Laboratory performance studies

DE Boer J and Wells DE (1996) The 1994 QUASIMEME laboratory performance studies chlor-obiphenyls and organochlorine pesticides in fish and sediment. Mar Poll Bull 32 654-666. 

Laboratory performance study. Laboratories use the method of their choice to measure one or more quantities on one or more homogeneous and stable test samples in order to assess the performance of the laboratory or analyst. The reported results are compared among themselves, with those of other laboratories, or with the known or assigned reference value, usually with the objective of evaluating or improving laboratory performances (IUPAC Orange Book [1997, 2000]). 

Proficiency testing is a special type of laboratory performance studies defined as study of laboratory performance by means of ongoing interlaboratory test comparisons (ISO Guide 33 [1989] ISO/REMCO N 280 [1993] IUPAC [1993] Prichard et al. [2001]). Proficiency testing is an essential part of external quality assessment schemes and performance checks. 

Uhlig, S and Lischer, P (1998), Statistically-based performance characteristics in laboratory performance studies. Analyst, 123, 167—72. 

Lioy, P.J., T. Wainman and C. Weisel (1993). A wipe sampler for the quantitative measurement of dust on smooth surfaces Laboratory performance studies, 7. Exp. Anal. Environ. Epidem., 3, 315-330. 

Collaborative study Consensus value Interlaboratory study Laboratory performance study... 

Laboratory performance study An interlaboratory study that consists of one or more measurements by a group of laboratories on one or more homogeneous, stable, test samples by the method selected or routinely used by each laboratory. The reported results are compared with the consensus value. Note, this is very similar to a Proficiency Testing scheme (see below). 

QUASIMEME Laboratory performance studies, Round 14, DE-2 Exercise 379. Toxaphene Development Exercise, Aberdeen, UK, January 1999... 

QUASIMEME, 2000. Laboratory performance studies. Round 19, DE-6, Exercise427. Chlorophyll a in seawater. January-February 2000. 

Before participating in interlaboratory studies the laboratory must have set-up all adequate internal quality assurance and quality control systems [7]. This also means that all basic investigations have been performed for possible mistakes, that these have been noticed and corrected. In other words the laboratory has validated the method to be applied. For a laboratory performance study, this also implies that in the laboratory the method is under statistical control for a given type of matrix, that this control is monitored and that results are evaluated. 

CRMs should not be used in large collaborative laboratory performance studies. 

It is a study, which focuses on the performance of the laboratory and of the analyst. Several examples of such studies are described in literature [42,43]. It helps participants to compare their performance and their method to the performance of other laboratories and/or to an assigned value [44,45]. Repetitive laboratory performance studies to evaluate if laboratories are able to fulfil a given task are often called proficiency testing schemes. First guidelines have been set under the ISO Guide 43 [46]. In 1993, lUPAC has published an international harmonised protocol for the proficiency testing of (chemical) analytical laboratories [3] which sets the basic criteria for the organisation of laboratory performance studies. 

Laboratory performance studies are organised by private or public entities. Participation can be done on a voluntary basis (e.g. by subscription). It may be mandatory when the laboratory seeks for a special recognition or social status e.g. accreditation. The number of participants may vary from some 20 e.g. for some very specialised measurements such as doping control laboratories of the International Olympic Committee (IOC) to nearly hundred or more, e.g. in the case of the QUASI M EM E project described in section 12.5.6. 

This part of the laboratory performance study is probably the most sensitive to the participants. The responsible of the evaluation may have to draw consequences from the achieved performance for the various participants. To assume this responsibility he needs to be scientifically competent. The organiser should also ensure that the data have been produced without any collusion of participants or falsification. Depending on the number of participants, the objective and the consequences of the study and the frequency of the trials, preservative measures against collusion may be taken (e.g. different and coded sets of test samples, etc). Whatever, it must remain clear to the participants that laboratory performance studies are first of all organised to help them to reach and maintain quality for the benefit of ail. 

Example of Laboratory Performance Study Proficiency testing scheme for marine monitoring... 

QUASIMEME Project office (1998) QUASIMEME laboratory performance studies Jime 1996-May 1997, QUASIMEME Bulletin No. 5. QUASIMEME Project Office, Aberdeen... 

Proficiency testing or laboratory performance study or round-robin study Cooperative trial... 

In the field of polymer/additive analysis a rather limited number of other laboratory performance studies is available. Recently, the Swiss Eederal Laboratories for Materials Testing and Research (EMPA, St. Gallen) has organised a series of interlaboratory tests on polymeric materials, examining the glass transition point by DSC (amorphous thermoplastics), antioxidant content in polyolefins. 

Steaming of fresh catalyst samples for laboratory performance studies has been done in fixed or fluidized bed units. Several factors such as temperature, steam partial pressure and total time of the treatment can influence the final results. The catalyst can be steamed in the presence of 100% steam or as low as 10%. Temperature can vary from 500 C to 850 C, pressures from 1 to 3 atm and steaming times from 2 to 36 hours. There seems to be no consistent agreement on the optimum conditions to be used with most researchers finding appropriate conditions based on equipment available and the catalyst used. 

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