Arsenic speciation analysis in food-related and environmental samples

Metallomics approaches based on the combined use of elemental and molecular mass spectrometry for arsenic speciation analysis in phytoremediating plants, marine algae, cut tobacco and cigarette smoke total particulate matter have been developed. Size-exclusion chromatography (SEC)-ICP-MS is proposed to use as a powerful tool for selecting both the appropriate extractant as well as optimum extraction conditions. Comparative SEC-ICP-MS As profiles and total As concentrations in the extracts were used to identify the optimum condition for As speciation studies as a compromise between extraction efficiency and preservation of compound identity. Methodologies have been developed to gain a better grasp of the factors involved in the uptake and distribution of As in the hydroponically grown Arabidopsis thaliana. The effect of the presence of Se on the As and Hg incorporated into the leaves was investigated here for the first time; Se in the growing media was found not to affect As and Hg concentrations in the leaves. Results also revealed the presence of small amounts of As-PC3, As-PC4 and As-PC5 complexes in the leaves, which were characterized by ESI-Orbitrap MS to minimize ambiguity in species identification. The application of an in vitro dialysis method for predicting the As bioaccessibility in selected edible marine algae, was investigated here for the first time. Results showed low As dialyzability (10-20%) and no transformation of As species, primarily arsenosugars, observed following in vitro gastrointestinal digestion. Knowledge of the distribution of arsenic species in cut tobacco, obtained by sequential extraction, provides an insight into the transformation of arsenic species during the combustion process when the cigarette is burnt. The combustion of organic compounds present in tobacco resulted in the change of redox state and As-species distribution in tobacco smoke. Both the hyphenated MS and XANES techniques were used to obtain information about arsenic speciation in smoke condensates. The results showed that the tobacco smoke contained a mixture of As(III) and As(V); As(III) being found as arsenite and, possibly, thio-arsenite by HPLC-ICP-MS. The reduction of As(V) to As(III) during dynamic cigarette smoke formation can be explained by the overall smoke redox properties in accordance with the cigarette combustion process

Final report of the SIM.QM-S7 supplementary comparison : Trace metals in drinking water

SIM.QM-S7 was performed to assess the analytical capabilities of National Metrology Institutes (NMIs) and Designated Institutes (DIs) of SIM members (or other regions) for the accurate determination of trace metals in drinking water. The study was proposed by the coordinating laboratories National Research Council Canada (NRC) and Centro Nacional de Metrologia (CENAM) as an activity of Inorganic Analysis Working Group (IAWG) of Consultative Committee for Amount of Substance – Metrology in Chemistry and Biology (CCQM). Participants included 16 NMIs/DIs from 15 countries. No measurement method was prescribed by the coordinating laboratories. Therefore, NMIs used measurement methods of their choice. However, the majority of NMIs/DIs used ICP-MS. This SIM.QM-S7 Supplementary Comparison provides NMIs/DIs with the needed evidence for CMC claims for trace elements in fresh waters and similar matrices

CCQM-K124 Trace elements and ehromium speciation in drinking water : Part A: Trace elements in drinking water Part B: chromium speciation in drinking water. Final report

