The demonstration of competency and equivalence for the assessment of levels of contaminants and nutrients in primary foodstuffs is a priority within the 10-year strategy for the CCQM Organic Analysis WG series of Track A core comparisons. The area of low polarity analytes in high fat foods had not been covered by the OAWG for many years since the key comparison CCQM-K21 p,p'-DDT in fish oil occurring in 2000. Benzo[a]pyrene (BaP) is one of the markers for the occurrence of PAHs in foods, for which maximum residue limits are enforced in many countries. Edible oil and fats are the main source of human PAH intake. BaP may form in edible oils by pyrolytic processes, such as incomplete combustion of organic substances. Worldwide regulatory limits of BaP in edible fats and oils are from 2.0 μg/kg to 10 μg/kg. Comparable and traceable measurement results for BaP in oil are important worldwide. Thus BaP in edible oil was the model system selected to align within the OAWG strategy. 16 NMIs and DIs participated in CCQM-K146. Different methods such as liquid-liquid extraction, GPC and SPE were applied in the sample pre-treatment and HPLC-FLD, HPLC-MS/MS, and GC-MS or GC-MS/MS were applied for detection by the participants. Most participants either used their own CRMs, other NMI's CRMs or pure materials assessed in house to guarantee traceability to SI for the calibrants. One lab was excluded from the KCRV evaluation, as they did not meet the CIPM metrological traceability requirements for their calibrant. Regarding the data evaluation, five labs withdrew their results from the statistical evaluation of the KCRV for technical reasons. In line with the OAWG guidance document for KCRV estimator selection, the Hierarchical Bayes option was selected for the KCRV value, which was determined as 2.74 μg/kg with a standard uncertainty of 0.03 μg/kg. The remaining ten institutes that were included in the calculation of the consensus KCRV all agreed within their standard uncertainties. In general, the majority of CCQM-K146 participants performed very well. Therefore, this Track A Key Comparison directly illustrates the capabilities in determining mass fraction of organic compounds, with molecular mass of 100 g/mol to 500 g/mol, having low polarity pKow < -2, in mass fraction range from 0.1 μg/kg to 1000 μg/kg in a high fat, low protein, low carbohydrate food matrix. 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 gas chromatography-isotope dilution mass spectrometry (GC-IDMS) technique was developed for the quantification of two heavy polyaromatic hydrocarbons (PAHs), benz[a]anthracene and benzo[a]pyrene, in yerba maté tea (maté). The optimisation of two extraction methods, namely liquid-liquid extraction and accelerated solvent extraction, was carried out. Both optimised methods were validated using a certified reference material of fine dust and the results were within the expanded uncertainties at 95% confidence level. Recoveries of 99.2-106.7% with RSD of measurements of 1.1-2.3% were achieved for benz[a]anthracene. Recoveries of 95.7-101.9% with RSD of measurements of 0.4-1.4% were achieved for benzo[a]pyrene. The validated methods were applied for the extraction of benz[a]anthracene and benzo[a]pyrene in maté powder from NIST. A metrological approach was undertaken to ensure the traceability of measurement results. The uncertainties associated with the results were rigorously evaluated and also reported herein. Graphical abstract Quantification of benz[a]anthracene and benzo[a]pyrene using IDMS.

A case study of ordinal data from human organoleptic examination (sensory analysis) of drinking water obtained in an interlaboratory comparison of 49 ecological laboratories is described. The recently developed two-way ordinal analysis of variation (ORDANOVA) is applied for the first time for the treatment of responses on the intensity of chlorine and sulfurous odor of water at 20 and 60 °C, which is classified into the six categories from ‘imperceptible’ to ‘very strong’. The one-way ORDANOVA is used for the analysis of the ‘salty taste’ intensity of the water. A decomposition of the total variation of the ordinal data and simulation of the multinomial distribution of the data-relative frequencies in different categories allowed the determination of the statistical significance of the difference between laboratories in classifying chlorine or sulfurous odor intensity by categories, while the effect of temperature was not significant. No statistical difference was found between laboratories on salty taste intensity. The capabilities of experts to identify different categories of the intensity of the odor and taste are also evaluated. A comparison of the results obtained with ORDANOVA and ANOVA showed that ORDANOVA is a more useful and reliable tool for understanding categorical data such as the intensity of drinking water odor and taste.

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).

The newly developed statistical technique of two-way ordinal analysis of variation (ORDANOVA) was applied for the first time to sensory responses in combination with multinomial ordered logistic regression of a response category vs. chemical composition. A corresponding tutorial is provided. As a case study, samples of a sausage from different producers, purchased at the same time from a market, were compared based on sensory responses of experienced experts. A decomposition of total variation of the ordinal data and simulation of the multinomial distribution of the relative frequencies of the responses in different categories showed a statistically significant difference between the producers’ samples, and an insignificant difference between the experts’ responses related to the same sample. The capabilities of experts were also evaluated. The influence of chemical composition of a sausage sample on the probability of a response category was modeled using multinomial ordered logistic regression of the response on mass fractions of the main sausage components. This statistical technique can be helpful for understanding sources of variation of sensory responses on food quality properties. It is also promising for a revision of specification limits for chemical composition, as well as for the prediction of sensory properties when the chemical composition of the product is subject to quality control.

No abstract

No abstract

No abstract