this staple food causes concerns. So far, the scientific community was lacking suitable certified reference material (CRM) which could be used to assess the accuracy of developed analytical methods for As speciation in infants' food products. As a result, we have developed BARI-1, a baby cereal coarse rice flour reference material which was certified for total arsenic (0.248 ± 0.018 mg kg -1 ), cadmium (0.0134 ± 0.0014 mg kg -1 ), mercury (0.0026 ± 0.0003 mg kg -1 ), lead (0.0064 ± 0.0016 mg kg -1 ), inorganic As (0.113 ± 0.016 mg kg -1 ) and dimethylarsinic acid (DMA) (0.115 ± 0.010 mg kg -1 ), and reference value for monomethylarsonic acid (MMA) (0.0045 ± 0.0008 mg kg -1 ) was reported. We also observed trace amounts of an unknown As compound, with chromatographic retention time close to DMA. Participating laboratories were allowed to use their in-house-validated extraction and/or digestion methods, and the detection of total metals was done by ICP-MS whereas HPLC-ICP-MS was used for As speciation. Despite the diversity in sample preparation and quantitation methods, reported values were in good agreement. For iAs measurement, the comparison between hydride generation ICP-MS and HPLC-ICP-MS found iAs overestimation with the former method, possibly due to interference from DMA. The certification was accomplished with a CRM rapid response approach in collaborative, focused effort completing the CRM development in few months instead of the typical multiyear project. This approach allowed to respond to measurement needs in a timely fashion. Graphical abstract.

The fungi Aureobasidium pullulans, Mortierella humilis, Trichoderma harzianum and Phoma glomerata were used to investigate the formation of selenium- and tellurium-containing nanoparticles during growth on selenium- and tellurium-containing media. Most organisms were able to grow on both selenium- and tellurium-containing media at concentrations of 1 mM resulting in extensive precipitation of elemental selenium and tellurium on fungal surfaces as observed by the red and black colour changes. Red or black deposits were confirmed as elemental selenium and tellurium, respectively. Selenium oxide and tellurium oxide were also found after growth of Trichoderma harzianum with 1 mM selenite and tellurite as well as the formation of elemental selenium and tellurium. The hyphal matrix provided nucleation sites for metalloid deposition with extracellular protein and extracellular polymeric substances localizing the resultant Se or Te nanoparticles. These findings are relevant to remedial treatments for selenium and tellurium and to novel approaches for selenium and tellurium biorecovery.

A new determination method was developed for the measurement of methylmercury (Me-Hg) and inorganic mercury (i-Hg) in biological samples using high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) following alkaline extraction. Mercury species in biological samples were extracted with 10% (w/w) tetramethylammonium hydroxide (TMAH) solution at 80°C for 2 h. Methylmercury was completely separated from i-Hg by adamantyl type and octadecylsilyl type columns within 6 and 4 min using isocratic elution, respectively. The detection limits (3σ) of adamantyl and octadecylsilyl columns using the proposed system were 0.08 and 0.13 ng g -1 (as Hg), respectively. Inorganic Hg completely separates from Me-Hg without tailing. The proposed determination methods were applied to several biological certified reference materials (CRMs). The measurement results of Me-Hg obtained by the present method were in good agreement within the expanded uncertainties (k = 2) with the certified values. The analytical precision (n = 3) of Me-Hg was less than 2%, and the recoveries of Me-Hg and i-Hg were 101 ± 1 and 103 ± 3%, respectively. In addition, this method enables the determination of Me-Hg and i-Hg for 20 samples in 1 h.

A commercial arsenic field kit designed to measure inorganic arsenic (iAs) in water was modified into a field deployable method (FDM) to measure iAs in rice. While the method has been validated to give precise and accurate results in the laboratory, its on-site field performance has not been evaluated. This study was designed to test the method on-site in Malawi in order to evaluate its accuracy and precision in determination of iAs on-site by comparing with a validated reference method and giving original data on inorganic arsenic in Malawian rice and rice-based products. The method was validated by using the established laboratory-based HPLC-ICPMS. Statistical tests indicated there were no significant differences between on-site and laboratory iAs measurements determined using the FDM (p = 0.263, ά = 0.05) and between on-site measurements and measurements determined using HPLC-ICP-MS (p = 0.299, ά = 0.05). This method allows quick (within 1 h) and efficient screening of rice containing iAs concentrations on-site., (Copyright © 2018 Elsevier Ltd. All rights reserved.)