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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).

The CCQM-K78.a comparison was coordinated by the BIPM on behalf of the CCQM Organic Analysis Working Group for NMIs and DIs which provide measurement services in organic analysis under the CIPM MRA. The key comparison forms part of the OAWG 10-year strategic plan of comparisons. CCQM-K78.a underpins the demonstration of capabilities for value assignment of high polarity calibration solutions. The model system selected was amino acids in aqueous solution. Participants were required to assign the mass fractions, expressed in μg/g, of phenylalanine (Phe), leucine (Leu), isoleucine (Ile) and proline (Pro) present in solution in 0.01 N hydrochloric acid. The content and analytical challenges of the selected analytes are representative of those for typical calibration solutions for polar organic analytes in aqueous solution. Participation in CCQM-K78, a benchmarked measurement capability for assigning the mass fraction content of polar organic compounds (pKow > -2) present at a mass fraction range between 50 μg/g and 500 μg/g in an aqueous solution. It also tested capabilities for the quantitative assignment of isomeric polar compounds of similar chromatographic retention time properties. A satisfactory level of agreement of the results was obtained between participants and with gravimetric values for amino acid content. In the cases where the agreement was not satisfactory, the participants were able to identify a technical cause for the inconsistency. The comparison demonstrated the trueness and precision of double IDMS-based methods as a primary measurement procedure for the quantification of polar analytes in aqueous solution when an isotopically labelled version of the analyte is available as the internal standard. It also demonstrated that amino acid quantification using pre- or post-column derivatization with UV or FLD detection can provide results with comparable levels of performance. In this case, where the purity of the primary calibrators had been assigned with a relative standard uncertainty below 0.2%, results consistent with the KCRV within a relative expanded uncertainty in the range 1% - 2% could be realized and levels of 2%-4% were routinely achieved. KEY WORDS FOR SEARCH Amino acid quantification, leucine, isoleucine, proline, phenylalanine, calibration solution, standard solution, IDMS, primary measurement procedure, polar solution, peptide quantification 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).

Solutions of organic analytes of known mass fraction are typically used to calibrate the measurement processes used to determine these compounds in matrix samples. Appropriate value assignments and uncertainty calculations for calibration solutions are critical for accurate measurements. Evidence of successful participation in formal, relevant international comparisons is needed to document measurement capability claims (CMCs) made by national metrology institutes (NMIs) and designated institutes (DIs). To enable NMIs and DIs to update or establish their claims, in 2015 the Organic Analysis Working Group (OAWG) sponsored CCQM-K131 “Low-Polarity Analytes in a Multicomponent Organic Solution: Polycyclic Aromatic Hydrocarbons (PAHs) in Acetonitrile”. Polycyclic aromatic hydrocarbons (PAHs) result from combustion sources and are ubiquitous in environmental samples. The PAH congeners, benz[a]anthracene (BaA), benzo[a]pyrene (BaP), and naphthalene (Nap) were selected as the target analytes for CCQM-K131. These targets span the volatility range of PAHs found in environmental samples and include potentially problematic chromatographic separations. Nineteen NMIs participated in CCQM-K131. The consensus summary mass fractions for the three PAHs are in the range of (5 to 25) μg/g with relative standard deviations of (2.5 to 3.5) %. Successful participation in CCQM-K131 demonstrates the following measurement capabilities in determining mass fraction of organic compounds of moderate to insignificant volatility, molar mass of 100 g/mol up to 500 g/mol, and polarity pKow < −2 in a multicomponent organic solution ranging in mass fraction from 100 ng/g to 100 μg/g: (1) value assignment of primary reference standards (if in-house purity assessment carried out), (2) value assignment of single and/or multi-component organic solutions, and (3) separation and quantification using gas chromatography or liquid chromatography. KEY WORDS FOR SEARCH benz[a]anthracene (BaA), benzo[a]pyrene (BaP), gas chromatography(GC), isotope dilution (ID), liquid chromatography (LC), mass spectrometry (MS), naphthalene (Nap), organic calibration solution, polycyclic aromatic hydrocarbon (PAH) 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).

