Comparisons interlaboratory

Relyea, J.F. Serne, R.J. "Controlled Sample Program Publication Number 2 Interlaboratory Comparison of Batch Kj Values", Report PNL-2872, Battelle Pacific Northwest Laboratory, 1979. 

A number of handbooks and monographs are available with detailed descriptions of a variety of plant products and their use (Shahidi and Naczk, 1995). From a more practical point of view, an interlaboratory comparison between six university and industry laboratories of 17 extracts of spices, teas, coffees, and grape skin and of tomato peel slurry established within the framework of an EU sponsored programme, would be of interest (Schwarz et al, 2001). In this collaboration, detailed chemical analysis of the content of different phenolic compounds is compared with six antioxidant assays for the 17 extracts including different extraction procedures. 

Saurer M, I Robertson, R Siegwolf, M Leuenberger (1998) Oxygen isotope analysis of cellulose an interlaboratory comparison. Anal Chem 70 2074-2080. 

In case of fast gradient (below 15 min), S could be considered constant for all the investigated molecules and wiU only have a small influence on the retention time of the compounds. Thus, the gradient retention times, of a calibration set of compounds are linearly related to the ( )o values [39]. Moreover, Valko et al. also demonstrated that the faster the gradient was, the better the correlation between t, and < )o [40]. Once the regression model was established for the calibration standards, Eq. 8 allowed the conversion of gradient retention times to CHI values for any compound in the same gradient system. Results are then suitable for interlaboratory comparison and database construction. The CH I scale (between 0 and 100) can be used as an independent measure of lipophilicity or also easily converted to a log P scale. 

Kucera j, Mader P, Miholova D, Cibulka J, Faltejsek J and Kordik D (1995) Preparation of the bovine kidney and bovine muscle reference materials and the certification of element contents fi om interlaboratory comparisons. Fresenius J Anal Chem 352 66-72. 

Sharpless KE, Gill LM, Margolis SA, Wise SA, Elkins E (1999) Preparation of standard reference material 2383 (baby food composite) and use of an interlaboratory comparison exercise for value assignment of its nutrient concentrations. J AOAC Inti 82 276-287. 

Kucera j (1995) Elemental characterization of new Polish and US NIST geological, environmental and biological reference materials by neutron activation analysis and comments on the methodology of interlaboratory comparisons. Chem Anal (Warsaw) 40 405-421. 

It must be remarked that terminology is not consistent and there are many widely used synon)ms. Quality control in this Chapter refers to practices best described as internal quality control. Quahty assessment is often referred to as external quality control, proficiency testing, interlaboratory comparisons, round robins or other terms. Internal Quality Control and External Quality Assessment are preferred because they best describe the objectives for which the RMs are being used, i.e. the immediate and active control of the results being reported from an analytical run or event, and an objective, retrospective assessment of the quality of those results. 

Advantages of intermittent extraction are similar to those of solid-fluid-vortex extraction. A disadvantage is caking of the polymer in the case of a high polymer concentration in the extract or by loss of extraction fluid. Interlaboratory comparison is restricted. 

HPLC-QFAAS is also problematical. Most development of atomic plasma emission in HPLC detection has been with the ICP and to some extent the DCP, in contrast with the dominance of the microwave-induced plasmas as element-selective GC detectors. An integrated GC-MIP system has been introduced commercially. Significant polymer/additive analysis applications are not abundant for GC and SFC hyphenations. Wider adoption of plasma spectral chromatographic detection for trace analysis and elemental speciation will depend on the introduction of standardised commercial instrumentation to permit interlaboratory comparison of data and the development of standard methods of analysis which can be widely used. 

As to the analysis of trace elements in paper, cardboard and raw materials for the production of paper, high concentration elements such as Cu, Fe or Ti can easily be determined by FAAS Cd and Pb are frequently analysed by GFAAS. Cadmium in pulp and paper was determined by AAS after pressurised digestion with nitric acid [145]. An interlaboratory comparison of Cd in wrapping paper was reported, mainly based on pressure digestion in FIFE bombs with sub-boiled nitric acid, followed by ETAAS [59]. For wrapping paper used for foodstuffs, next to the total content of toxic heavy metals, the soluble or leachable fraction is of particular interest. 

Taking into account that Eqs. (3.16) may also contain some unknown influences Uk which reveal themselves in interlaboratory comparisons but may normally be hidden in the term eA>, the fundamental signal model is given by... 

Danzer K, Wank U, Wienke D (1991) An expert system for the evaluation and interpretation of interlaboratory comparisons. Chemom Intell Lab Syst 12 69... 

