This paper describes a quantum realization of the pascal based a helium absolute refractometer at 532 nm. The short-term stability in pressure is ± 2 mPa with a resolution in pressure of this new optical pressure standard is better than 1 mPa with temperature stability about 1 mK. A new design of the refractometer is presented to have better temperature stability and accurate temperature measurements to reach uncertainties in pressure better than current conventional methods.
Six European metrological institutes compared their calculation methods, and estimated uncertainties, resulting in the derivation of the effective area A 0 (20˚C, p atm) of six piston-cylinder assemblies routinely in use in pressure balances that are primary standards of the pressure laboratories, operating in different pressure ranges in gas (up to 1 MPa) and in liquid (up to 1 GPa). The results for A 0 and its standard uncertainty u(A 0) are presented and compared.
A study was carried out to evaluate the analytical capabilities of coupling chemical bromide generation with inductively coupled plasma atomic emission spectrometry for the determination of selenium in both oxidation states, VI and IV. The method is based on the generation of two volatiles of selenium(VI) and (IV) by reaction with bromide ions in sulfuric acid media in a discontinuous mode and transport of the gaseous phase to the plasma torch. After evaluation of the main and interactive effects of the experimental variables by experimental design the three most influential variables were optimized for each determination by the modified Simplex method. The volatilization efficiency of both volatile species was determined. The mean of six experiments gave volatilization efficiencies of 73 and 77% for Se VI and Se IV , respectively. Under the optimized analytical conditions selenium can be determined after volatilization of Se VI with an absolute detection limit (3s) of 0.25 ng for the injection of 200 ml of the sample solution. The precision (RSD) was 2% for the injection of five replicates of 2.0 ng of Se VI (200 ml of a 0.1 mg ml 21 solution). Again under optimized conditions for Se IV , like Se VI , an absolute detection limit for selenium of 0.31 ng with a reproducibility (RSD) of 6.8% was obtained. The interference of common anions and cations on the selenium signal of both states (VI and IV) was evaluated. The Se VI method was applied to the determination of selenium in cosmetic gel shampoos and the method for Se IV was applied to the determination of selenium in dietetic compounds. The results were validated in both cases by using alternative methods.
This report describes a EURAMET comparison of five European National Metrology Institutes in low gauge and absolute pressure in gas (nitrogen), denoted as EURAMET.M.P-K4.2010. Its main intention is to state equivalence of the pressure standards, in particular those based on the technology of force-balanced piston gauges such as e.g. FRS by Furness Controls, UK and FPG8601 by DHI-Fluke, USA. It covers the range from 1 Pa to 15 kPa, both gauge and absolute. The comparison in absolute mode serves as a EURAMET Key Comparison which can be linked to CCM.P-K4 and CCM.P-K2 via PTB. The comparison in gauge mode is a supplementary comparison.
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