Within the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantitè de Matiére (CCQM), key comparison CCQM-K141 and associated pilot study CCQM-P178 were coordinated by the National Research Council Canada (NRC). This comparison was a Track A key comparison that formed part of the OAWG 10-year strategic plan. The comparison demonstrated capabilities for measuring high-polarity analytes in a high-fat and high-protein matrix. The measurand chosen as the model system was enrofloxacin and sulfadiazine in bovine tissue. Thirteen National Metrology Institutes or Designated Institutes participated in the CCQM-K141, while two National Metrology Institutes participated in CCQM-P178. The bovine muscle tissue study material was derived from a single live animal that was administered with chemical based pharmaceutical agents prior to processing. Therefore, the study material was naturally incurred, providing a true test of extraction procedures relative to more commonly encountered spiked materials. NRC confirmed excellent homogeneity and stability of the material prior to shipping. Three 10 g bottles of freeze dried powdered muscle tissue were supplied. NRC also provided isotopically labelled solutions of the two measurands, 13C6-sulfadiazine and enrofloxacin-d5 (HI Salt), to those interested in using isotope dilution mass spectrometry (IDMS) methodologies. Procurement and purity assignment with appropriate metrological traceability of native calibrants were the responsibility of individual participants. The study required extraction, clean-up, analytical separation, and selective detection of the analytes. The level of agreement was reasonable given the measurands and matrix were new for most laboratories. The KCRV values and their uncertainties at the 95% confidence level of 57.81 ± 2.57 μg/kg for enrofloxacin and 2285 ± 68 μg/kg for sulfadiazine were calculated using the DSL means. While one participant's value was voluntarily excluded from the KCRV calculations for enrofloxacin, all other participants demonstrated equivalence for both measurands. Significant effort was undertaken post-study to identify the major sources of variability between results. In particular, the various extraction conditions used by participants were investigated thoroughly. While there appeared to be a correlation between highly acidic conditions and higher recovery, this was not definitive and could not be confirmed. The form of standards employed (i.e. free base vs salts) and potential differential solubility between forms was also a suspected source of variability. Biases could also have been introduced with the choice of solvents used for standard preparation, with some solvents better able to minimize adsorption of the analytes to glass surfaces. KEY WORDS FOR SEARCH enrofloxacin, sulfadiazine, bovine tissue, incurred, key comparison 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).

Extraction, chromatographic separation, and quantification of low-concentration organic compounds in complex matrices are core challenges for reference material producers and providers of calibration services. Evidence of successful participation in formal, relevant international comparisons is needed to document measurement capability claims made by national metrology institutes (NMIs) and designated institutes (DIs). To enable NMIs and DIs to update or establish their claims, in 2014 the Organic Analysis Working Group (OAWG) initiated CCQM-K95.1 “Low-Polarity Analytes in a Botanical Matrix: Polycyclic Aromatic Hydrocarbons (PAHs) in Tea”. This was a follow-on comparison from CCQM-K95 which was completed in 2014. The polycyclic aromatic hydrocarbons (PAHs) benz[a]anthracene (BaA) and benzo[a]pyrene (BaP) are considered priority pollutants by U.S. Environmental Protection Agency and are regulated contaminants in food, pose chromatographic separation challenges, and for which exist well-characterized measurement procedures and standard materials. BaA and BaP in a smoked tea were therefore selected as representative target measurands for CCQM-K95.1. Ten NMIs participated in CCQM-K95.1. The consensus summary mass fractions for the two PAHs are in the range of (50 to 70) ng/g with relative standard deviations of (6 to 10) %. Successful participation in CCQM K95.1 demonstrates the following measurement capabilities in determining mass fraction of organic compounds, with molar mass of 100 g/mol to 500 g/mol and having polarity pKow −2, in a botanical matrix ranging in mass fraction from 10 ng/g to 1000 ng/g: (1) value assignment of primary reference standards (if in-house purity assessment carried out), (2) value assignment of single and/or multi-component organic solutions, (3) extraction of analytes of interest from the matrix, (4) cleanup and separation of analytes of interest from interfering matrix or extract components, and (5) separation and quantification using gas chromatography or liquid chromatography. KEY WORDS FOR SEARCH benz[a]anthracene (BaA), benzo[a]pyrene (BaP), gas chromatography(GC), isotope dilution (ID), liquid chromatography (LC), mass spectrometry (MS), polycyclic aromatic hydrocarbon (PAH), yerba mate tea 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 supplementary comparison APMP.QM-S8: determination of mass fraction of benzoic acid, methyl paraben and n-butyl paraben in soy sauce was coordinated by the Health Sciences Authority, Singapore under the auspices of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM). Ten national metrology institutes (NMIs) or designated institutes (DIs) participated in the comparison. All the institutes participated in the comparison for benzoic acid, while six NMIs/DIs participated in the comparison for methyl paraben and n-butyl paraben. The comparison was designed to enable participating institutes to demonstrate their measurement capabilities in the determination of common preservatives in soy sauce, using procedure(s) that required simple sample preparation and selective detection in the mass fraction range of 50 to 1000 mg/kg. The demonstrated capabilities can be extended to include other polar food preservatives (e.g. sorbic acid, propionic acid and other alkyl benzoates) in water, aqueous-based beverages (e.g. fruit juices, tea extracts, sodas, sports drinks, etc) and aqueous-based condiments (e.g. vinegar, fish sauce, etc). Liquid--liquid extraction and/or dilution were applied, followed by instrumental analyses using LC-MS/MS, LC-MS, GC-MS (with or without derivatisation) or HPLC-DAD. Isotope dilution mass spectrometry was used for quantification, except in the case of a participating institute, where external calibration method was used for quantification of all three measurands. The assigned Supplementary Comparison Reference Values (SCRVs) were the medians of ten results for benzoic acid, six results for methyl paraben and six results for n-butyl paraben. Benzoic acid was assigned a SCRV of 154.55 mg/kg with a combined standard uncertainty of 0.94 mg/kg, methyl paraben was assigned a SCRV of 100.95 mg/kg with a combined standard uncertainty of 0.40 mg/kg, and n-butyl paraben was assigned a SCRV of 99.05 mg/kg with a combined standard uncertainty of 1.36 mg/kg. The k-factors for the estimation of the expanded uncertainties of the SCRVs were 2.26, 2.57 and 2.57, respectively. The degree of equivalence (with the SCRV) and its uncertainty were calculated for each result. All the participating institutes (except in one case for benzoic acid) were able to demonstrate or confirm their capabilities in the determination of polar food preservatives in water or aqueous-based beverages/condiments. 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).

