On practical metrology and chemical analysis: legal,institutional and technical evolutions in the Australian national measurement system

 Economic and technological change, regional and international trade and the globalisation of industry have led to intense pressures for improvements to analytical quality, reliability and comparability. Of central importance are national traceability structures connecting chemical measurements in the field with internationally accepted measurement units and their practical realisations. Australia has a developed physical and engineering measurement system, a legislative framework for analytical traceability and, in the National Association of Testing Authorities, a recognised laboratory accreditation system. The need has been identified to develop the technical capability to perform matrix-independent reference measurements for the certification of traceable reference materials, useable as practical analytical etalons to establish metrological control systems in field measurements for amounts of substance. Recently, a unique collaborative consortium has proposed a National Analytical Reference Laboratory (NARL). The NARL is designed to be a metrological mass spectrometry facility for the transference of measurement units to more widely useable chemical measurement standards and reference materials. Received: 10 October 1995 Accepted: 26 October 1995     

Radioactive ion beams--global scenario and national efforts

The availability of Radioactive Ion Beams (RIBs) will signal the dawn of a new era in heavy-ion science. In this context, a brief overview of the scientific motivation and the technological challanges to be overcome for building RIB facilities are discussed in this article. The activities in this direction being presently carried out globally are presented briefly with special emphasis on Indian efforts.     

Temperature measurement and control

Several factors in temperature measurement that can affect the precision of melting points and phase-change phenomena are discussed. In many cases, critical errors may arise in the measurement and control of temperatures due to incorrect placement and/or interpretation of the output of temperature sensors in the various system types that are in current use. Advantages can be obtained by using one temperature sensor only for temperature measurement and temperature control in a low mass infrared gold image fumace for the analytical studies in both the constant rate and stepwise isothermal thermoanalytical heating and cooling modes. Illustrations of the use of this instrumentation for measurements in both modes are given.     

Radon measurement uncertainty: Comparison between passive short-term and active measurement

The measurement of indoor ²²²Rn is not as straightforward as commonly perceived. The most commonly used measurement method is a passive, short-term device using activated charcoal that collects gases, typically for 3–7 days. Short-term measurements are popular because a radon determination is often required by a homebuyer and the buying transaction needs to be completed within 30–60 days. From deployment to obtaining the result from a laboratory reading the passive short-term device can take about 2 weeks. Active measurements, in which a portable alpha-particle counter is placed within a house and air pumped through a scintillation cell have been compared to passive short-term measurements and found to be consistent. For transactions requiring faster or immediate results, active counting methods appear to be a reliable method for measurement.     

Uncertainty of measurement and legislative limits

 The uncertainty affecting analytical measurements has to be taken into account when evaluating compliance of suspect matrices to legislative limits. To this aim Type 1 and 2 errors must be considered. This necessarily leads to the evaluation of the minimum detectable inadmissible signal, from which the minimum detectable inadmissible concentration can be obtained. The signal of suspect matrices thus has to be compared with the minimum detectable inadmissible signal. This paper aims to discuss practical problems involved in the comparison.     

Voltammetric measurement of reduced nicotinamide-adenine nucleotides and application to amperometric measurement of enzyme reactions.

The electrochemical oxidations of reduced nicotinamide-adenine dinucleotide and reduced nicotinamide-adenine dinucleotide phosphate on platinum and carbon electrodes are described. Well defined voltammetric anodic waves are observed on carbon electrodes, with a linear relationship between peak height and concentration for 0–0.5mM NADH and NADPH. Amperometric methods for NAD oxidoreductase analyses by direct electrochemical oxidation of the reduced nucleotide have been developed for lactic dehydrogenase and ethanol in serum.     

Purity verification and measurement uncertainty

In chemical analysis, laboratories are required to verify the purity of reference material being used. Also, the contributions from the verification procedure, where significant, have to be included in the estimation of the total measurement uncertainties of the test results. One common verification procedure is to use another source of the same material if an appropriate certified reference material were not available. This involves a comparison test where the purity value of the reference standard is determined using a second source reference standard as the “calibrant”. In normal practice, the standard uncertainty of the purity value of a reference standard is estimated according to the probability distribution function (PDF) of the possible purity values of the reference standard concerned. With the use of Monte Carlo simulation technique, this paper attempted to study the effect of verification process on that PDF and thus the associated standard uncertainty as well. Also, the effects of parameters like the purity of the second source reference standard, the method precision and the acceptable range set for the comparison test on the verification outcome were discussed.     

Quantum computing measurement and intelligence

One of the grand challenges in the nanoscopic computing era is guarantees of robustness. Robust computing system design is confronted with quantum physical, probabilistic, and even biological phenomena, and guaranteeing high‐reliability is much more difficult than ever before. Scaling devices down to the level of single electron operation will bring forth new challenges due to probabilistic effects and uncertainty in guaranteeing “zero‐one” based computing. Minuscule devices imply billions of devices on a single chip, which may help mitigate the challenge of uncertainty by replication and redundancy. However, such device densities will create a design and validation nightmare with the sheer scale. The questions that confront computer engineers regarding the current status of nanocomputing material and the reliability of systems built from such minuscule devices are difficult to articulate and answer. This article illustrates and discusses two types of quantum algorithms as follows: (1) a simple quantum algorithm and (2) a quantum search algorithm. This article also presents a review of recent advances in quantum computing and intelligence and presents major achievements and obstacles for researchers in the near future. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Use of a capacitance measurement device for surrogate noncontact conductance measurement

A capacitance to digital converter (AD7746) is used in the same mode as noncontact conductance detectors. The detector output is linearly proportional to specific conductance (sigma) at low sigma values but becomes nonlinear and reaches a plateau value at sigma approximately >0.75 mS/cm, regardless of the nature of the electrolyte. For all applications at sub- to low-mM concentrations, the device, available as an evaluation board, provides a very affordable nothing-else-required means of contactless surrogate conductivity detection from capillary scale to larger bore conduits. For the same measurement cell volume, the detector provides virtually the same limits of detection (LODs) as a standard galvanic contact conductivity detector in conventional scale suppressed conductometric ion chromatography. The detection limits deteriorate as the conduit inner diameter decreases.     

On the specific experience of national metrology institutes (NMIs) with national accreditation bodies (NABs)

The following paper addresses the experience of certain national metrology institutes (NMIs) with national accreditation bodies (NABs), in particular in small countries with emerging economies in new EU or candidate member states. Specific cases have been analysed primarily in some Central and South-East European countries. NABs under consideration are, in principle, members of European Co-operation for Accreditation (EA). EA cross-frontier policy in these cases will be discussed and resulting dilemmas outlined. Focus will be given to the problems of NMIs also performing calibrations, commercial calibration laboratories, and their relations with NABs. Due to numerous problems of smaller NABs, cross-frontier policy should stimulate cooperation between foreign and local accreditation bodies not only at the request of the calibration laboratory or some other conformity assessment body, but at the request of the local accreditation body in order to provide the best service for their local economy. As a solution to the accreditation problems, this paper proposes a process of gradual formation of a common European pool of experts, real-life common practices and, finally, maybe even some form of joint European accreditation service. The opinions expressed in the paper are personal statements of the author, and do not necessarily reflect the official opinions of the institutions of the author. Papers published in this section do not necessarily reflect the opinion of the Editors, the Editorial Board and the Publisher.