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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. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

CCQM-K124 was organized by the Inorganic Analysis Working Group (IAWG) of CCQM to assess and document the capabilities of the national metrology institutes (NMIs) or the designated institutes (DIs) to measure the mass fractions of trace elements (As, B, Cd, Ca, Cr, Hg and Mo) and hexavalent chromium (Cr(VI)) in drinking water. The National Metrology Institute of Japan (NMIJ) and the Government Laboratory, Hong Kong SAR (GLHK) acted as the coordinating laboratories. This comparison is divided into two parts. Part A was organized by the NMIJ and the trace elements were the analytes, and Part B was organised by the GLHK and Cr(VI) was the analyte. In Part A, 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 isotope dilution technique with ICP-MS. The results of As, B, Cd, Ca and Cr show good agreement with the exception of 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. In Part B, results were submitted by six NMIs and one DI. The methods applied were direct measurement using 1,5-diphenylcarbazide (DPC) derivatisation UV-visible spectrophotometry, standard addition using ion chromatography-UV-visible spectrophotometry or HPLC—inductively coupled plasma-mass spectrometry (ICP-MS) and isotope dilution technique with ion chromatography—ICP-MS. The results of all participants show good agreement. Accounting for relative expanded uncertainty, comparability of measurement results for each of As, B, Cd, Ca, Cr and Cr(VI) was successfully demonstrated by the participating NMIs or DIs. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

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. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The CCQM-K128 key comparison was organized by the Inorganic Analysis Working Group (IAWG) of CCQM to test the abilities of national metrology institutes in measuring the heavy metals and organo-tin in leather matrix material or other similar organics content materials, and a pilot study CCQM-P163 was conducted in parallel with this key comparison. The National Institute of Metrology (NIM), P. R. China, acted as the coordinating laboratory. This comparison includes two parts: part A is for heavy metals (eight elements include As, Cd, Pb, Co, Cu, Hg, Ni, Sb) in leather powder with concentrations levels (30 ~ 100) mg/kg, and part B is for organo-tin (tributyltin) in leather powder with the concentration range (150~600) nmol/g. There were 10 laboratories registered and 9 laboratories returned the results, and different measurement methods (ID-ICPMS, ICP-MS, ICP-OES) with the microwave digestion were used in Part A; There were 3 laboratories registered and returned the results, and ID-LC-ICPMS, ID-GC-ICPMS and LC-ICPMS were used in Part B. After several rounds results and technical discussion at CCQM IAWG meeting, the KCRV and which associated uncertainty for each component had been confirmed. The comparison is to ensure the comparable and traceable measurement results for heavy metals and organo-tin in leather products among the NMIs and other designated measurement bodies worldwide. The consequence is relatively successful overall, although some problem of mercury and antimony determination had been discussed and summarized in this report. All participants have shown their capabilities and gained experience through this comparison. The results of CCQM-K128 are expected to cover the measurement capability and support the relative CMC claiming in the leather materials and similar high organics content matrix industrial products. KEY WORDS FOR SEARCH Leather, metal, Organo-Tin Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The key comparison CCQM-K108.2014 was organised by the Inorganic Analysis Working Group (IAWG) of CCQM to test the abilities of the national metrology institutes (NMIs) or the designated institutes (DIs) to measure the mass fractions of inorganic arsenic (i-As, sum of the amount of arsenite [As(III)] and arsenate [As(V)]), dimethylarsinic acid (DMAA), and total arsenic (total As) in brown rice flour. This was the follow-up comparison for the CCQM-K108 & CCQM-P147 (Cd, As, inorganic arsenic, and DMAA in brown rice flour). For total As, no strong outliers among the reported values were observed, and the distribution of the results was narrow, within 3% around the median. For i-As and DMAA, the distributions of the results were slightly wider than that for total arsenic, but no strong outliers among the reported values of i-As and DMAA were observed. Two potentially bias sources, an extraction efficiency of As species (the ratio of the sum of i-As and DMAA to total As) and the quality of primary standard of DMAA, were discussed. The extraction efficiency was estimated as the ratio of the sum of i-As and DMAA to total As. In the previous comparison (CCQM-K108 & CCQM-P147), the extraction efficiency was one of the largest bias sources for i-As and DMAA. However, in this study, all the extraction efficiencies estimated from the reported values were close to 100 %. Regarding the quality of the primary standard solutions, no significant difference was observed among the primary standard solution used by the participants. These results suggest the two potential bias sources mentioned above would not have been majors in this study, and then the technical issues in the previous comparison had been overcome. Accounting for relative expanded uncertainty, a comparability of measurement was successfully demonstrated by the participating NMIs and DIs for the measurement of total As at the level of less than 0.7 mg/kg, i-As at the level of less than 0.6 mg/kg, and DMAA at the level of less than 0.1 mg/kg. These are expected that total arsenic and i-As at mass fractions greater than 0.1 mg/kg and DMAA at mass fractions greater than 0.005 mg/kg in rice flour 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. Furthermore, the results of this key comparison can be utilised along with the IAWG core capability approach. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The CCQM-K123 key comparison was organized by the Inorganic Analysis Working Group (IAWG) of CCQM to assess and document the capabilities of the national metrology institutes (NMIs) or the designated institutes (DIs) to measure the mass fractions of sodium, calcium, potassium, magnesium phosphorous and sulfur in biodiesel fuel (BDF). The National Metrology Institute of Japan (NMIJ) and National Institute of Standards and Technology (NIST) acted as the coordinating laboratories. Results were submitted by 11 NMIs and DIs. The participants used different measurement methods, though most of them used inductively coupled plasma-mass spectrometry (ICP-MS), isotope dilution technique with ICP-MS and inductively coupled plasma-optical emission spectrometry (ICP-OES) with microwave acid digestion. The material was quite challenging and a number of questions were raised at the IAWG meeting. Concerning S, the variation in S results between participants, particularly those using IDMS methods was discussed at the IAWG meeting. BAM, NIST and NMIJ reviewed their experimental conditions, results and/or uncertainty calculations for IDMS. According to the additional evaluation and investigation, the variances between the revised results became smaller than the original one, the revised results were overlapping between IDMS measurements of S content at the k=2 level. It is not possible to calculate a KCRV with values being modified after submission. It was concluded that this KC does not support S measurements. Accounting for relative expanded uncertainty, comparability of measurement results for each of Na, Ca, K, Mg and P was successfully demonstrated by the participating NMIs or DIs. It is expected that sodium, calcium, potassium, magnesium and phosphorus at mass fractions greater than approximately 0.1 mg/kg, 0.1 mg/kg, 0.05 mg/kg, 0.05 mg/kg and 0.1 mg/kg respectively in biodiesel fuel and similar matrices (fuels and oils 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. Furthermore, the results of this key comparison can be utilized along with the IAWG core capability approach.

