The first proficiency testing round 630-IL-1002, was carried out with a Reference Material DMR-180a with reference values obtained by using Gas Chromatography Isotopic Dilution mass spectrometry (GC-IDMS) methods, in which glucose, cholesterol and creatinine were measured. The serum pool was obtained from blood donors and all the analytes were at the normal concentration in Mexican population. The laboratories participants used different field methods to measure the analytes. The Mexican compulsory standard NOM-064-SSA1-1993 "specifications for equipments IVD" requests <5% for reproducibility and accuracy of IVD equipments. The results obtained by field laboratories in the proficiency testing round are compared to the reference value and uncertainty provided by National Metrology Institute (CENAM). The quality of measurements are dependent not only on the laboratory competence but also on the methods used by those commercially available IVD kits. It is concluded that quality assessment of measurements in clinical laboratories should be critically evaluated by using stable and certified reference materials.

The purpose of this work is to present the development of an analytical procedure for the speciation analysis of methylmercury in fish products. The paper is focused on the extraction of the sample, considered as one of the most difficult step in the speciation process, for which quantitative recovery and preservation of the integrity of the species should be considered.

Based on international standard procedures, the degree of unsaturation on biodiesel was evaluated, called iodine value. Two titration techniques were used to determine the iodine value: colorimetric and potentiometric techniques. The uncertainty of measurement was used to evaluate the quality of the results. The potentiometric technique showed better quality in the determination of the iodine value because of its accuracy as well as lower uncertainty result of the measurements, with values between 0,613 g I₂ / 100 g and 1,438 g I₂ / 100 g), compared to the results from the colorimetric technique, with values between 1,61 g I₂ / 100 g and 3,30 g I₂ / 100 g.

The Chemical Metrology Division (Dquim) from National Institute of Metrology, Standardization and Industrial Quality - Inmetro established in 2003 the primary system of pH measurement. The main use of this system is to provide reliability and traceability to the pH measurements in Brazil since its measurement is one of the most important analyses carried out in many laboratories all over the country. In order to show comparability and capability in primary pH measurement, Inmetro participated in both the key-comparisons CCQM-K18 and in the supplementary comparison that followed, named CCQM-K18.1, to measure the pH in a carbonate buffer solution of nominal value of pH 10. Both exercises were organized by Consultative Committee for Amount of Substance (CCQM) of the International Bureau of Weights and Measures (BIPM). This work aimed at showing the development and optimization of the primary pH system from Inmetro in order to participate in the supplementary key-comparison. Inmetro´s results in that supplementary comparison have shown its capability in primary measurement of pH 10.

Soft sensors, based on Elman NNs, have been developed to provide virtual measurements at different locations on the monument surface using as input source only the measurements acquired by an Air Ambient Monitor Station located nearby. Simulation of measurements by trained NN is a useful computational tool to monitor the physical or chemical conditions of the composing materials in a not invasive way, but their accuracy has to be high as analyzed from a metrological and statistical point of view. Two different mathematical and computational tools can be adopted to improve the accuracy of the virtual measurements: a wavelet preprocessing of times series data and the mixture of soft sensors to fuse several input sources.