Regulatory compliance vs. NEXUS quality for laboratory tests

In the U.S., all clinical laboratory testing is regulated by the Clinical Laboratory Improvement Amendments (CLIA) (). The CLIA link test quality and adherence to a body of testing regulations intended to ensure accurate, reliable, and timely patient test results. The goal of the CLIA legislation was to ensure a minimum, fundamental level of quality. In the context of “NEXUS,” quality must “go beyond getting the ‘right’ answer on the ‘right’ patient that can be interpreted against ‘right’ reference values. CLIA regulations with specific minimum, performance requirements, or safeguards, are designed to prevent testing errors. The US Institute of Medicine found that testing processes fail as a result of human error, lack of documentation, and lack of test management. In the latest (2004) interpretations of CLIA regulations, the minimum quality control requirement continues to be analyzing at least two external, liquid quality control materials per test per day. In 1995, we proposed that the responsibility for achieving quality test results shifts from the sole purview of the laboratory director to an “alliance” of laboratory professionals, manufacturers, and regulators. The EQC (equivalent quality control) concept as proposed is a positive step in achieving this alliance. With the obvious lack of scientific and statistical robustness, EQC falls far short of ensuring quality. Achieving the “NEXUS Vision” for quality laboratory testing will not come solely from laboratory professionals. The NEXUS is about how to ensure the full-quality assessment of the testing process – pre-analytical, analytical, and post-analytical.Presented at the 10th Conference Quality in the Spotlight, March 2005, Antwerp, Belgium.     

New advances in method validation and measurement uncertainty aimed at improving the quality of chemical data

The implementation of quality systems in analytical laboratories has now, in general, been achieved. While this requirement significantly modified the way that the laboratories were run, it has also improved the quality of the results. The key idea is to use analytical procedures which produce results that fulfil the users needs and actually help when making decisions. This paper presents the implications of quality systems on the conception and development of an analytical procedure. It introduces the concept of the lifecycle of a method as a model that can be used to organize the selection, development, validation and routine application of a method. It underlines the importance of method validation, and presents a recent approach based on the accuracy profile to illustrate how validation must be fully integrated into the basic design of the method. Thanks to the -expectation tolerance interval introduced by Mee (Technometrics (1984) 26(3):251–253), it is possible to unambiguously demonstrate the fitness for purpose of a new method. Remembering that it is also a requirement for accredited laboratories to express the measurement uncertainty, the authors show that uncertainty can be easily related to the trueness and precision of the data collected when building the method accuracy profile.     

Organic coffee discrimination with INAA and data mining/KDD techniques: new perspectives for coffee trade

Samples of green coffee (Coffea arabica) produced in the crop year 1999/2000 in Minas Gerais state, Brazil, were analyzed for the elements Al, Ba, Br, Ca, Cl, Co, Cs, Cu, Fe, K, Mg, Mn, Na, Rb, S, Sc, and Zn using instrumental neutron activation analysis (INAA), in an attempt to establish fingerprints of organically grown coffee. Using data mining/KDD techniques the elements Br, Ca, Cs, Co, Mn, and Rb were found to be suited as markers for discrimination of organic from conventional coffees. Received: 12 April 2002 Accepted: 31 July 2002 Acknowledgments The authors wish to thank the financial support supplied by FAPESP and CNPq; and TUDelft for granting a research fellowship to Mr. Tagliaferro. Thanks are also given to MINASCOFFEE for supplying the coffee samples, and to an anonymous referee for valuable comments.     

EFFECT OF THE COMPOSITION OF m-CRESOL/H2O SOLVENT ON HYDRODYNAMIC PROPERTIES OF NYLON 6

The intrinsic viscosity [ η], Huggins constant (KH), [ η]0, α3 and flow activation energy values of nylon 6 have been measured in water/m-cresol (0/100-20/80) systems at different temperatures (20-60℃). It has been found that the intrinsic viscosity, [η]0 and α3 increase with the increase in water contents in m-cresol up to 15% and then decrease. They increase with the increase in temperature irrespective of solvent composition. It has been noted that the percent increase of α3 is the highest at 60℃ and the lowest at 20℃ for a particular solvent system. The intrinsic viscosity data obey Arrhenius equation over the considered conditions. The activation energy and the KH values decrease very sharply with the addition of water,giving a minimum value at 15% of water and then increase slowly. The variation of all the parameters has been explained in terms of variation in thermodynamic quality of solvent with the addition of water to m-cresol and change in temperature,resulting in the change of conformational and orientational properties of polymer molecules. This change of solvent quality also results in variation of selective sorption of solvent over the polymer, such as hydrogen bonding, etc.     

