International Activities in Metrology in Chemistry

In today's economy goods and information are being exchanged globally, international travel is commonplace as is the cross-boarder transport of livestock and agricultural products, and this trend is set to continue. Just as important are issues that impinge on our quality of life, such as health care, the environment and food quality. A strong international measurement and standards infrastructure is critical to assure equity in trade and a high quality of life, by ensuring that products and services meet their specifications. In the field of chemical measurements, certified reference materials (CRMs), measurement standards and reference measurement results provide stated references upon which analytical laboratories can anchor their measurement results. The traceability of measurement results to internationally accepted stated references, together with their stated measurement uncertainties, as described in ISO/IEC 17025, provides the basis for their comparability and global acceptance. Recent global activities which are succeeding in developing a system for the international acceptance of chemical measurements are described, notably: activities of the National Metrology Institutes and the BIPM; the Mutual Recognition Arrangement of the International Committee of Weights and Measures (CIPM MRA) for National Calibration Certificates and Measurement Capabilities; the Inter-Laboratory Comparisons organised through the working groups of the Consultative Committee for Amount of Substance – Metrology in Chemistry (CCQM), and the activities of the Joint Committee for Traceability in Laboratory Medicine (JCTLM)

Endonasal resection of a sinonasal hemangiopericytoma

AimHemangiopericytomas (HP) are rare perivascular neoplasms with variable biological behaviour. The prognosis, by histology alone, is difficult. The clinical course of disease and the localization of the tumour are of importance. Sinonasal HP is usually of low malignant potential. Currently, a less invasive, endonasal, approach is chosen for resection of such tumours. One case of sinonasal HP treated by endonasal surgery is presented.CaseA 61-year old man presented with nasal obstruction and stated that he had undergone endonasal surgery elsewhere twice before for “nasal polyps”, 19 and eight years previously. Anterior rhinoscopy revealed a polypoid lesion in the right nasal cavity. CT showed a mass of the right ethmoidal and sphenoidal sinus with no sign of bone destruction. We performed an endonasal total resection of the tumour. The histological diagnosis was of sinonasal HP. There was no local or remote metastasis. Histological reports of the earlier surgeries were compared and identified the same tumour.ConclusionsThe presented case shows a long-term benign course of recurrent sinonasal HP following endonasal resection. After more invasive approaches, such as lateral rhinotomy, local recurrence has been reported to appear within comparable periods of time. If the tumour is of limited extension, without infiltration of neighbouring structures, it can be removed via an endonasal approach

Amount of substance and the mole in the SI

Abstract Following the revision of the International System of Units (SI), that takes effect on 20 May 2019, the unit mole is defined by using a fixed number of elementary entities. This number is the fixed numerical value of the Avogadro constant, which is the defining constant of the unit mole. This definition was made possible because the determination of the Avogadro constant had reached a level of relative uncertainty that allowed its value to be fixed and, at the same time, safeguard continuity of measurement results before and after the definition. The motivation for the revision of the SI and the mole in particular will be explained and the experimental work that allowed it is summarized

CCQM-K90, formaldehyde in nitrogen, 2 μmol mol− 1 Final report

The CCQM-K90 comparison is designed to evaluate the level of comparability of national metrology institutes (NMI) or designated institutes (DI) measurement capabilities for formaldehyde in nitrogen at a nominal mole fraction of 2 μmol mol−1. The comparison was organised by the BIPM using a suite of gas mixtures prepared by a producer of specialty calibration gases. The BIPM assigned the formaldehyde mole fraction in the mixtures by comparison with primary mixtures generated dynamically by permeation coupled with continuous weighing in a magnetic suspension balance. The BIPM developed two dynamic sources of formaldehyde in nitrogen that provide two independent values of the formaldehyde mole fraction: the first one based on diffusion of trioxane followed by thermal conversion to formaldehyde, the second one based on permeation of formaldehyde from paraformaldehyde contained in a permeation tube. Two independent analytical methods, based on cavity ring down spectroscopy (CRDS) and Fourier transform infrared spectroscopy (FTIR) were used for the assignment procedure. Each participating institute was provided with one transfer standard and value assigned the formaldehyde mole fraction in the standard based on its own measurement capabilities. The stability of the formaldehyde mole fraction in transfer standards was deduced from repeated measurements performed at the BIPM before and after measurements performed at participating institutes. In addition, 5 control standards were kept at the BIPM for regular measurements during the course of the comparison. Temporal trends that approximately describe the linear decrease of the amount-of-substance fraction of formaldehyde in nitrogen in the transfer standards over time were estimated by two different mathematical treatments, the outcomes of which were proposed to participants. The two treatments also differed in the way measurement uncertainties arising from measurements performed at the BIPM were propagated to the uncertainty of the trend parameters, as well as how the dispersion of the dates when measurements were made by the participants was taken into account. Upon decision of the participants, the Key Comparison Reference Values were assigned by the BIPM using the largest uncertainty for measurements performed at the BIPM, linear regression without weight to calculate the trend parameters, and not taking into account the dispersion of dates for measurements made by the participant. Each transfer standard was assigned its own reference value and associated expanded uncertainty. An expression for the degree of equivalence between each participating institute and the KCRV was calculated from the comparison results and measurement uncertainties submitted by participating laboratories. Results of the alternative mathematical treatment are presented in annex of this report

Minimum requirements for publishing hydrogen, carbon, nitrogen, oxygen and sulfur stable-isotope delta results (IUPAC Technical Report)

Stable hydrogen, carbon, nitrogen, oxygen and sulfur (HCNOS) isotope compositions expressed as isotope-delta values are typically reported relative to international standards such as Vienna Standard Mean Ocean Water (VSMOW), Vienna Peedee belemnite (VPDB) or Vienna Cañon Diablo Troilite (VCDT). These international standards are chosen by convention and the calibration methods used to realise them in practice undergo occasional changes. To ensure longevity and reusability of published data, a comprehensive description of (1) analytical procedure, (2) traceability, (3) data processing, and (4) uncertainty evaluation is required. Following earlier International Union of Pure and Applied Chemistry documents on terminology and notations, this paper proposes minimum requirements for publishing HCNOS stable-isotope delta results. Each of the requirements are presented with illustrative example

Prevalence of antibodies against Neospora caninum in dogs from urban areas in Central Poland

Neospora caninum is a protozoan parasite which causes abortion in cattle as well as reproduction problems and neurological disorders in dogs. To assess the prevalence of the parasite in urban dogs in the Mazovian Voivodeship, Central Poland, serum samples from 257 dogs were analyzed for the presence of specific IgG antibodies. The examined dogs visited three private veterinary clinics located in Warsaw due to control tests, vaccinations, or other reasons not directly connected with neosporosis. Using ELISA and Western blot, antibodies against the parasite were detected in 56 out of 257 dogs, giving a prevalence of 21.7%. A greater prevalence was observed in female dogs than in males, 28% and 17.3%, respectively, and the differences were statistically significant (p < 0.05). There were no significant differences in seroprevalence of Neospora infection within the age groups (p > 0.05). This study indicates the presence of N. caninum in the Mazovian Voivodeship, in dogs which live in urban areas and exposure of these dogs to the parasite. The fact that seropositive dogs had no contact with cattle confirms the important role of dogs in the parasite’s epidemiology

NAMES

LOTHAR SIEKMANN

NAME FUNCTION SIGNATURE

JCTLM WG2-P-0