A quality systems approach for identifying and controlling sources of error with point of care testing devices

Historically, due to the size and nature of the instrumentation, highly skilled laboratory professionals performed clinical testing in centralized laboratories. Today’s clinicians demand realtime test data at the point of care. This has led to a new generation of compact, portable instruments permitting ”laboratory” testing to be performed at or near the patient’s bedside by nonlaboratory workers who are unfamiliar with testing practices. Poorly controlled testing processes leading to poor quality test results are an insidious problem facing point of care testing today. Manufacturers are addressing this issue through instrument design. Providers of clinical test results, regardless of location, working with manufacturers and regulators must create and manage complete test systems that eliminate or minimize sources of error. The National Committee for Clinical Laboratory Standards (NCCLS) in its EP18 guideline, ”Quality management for unit-use testing,” has developed a quality management system approach specifically for test devices used for point of care testing (POCT). Simply stated, EP18 utilizes a ”sources of error” matrix to identify and address potential errors that can impact the test result. The key is the quality systems approach where all stakeholders – professionals, manufacturers and regulators – collaboratively seek ways to manage errors and ensure quality. We illustrate the use of one quality systems approach, EP18, as a means to advance the quality of test results at point of care. Received: 26 June, 2002 Accepted: 17 July 2002 Presented at the European Conference on Quality in the Spotlight in Medical Laboratories, 7–9 October 2001, Antwerp, Belgium Abbreviations NCCLS National Committee for Clinical Laboratory Standards (formerly) · POCT point of care testing · QC quality control · HACCP hazard analysis critical control points · CLIA clinical laboratory improvement amendments (of 1988) Correspondence to S. S. Ehrmeyer     

Evaluation of the use of consensus values in proficiency testing programmes

Proficiency testing (PT) is an essential tool used by laboratory accreditation bodies to assess the competency of laboratories. Because of limited resources of PT providers or for other reasons, the assigned reference value used in the calculation of z-score values has usually been derived from some sort of consensus value obtained by central tendency estimators such as the arithmetic mean or robust mean. However, if the assigned reference value deviates significantly from the ‘true value’ of the analyte in the test material, laboratories’ performance will be evaluated incorrectly. This paper evaluates the use of consensus values in proficiency testing programmes using the Monte Carlo simulation technique. The results indicated that the deviation of the assigned value from the true value could be as large as 40%, depending on the parameters of the proficiency testing programmes under investigation such as sample homogeneity, number of participant laboratories, concentration level, method precision and laboratory bias. To study how these parameters affect the degree of discrepancy between the consensus value and the true value, a fractional factorial design was also applied. The findings indicate that the number of participating laboratories and the distribution of laboratory bias were the prime two factors affecting the deviation of the consensus value from the true value.     

The Australian perspective

This presentation deals with issues of comparability and traceability in food analysis in Australia from several perspectives. This includes the current national (Australian) and increasingly international (Codex) performance-based approach to food analysis. The Australian food regulatory process will be described, particularly those aspects that impact on the analysis of food in a regulatory sense. This section will also describe two areas where specific methods have been mandated in legislation and discuss two case studies where the analytical method has impacted on the elaboration of standards. Other areas to be covered include regulation/requirements relating to supply/availability of reference materials, the use of proficiency testing as a means of ensuring comparability, and, finally, some thoughts on what role BIPM/CCQM may play in the analysis of food.Electronic Supplementary Material  Supplementary material is available for this article at

Uncertainty assessment from robustness testing applied on an LC assay for R-timolol and other related substances in S-timolol maleate

The robustness testing of a normal-phase liquid chromatographic (LC) method for the determination of R-timolol and other related substances in S-timolol maleate was performed applying a two-level Plackett-Burman design. Two qualitative and five quantitative factors were examined. Two types of responses were considered, qualitative, i.e. chromatographic performance criteria, and quantitative ones. The latter were taken into account to determine if the analytical procedure was robust. The quantitative responses were the contents of R-timolol in two S-timolol maleate samples. Even though some significant factor effects were observed on the qualitative responses, the R-timolol contents were not significantly different from those observed at nominal conditions, which demonstrated the robustness of the procedure.Since the experiments of the Plackett-Burman design can be assimilated to laboratories in an interlaboratory study, uncertainty can be evaluated using the robustness test data. The robustness test was set-up in such a way that the required variances could be estimated. It was shown that the robustness set-up allows estimating the reproducibility uncertainty without performing an interlaboratory study.     

