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Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.2, #8)
Primary methods of measurement in chemical analysis by W. Richter (pp. 354-359).
Primary methods of measurement have a central function in metrology. They are an essential component in the realisation of the SI units and therefore are indispensable for establishing traceability of measurements of all kinds of physical quantities to the corresponding SI units. This is also true for chemical analysis. Gravimetry, titrimetry, coulometry, and isotope dilution mass spectrometry (IDMS) are evaluated with regard to their potential to be primary methods according to a general definition of primary methods recently given by the Comité Consultatif pour la Quantité de Matière (CCQM). Optical absorption spectrometry and methods based on colligative properties are also considered. A general scheme for establishing traceability of chemical measurements to the SI units using primary methods is discussed.
Keywords: Key words Traceability to SI; Primary methods; Comparability
Qualification and validation of software and computer systems in laboratories by L. Huber; Herbert Wiederoder (pp. 360-366).
Software and computer systems are tested during all development phases. The user requirements and functional specifications documents are reviewed by programmers and typical anticipated users. The design specifications are reviewed by peers in one to two day sessions and the source code is inspected by peers, if necessary. Finally, the function and performance of the system is tested by typical anticipated users outside the development department in a real laboratory environment. All development phases including test activities and the final release follow a well-documented procedure.
Keywords: Key words Validation; Qualification; Computers; Software; Analytical; Laboratories
Improved calibration for wide measuring ranges and low contents by Michael Karl Walter Huber (pp. 367-374).
Homogeneous regression offers considerable advantages for calibration purposes as compared with the more usual linear regression of a general straight line, provided that the criteria for the use of the method are complied with. The calibration range can be increased, the amount of work involved in the calibration can be reduced, and the limit of detection can be considerably decreased. For high contents the more usual method is to be preferred, as it gives more precise results.
Keywords: Key words Calibration; Wide range; Detection limit; Homogeneous regression
Clinical reference materials for the validation of the performance of photometric systems used for clinical analyses by M. Buzoianu; H. Y. Aboul-Enein (pp. 375-380).
There are a wide variety of spectrophotometric devices nowadays used in health services with various qualities of manufacture methods of measurement and metrological characteristics for performing the necessary measurements. Therefore, to meet the accuracy and repeatability requirements needed in medical diagnosis and treatment, the validation of the performance of such systems by clinical chemistry laboratories is essential. However, the validation of a spectrophotometric system for clinical analyses requires several reference materials, according to the end use of the measurement results. This paper discusses some characteristics required of the clinical reference materials needed and used by Romanian Institute of Metrology for validation work. Types of clinical reference materials developed in the national area for this purpose are also presented.
Keywords: Key words Clinical spectrophotometry; Quality assurance; Validation; Reference materials; Spectrophotometric standards
Problems of validation of computerised instruments for accredited chemical laboratories by Z. Dobkowski (pp. 381-387).
Some problems of validation of computerised instruments are reviewed briefly, taking essential standards and guides into account. The significant role of certified standard reference materials is underlined. An attitude of suppliers towards the validation of instruments is presented, and producers' responsibilities and obligations are discussed. The "black-box" concept is recommended as a preliminary step for the validation of computerised instruments. Two examples for gel permeation chromatography are given that illustrate a bad manufacturer's practice (BMP) and good manufacturer's practice (GMP). In the case of BMP, a need is expressed for a guide and for regulations that should be implemented into the quality assurance system. It has been proposed that the EURACHEM/VAM draft of guidance for qualification/validation of instruments should be amended by incorporating the "black-box" approach as a preliminary procedure for validation of computerised instruments, a retrospective validation procedure if the need for current validation was not foreseen or not specified, and a procedure (or selection rules) for qualification of the supplier. Moreover, the mechanisms of inspection to control the observance of the standardised rules and commonly recognised recommendations should also be considered by international quality organisations.
Keywords: Key words Validation of computerised instruments; Black-box concept for validation