Edible seaweed consumption is a route of exposure to arsenic. However, little attention has been paid to estimate the bioaccessibility and/or bioavailability of arsenosugars in edible seaweed and their possible degradation products during gastrointestinal digestion. This work presents first use of combined inductively coupled plasma mass spectroscopy (ICP-MS) with electrospray ionization tandem mass spectrometry (ESI-MS/MS) with two-dimensional HPLC (size exclusion followed by anion exchange) to compare the qualitative and quantitative arsenosugars speciation of different edible seaweed with that of their bioavailable fraction as obtained using an in vitro gastrointestinal digestion procedure. Optimal extraction conditions for As species from four seaweed namely kombu, wakame, nori and sea lettuce were selected as a compromise between As extraction efficiency and preservation of compound identity. For most investigated samples, the use of ammonium acetate buffer as extractant and 1 h sonication in a water bath followed by HPLC-ICP-MS resulted in 40-61% of the total As to be found in the buffered aqueous extract, of which 86-110% was present as arsenosugars (glycerol sugar, phosphate sugar and sulfonate sugar for wakame and kombu and glycerol sugar and phosphate sugar for nori). The exception was sea lettuce, for which the arsenosugar fraction (glycerol sugar, phosphate sugar) only comprised 44% of the total extracted As. Interestingly, the ratio of arsenobetaine and dimethylarsinic acid to arsenosugars in sea lettuce extracts seemed higher than that for the rest of investigated samples. After in vitro gastrointestinal digestion, approximately 11-16% of the total As in the solid sample was found in the dialyzates with arsenosugars comprising 93-120% and 41% of the dialyzable As fraction for kombu, wakame, nori and sea lettuce, respectively. Moreover, the relative As species distribution in seaweed-buffered extracts and dialyzates was found to be very similar. Collection of specific fractions from the size-exclusion column to be analysed using anion-exchange HPLC-ESI-MS/MS enabled improved chromatographic selectivity, particularly for the less retained arsenosugar (glycerol sugar), facilitating confirmation of the presence of arsenosugars in seaweed extracts and dialyzates. Using this approach, the presence of arsenobetaine in sea lettuce samples was also confirmed.