A series of overlapping recombinant antigens, 61 to 74 residues in length, representing polymorphic outer membrane protein 90 (POMP90) of Chlamydophila abortus and two recombinant peptides spanning gene fragment p91Bf99 of POMP91B were assessed by immunoblotting to determine the antigen-binding sites of 20 monoclonal antibodies to POMP90, -91A, and -91B. The epitopes were further restricted by scanning 52 overlapping synthetic 12-mer peptides representing the N-terminal part of POMP90, and the 12-mer epitopes were then analyzed by using hexapeptides to the resolution of a single amino acid. Ten epitopes were defined: 1, TSEEFQVKETSSGT; 2, SGAIYTCEGNVCISYAGKDSPL; 3, SLVFHKNCSTAE; 4, AIYADKLTIVSGGPTLFS; 5, SPKGGAISIKDS; 6, ITFDGNKIIKTS; 7, LRAKDGFGIFFY; 7a, DGFGIF; 7b, GIFFYD; 8, IFFYDPITGGGS; 8a, FFYDPIT; 9, GKIVFSGE; and 10, DLGTTL. The 20-mer peptide LRAKDGFGIFFYDPITGGGS was a major epitope that was recognized by seven antibodies. Epitopes 7 to 10 were conserved in reference strains of the former species C. psittaci , whereas the strong antigenic peptides FYDPIT and IVFSGE were conserved among members of the genus Chlamydophila . Epitopes 3 to 8 were located within the best-scoring beta-helical wrap (residues 148 to 293) predicted for POMP91B by the program BETAWRAP. Other studies have suggested an association of the POMPs with type V secretory autotransporter proteins. The results presented in this study provide some evidence for a passenger domain that is folded as a beta-helix pyramid with compact antigenic organization.

Four major clusters, designated A, B, C and D, were distinguished in Western Blots by a monoclonal antibody specific for the "antigen family at 90 kDa" after two-dimensional electrophoretic analysis on immobilized pH gradient of chlamydial elementary bodies of abortifacient C. psittaci. Clusters B, C, and D were closely related with molecular mass (kDa) pI values of 91.5/5.2-5.4, 90/5.0-5.2 and 90.5/5.6-5.8, respectively. Cluster A was larger, with molecular mass/pI of 104.7/5.1-5.3. Evidence for the antigenic relationship between cluster A and clusters B, C and D was further supported by immunological cross-reaction with affinity-purified antibodies from serum of ewes with chlamydial-induced abortion. The experimental values obtained for size and pI of the four clusters correlated well with the calculated values from known sequences coded by multiple chlamydial genes. Direct evidence for the correspondence between the immunoreactive clusters B, C and D and the retrieved genes was provided by antibody binding experiments to recombinant polypeptides representing fragments of the deduced proteins. The 4-member antigen family at 90/104 kDa is the first example of proteins coded by multiple genes within the genus Chlamydia.