CCQM-K124 was an activity of the Inorganic Analysis Working Group (IAWG) and was jointly coordinated by the National Metrology Institute of Japan (NMIJ) and the Government Laboratory, Hong Kong SAR (GLHK). The Part A of CCQM-K124 was organized by NMIJ and trace elements in drinking water were the measurands. The Part A of the key comparison was undertaken for NMIs and DIs to demonstrate their capabilities in measuring part-per-billion level (in μg/kg) or part-per-million level (in mg/kg) of trace elements in drinking water. It should also facilitate the acquisition of claims in Calibration and Measurement Capabilities (CMCs) as listed in Appendix C of Key Comparison Database (KCDB) under the Mutual Recognition Arrangement of the International Committee of Weights and Measures (CIPM MRA). Results were submitted by 14 NMIs and nine DIs. The participants used different measurement methods, though most of them used direct measurement using inductively coupled plasma-optical emission spectrometry (ICP-OES), inductively coupled plasma-mass spectrometry (ICP-MS) and high resolution ICP-MS and isotope dilution technique with ICP-MS. Other methods were graphite furnace atomic absorption spectrophotometry (GFAAS) and flame atomic absorption spectrophotometry (FAAS). The results of B, Ca, Cr, As and Cd show good agreement except some outliers. Concerning Hg, instability was observed when the sample was stored in the light. And some participants observed instability of Mo. Therefore, it was agreed to abandon the Hg and Mo analysis as this sample was not satisfactory for KC. Accounting for relative expanded uncertainty, comparability of measurement results for each of B, Ca, Cr, As and Cd was successfully demonstrated by the participating NMIs or DIs. Furthermore, the results of this key comparison can be utilized along with the IAWG core capability approach. It is expected that arsenic, boron, cadmium, calcium and chromium at mass fractions greater than approximately 0.1 µg/kg, 1 µg/kg, 0.01 µg/kg, 1 mg/kg and 0.1 µg/kg respectively in drinking water and similar matrices (groundwater and river water etc.) can be determined by each participant using the same technique(s) employed for this key comparison to achieve similar uncertainties mentioned in the present report

Final report of the CCQM-K145: toxic and essential elements in bovine liver

Liver plays a major role in metabolism and acts as a source of energy for the body by storing glycogen. With the growing interest and investigation in the biological effects in recent years, it is important and necessary to develop accurate and comparable analytical methods for elements in bio-samples. It has, however, been 10 years since the tissue sample (bovine liver) of CCQM-K49 key comparison. The purpose of CCQM-K145 is to ensure the comparable and traceable measurement results for essential and toxic elements such as P, S, Zn, Mn, Ni, Mo, Sr, Cr, Co, Pb, As and Hg in bovine liver among NMIs and other designated measurement bodies worldwide. The comparison was agreed by IAWG as 6th IAWG Benchmarking Exercise with Zn and Ni as exemplary elements at the meeting in Korea in the early October 2016. The results of CCQM-K145 are expected to cover the measurement capability and support CMCs claiming for inorganic elements in the similar biological tissue materials and food samples. 30 NMIs and DIs registered in CCQM-K145. With respect to the methodology, a variety of techniques such as IDMS, ICP-OES, ICP-MS(non-ID), AAS and NAA were adopted by the participants. For Zn, Ni, Sr, Pb and Hg measurements, most participants chose ID-ICP-MS method, which showed the better performance in terms of consistency and reliability of the measurement results. In aspect of the traceability for the measurement results in CCQM-K145, most participants used their own (in house) CRMs or other NMI's CRMs to guarantee trace to SI unit. Most participants used similar matrix CRMs for quality control or method validation. Base on different statistic way to calculate the reference mass fraction values and associated uncertainties for each measurand, removal of the suspected extreme values, and discussion at the IAWG meetings, the median values are proposed as the KCRV for Zn, Ni, Mn, Mo, Cr, Pb and Hg; the arithmetic mean values are proposed as the KCRV for P, S, Sr, Co and As. In general, the performances of the majority of CCQM-K145 participants are very good, illustrating their measurement capabilities for Zn, Ni, P, S, Mn, Mo, Sr, Cr, As, Co, Pb and Hg in a complex biological tissue matrix. Bovine liver contains many kinds of nutrients and microelements, it can be regarded as a typical representative material of biological tissue and food. In CCQM-K145, the analytes involved alkali metals and transition elements, metalloids / semi-metals and non metals with a range of mass fraction from mg/g to μg/kg. CCQM-K145 also tested the ability of NMIs/DIs to determine elements that were easy to be lost and polluted, and interfered significantly. The chemical pretreatment methods of samples used in the comparison is suitable for general food and biological matrix samples. A variety of measurement methods used in the comparison represent the main instrumental technology for elemental analysis. Therefore, for supporting CMC claim, CCQM-K145 is readily applicable to measurement of more elements in a wide range of biological materials (including liquids and solids) and meat products