The CCQM-K108 key comparison was organised by the Inorganic Analysis Working Group (IAWG) of CCQM to test the abilities of national metrology institutes (NMIs) or designated institutes (DIs) to measure the mass fractions of arsenic species, total arsenic and cadmium in brown rice flour. The National Metrology Institute of Japan (NMIJ) acted as the coordinating laboratory. The participants used different measurement methods, though most of them used inductively coupled plasma mass spectrometry (ICP-MS) or isotope-dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) for Cd and ICP-MS for total arsenic. Regarding arsenic speciation, all participants used ICP-MS coupled with liquid chromatography (LC). Accounting for relative expanded uncertainty, comparability of measurement results for each of total arsenic and cadmium was successfully demonstrated by the participating NMIs or DIs for the measurement of the measurand at the level of less than 0.5 mg/kg. Regarding arsenic species (inorganic arsenic and dimethylarsinic acid (DMAA)), there was, however, a measurement problem still to be solved and that part of CCQM-K108 will be repeated. It is expected that arsenic, cadmium and other metals at mass fractions greater than approximately 0.1 mg/kg in rice flour 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. Furthermore, the results of this key comparison can be utilised along with the IAWG core capability approach. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The effect of added organic acids on the calcium availability of vegetables was investigated using the dialysis profiles obtained from an in vitro simulated gastrointestinal digestion with continuous-flow dialysis method. Citric acid was the most effective enhancer followed by tartaric, malic, and ascorbic acids. For amaranth, which has a low calcium availability (5.4%), a significant increase of availability was observed with increasing concentrations of all acids studied. With the continuous-flow dialysis approach, organic acids could be observed to promote the dialyzability even at an elevated intestinal pH. An enhancement effect from added organic acids was not clearly observed for Chinese kale, which itself contains a high amount of available calcium (52.9%).

The key comparison CCQM-K89 was undertaken to demonstrate the capability of participating NMIs and DIs in measuring the contents of incurred trace elements (total arsenic, cadmium and lead) and essential elements (calcium and zinc) at ?g/g (for arsenic, cadmium, lead and zinc) and mg/g (for calcium) levels in a herb matrix sample by various analytical techniques. This key comparison was organized by the Government Laboratory of the Hong Kong Special Administrative Region (GLHK) and agreed at the Inorganic Analysis Working Group Meeting in Hind?s, Sweden in October 2010 as a benchmarking exercise with arsenic (a trace element) and calcium (an essential element) chosen as the 'exemplary' elements. It was also agreed that a pilot study CCQM-P126 would be run in parallel with this key comparison. The key comparison serves to facilitate claims by participants on the Calibration and Measurement Capabilities (CMCs) as listed in Appendix C of the Key Comparison Database (KCDB) under the Mutual Recognition Arrangement of the International Committee for Weights and Measures (CIPM MRA). A total of 20 NMIs/DIs registered for this programme and 18 of them submitted their results. Most of the participants used microwave acid digestion methods for sample dissolution. For the instrumental determination, a variety of techniques like ICP-MS, AAS, INAA, ICP-AES were employed by the participants. For this key comparison, inorganic core capabilities have been demonstrated by concerned participants with respect to methods including ICP-MS (without isotope dilution), ID-ICP-MS, ICP-AES, INAA, AAS and ion chromatography with iteratively matrix-matched calibration on the determination of total arsenic, calcium, cadmium, lead and zinc in a matrix of herb. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The efficiency of a sequential extraction procedure (leaching with water followed by extraction with driselase and sodium dodecylsulfate) was investigated for quantitative As speciation in cut tobacco by HPLC-ICP-MS. The total As concentration and size-exclusion HPLC-ICP-MS profiles obtained for the extracts were used to select optimal extraction conditions as a trade-off between As extraction efficiency and preservation of compound identity. Leaching the cut tobacco (taken from 3R4F Kentucky research reference cigarettes) with water by either sonication in a water bath for 2 h or microwave-assisted extraction (MAE) at 50 W (50 °C) for only 10 min enabled approximately 42% of the total As in the solid to be extracted. Using anion-exchange HPLC with ICP-MS detection, 89% of the total water-soluble As was, for the first time, reported to be present as inorganic As. The instrumental limits of detection (3σ criterion) obtained for arsenite and arsenate by anion-exchange HPLC-ICP-MS were 10 and 50 ng kg−1 As, respectively. Using this hyphenated method, the presence of DMA and MMA as minor As species in the water-soluble fraction could also be detected. Complementary cation-exchange HPLC-ICP-MS analysis of unspiked extracts and extracts spiked with As standards pointed to the presence of arsenate (as a major As species) and DMA and MMA (as a minor As species). Interestingly, recent XANES results revealed that the cut tobacco contained almost exclusively As(V). Successive extractions with driselase and sodium dodecylsulfate (SDS) on the solid residue led to further extraction of approximately 13% and 8%, respectively, of As from the solid cut tobacco. The total As concentration in a homogenate of cut tobacco (from 3R4F Kentucky reference cigarettes) was found to be 318 ± 9 ng g−1 As (precision as SD, n = 3), as determined by microwave acid digestion followed by collision reaction cell ICP-MS (He mode) with standard addition calibration. The developed hyphenated MS methodology was used to study the speciation of As in water-soluble extracts of 3R4F mainstream smoke. These extracts were, for the first time, found to contain arsenite (As(III)), arsenate (As(V)) and an unidentified As-containing species. XANES analysis also reported a mixture of As(V) and As(III) in mainstream cigarette smoke condensate. The reduction of As(V) to As(III) during dynamic cigarette smoke formation can be explained by the overall smoke redox properties associated with the cigarette combustion process.