Electrodeposition of a cobalt-molybdenum alloy from an ammonia-citrate electrolyte

Kinetics of processes of electrochemical production of a cobalt-molybdenum alloy out of an ammonia-citrate electrolyte is studied. The electrolyte’s composition is similar to that used for depositing a nickel-molybdenum alloy. It is established that the cobalt-molybdenum alloy undergoes deposition at smaller values of pH (5.0–6.0) than the nickel-molybdenum alloy (7.0–9.0). The current efficiency for the cobalt-molybdenum alloy is substantially dependent on the electrolyte pH, whereas the chemical composition of the obtained deposits is practically independent of the electrolyte pH in the pH interval 5.0–8.0 at current densities of 0.025 to 0.100 A cm^?2. On the other hand, a change in the electrolyte pH produces a considerable effect on the morphology of the obtained deposits. At large values of pH (pH 8.0), one can obtain a powder-like deposit of the cobalt-molybdenum alloy with a small value of the current efficiency. The deposits that are obtained in the pH region 5.0–6.0 have some cracks, with the number of cracks increasing with the electrolyte pH.     

Practical capillary gas chromatography—a systematic approach

Capillary gc is now rapidly expanding. Naturally, initiation is most often attempted on the basis of the experience acquired with packed columns. However, such an extrapolation is successful only if a number of essential peculiarities of capillary gc are considered. Based on practical examples this paper discusses six essential details: 1) design and maintenance of the gas flow paths, 2) the greatly increased importance of sampling technique, which should not be confined just to stream splitting, 3) the problems in quantitative analysis arising from small sample size, 4) specific sources of trouble related to small amounts of liquid phase, 5) specific arguments for the choice of the carrier gas, clearly pointing to hydrogen as the ideal carrier and, 6) the different way to approach column production. Figures for all selected examples are given.     

Analysis of dissolution test sample solutions by high speed capillary electrophoresis

Summary The quantitative use of high speed capillary electrophoresis (HSCE) is examined by applying high voltages across short capillaries. Acceptable performance in terms of injection precision and migration times were achieved within 1–2 minute analysis times. HSCE was used for the novel CE application of dissolution test sample solution analysis. The results generated by HSCE compared well with those generated using validated on-line UV absorbance measurements. It is concluded that HSCE is a viable alternative and supplement to standard analytical methods employed in dissolution test analysis.     

Thermal analysis of the cruciate ligaments of the human knee

Summary Cruciate ligaments of the knee joint are important structures very often affected by the degenerative process in case of osteoarthritis. One of the most controversial issues in knee arthroplasty practice nowadays is the role of the posterior cruciate ligament. With foregoing studies authors have demonstrated the feasibility of DSC in the investigation of the musculoskeletal system. With current study authors established the thermal behaviour of healthy cruciate ligaments and detected the alterations in case of osteoarthritis. By establishing the DSC scans of the normal ligaments authors demonstrated clear differences between the posterior and anterior ligament. In addition alterations between normal and arthritic samples could be detected both in terms of changes in total enthalpy and heat capacity. Calorimetric findings have been verified by histological examinations as well.     

Additives for the reduction of sulfur in FCC gasoline

Sulfur reduction ability of alumina supported zinc, gallium and zinc-gallium additives for fluid catalytic cracking catalysts was evaluated in a micro-activity test unit (MAT). Gallium/alumina showed the highest sulfur reduction of 31%, but the cracking activity of the catalyst was decreased. Zinc-gallium/alumina reduced sulfur in 24 wt.% without decreasing the base catalyst activity.     

Multivariate analysis of non-homogeneous peaks in liquid chromatography

Summary The effects of concentration, separation and spectral similarity as factors influencing the accuracy of iterative target testing factor analysis (ITT-FA) are investigated for three component systems by the application of analysis of variance (ANOVAR). ANOVAR is applied over a range of peak separations to map the changing effects of the three factors with increasing overlap. Two error responses were measured and analysed, (a) Relative cluster error (RCE) a measure of the error over all peaks in a cluster and (b) Relative peak error (RPE) the error of an individual peak. Multicomponent analysis (MCA) a method requiringa priori spectral information, is used as a referee method for ITT-FA.