The measurement of molecular diversity by receptor site interaction simulation

The assembly of large compound libraries for the purpose of screening against various receptor targets to identify chemical leads for drug discovery programs has created a need for methods to measure the molecular diversity of such libraries. The method described here, for which we propose the acronym RESIS (for Receptor Site Interaction Simulation), relates directly to this use. A database is built of three-dimensional representations of the compounds in the library and a set of three-point three-dimensional theoretical receptor sites is generated based on putative hydrophobic and polar interactions. A series of flexible, three-dimensional searches is then performed over the database, using each of the theoretical sites as the basis for one such search. The resulting pattern of hits across the grid of theoretical receptor sites provides a measure of the molecular diversity of the compound library. This can be conveniently displayed as a density map which provides a readily comprehensible visual impression of the library diversity characteristics. A library of 7500 drug compounds derived from the CIPSLINEPC databases was characterized with respect to molecular diversity using the RESIS method. Some specific uses for the information obtained from application of the method are discussed. A comparison was made of the results from the RESIS method with those from a recently published two-dimensional approach for assessing molecular diversity using sets of compounds from the Maybridge database (MAY).     

Polymer crystallization dynamics,as reflected by differential scanning calorimetry. Part 1: On the calibration of the apparatus

In this paper a method for the calibration of the heat transfer coefficient between pan and furnace is given. This (second) calibration is necessary in addition to the usual calibration of the temperature scale. Indeed, with increasing cooling rates as required for kinetic measurements, the finite heat flow resistance between pan and furnace becomes evident anyway. We also propose to enlarge this resistance deliberately, in order to separate the time scales of the control system and of the exponential return of the heat flow curve to the base line, as occurring after completion of the phase transition. Only in this way can the heat transfer coefficient be determined with some accuracy. Another advantage of a lowered heat transfer coefficient will be treated in a third paper. It enables an approximate treatment of polymer crystallization kinetics.     

Implementation of a ”data filter” for the UK National Marine Monitoring Programme

The implementation of a strategy for the assessment of the validity of environmental monitoring data – a ”data filter”– is described. The approach was developed through the UK National Marine AQC Scheme for application to data collected during the UK National Marine Monitoring Programme. Data reported for the year 1999, by nine laboratories, for 74 determinand-matrix combinations were assessed on the basis of the completeness of their supporting quality assurance and quality control information. The approach to the establishment of criteria of acceptability for quality information is described. Received: 28 August 2001 Accepted: 29 November 2001     

Remarks about separately convex functions

This paper shows the property of weak lower semicontinuity of separately convex integrands under more general hypothesis than boundedness inL ² of partial derivatives, and some properties of the parametrized measures associated with such sequences.This research was partially supported by DGICYT (Spain) through Programa de Perfeccionamiento y Movilidad de Personal Investigador and through Grant PB 90-245.     

实现标准物质量值溯源性的初步探讨

叙述了研究标准物质量值溯源性的必要性,讨论了实现标准物质量值溯源性的基本途径及技术难点。指出了量值溯源的关键是对定值方法和分析过程质量保证技术进行系统的研究。     

A global indicator as a tool to follow airborne molecular contamination in a controlled environment

The impact of pollutants on production quality in nanotechnology necessitates reduction of contaminant levels in cleanrooms. So, devising a global airborne-pollutant indicator (GAPI) for rapid determination of the level of pollution and its danger to the process is justified. This tool used relative impact weights of the different molecules to quantify the pollution. A calculation of impact weight is proposed in this paper. Impact weights could take into account several characteristics of the molecules (molecular volume, sticking coefficient, ...). They could also be combined to be as close as possible to reality. An example of calculations of the impact of molecular volumes on air quality is given.