The Kerridge-Bongard model of information is of great importance in quality assurance, in particular for the assessment of interlaboratory studies. Examples of the information-theoretical evaluation of analytical results within the context of interlaboratory comparisons have been given by Danzer et al. [1987, 2001], Wienke et al. [1991] and Danzer [1993]. 

Valkirs et al. [105] have conducted an interlaboratory comparison or determinations of di- and tributyltin species in marine and estuarine waters using two methods, namely hydride generation with atomic absorption detection and gas chromatography with flame photometric detection. Good agreement was obtained between the results of the two methods. Studies on the effect of storing frozen samples prior to analysis showed that samples could be stored in polycarbonate containers at - 20 °C for 2 - 3 months without significant loss of tributyltin. 

Three years interlaboratory comparison studies of the BL bacteria test 189... 

IMEP 9, Trace Elements in Water III, Cd, Certified Range 81.0-85.4 nmol l-1 , European Commission, Joint Research Centre, Institute for Reference Materials and Measurements (EC-JRC-IRMM), Geel, Belgium (1998). [www.irmm.jrc.be/html/interlaboratory comparisons/imep/ index.htm] (accessed 30 November, 2006). 

This chapter has considered two of the types of interlaboratory comparison exercise in which your laboratory may participate. It is important to remember that proficiency testing schemes and collaborative studies have different aims. The former is a test of the performance of the laboratory, whereas the latter is used to evaluate the performance of a particular analytical method. Laboratories should participate in proficiency testing schemes (where an appropriate scheme is available) as this provides an independent check of the laboratory s performance. This chapter has described the key features of proficiency testing schemes and explained how the results from participation in a scheme should be interpreted. 

Proficiency Testing by Interlaboratory Comparisons - Part 1 Development and Operation of Proficiency Testing Schemes , ISO/IEC Guide 43-1 1997, International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC), Geneva, Switzerland, 1997. 

Participation in Proficiency Testing (PT) schemes/interlaboratory comparisons and review of data... 

In addition, a system for making sure staff are appropriately qualified and trained for the work that they are doing must be in place. This will enable an auditor to see clearly the demonstrated competence of the staff and how this has been checked. The requirements for all major items of equipment must be listed, to ensure that the equipment in use is suitable for the task, is in working condition and, where necessary, is calibrated. For all of the instrumentation there needs to be a documented schedule for maintenance. Measurements must be traceable, that is, the laboratory must be able to show how the calibration of measurement instruments is traceable to National or International Standards. Where this presents practical problems, as in some chemical measurements for example, interlaboratory comparison and the use of reference materials (and preferably Certified Reference Materials) will be required. 

Where appropriate, performance in proficiency testing schemes and/or interlaboratory comparisons is satisfactory and has not highlighted any problems or potential problems. Where performance has been unsatisfactory, corrective action has been taken. 

Proficiency Testing Determination of laboratory testing performance by means of interlaboratory comparisons. 

Furuta, N. (1991). Interlaboratory comparison study on lead isotope ratios determined by inductively coupled plasma mass spectrometry. Analytical Sciences 7 823-826. 

Whittle [29] has described a thin-layer chromatographic method for the identification of hydrocarbon marker dyes in oil polluted waters. McLeod et al. [25] conducted interlaboratory comparisons of methods for determining traces of aliphatic and aromatic hydrocarbons in marine sediments. Agreement within a factor of 2 to 3 was obtained between the 12 participating laboratories. 

In an interlaboratory comparison of metal determinations in soils the element boron is mentioned [7]. 

Are they traceable For example, to CRM, a reference method, interlaboratory comparison, or other. 

Quality control, however, needs more attention. For example, it has been reported that much of the chemical data produced by the International Indian Ocean Expedition is unusable because of doubts about its accuracy. Such reports are a perennial source of confusion in marine chemistry. Better calibration, universal standards, and interlaboratory comparison are essential if we are to continue our present field methods, in which independent investigators make measurements that are presumably comparable (NRC, 1971, pp. 54-55). 

The need for oceanographic standards and interlaboratory comparisons was again reiterated more than 20 years later in the 1993 report of the Ocean Studies Board Committee on Oceanic Carbon ... 

Stichler, W. 1995. Interlaboratory comparison of new materials for carbon and oxygen isotope ratio measurements. Pp. 67-74 in Reference and Intercomparison Materials for Stable Isotopes of Light Elements, Vienna International Atomic Energy Agency, LAEA-TECDOC-825. 

PAMPA can quickly provide information about passive-transport permeability that is not complicated by other mechanisms (e.g., active transport, paracel-lular transport, and metabolism) [103], The procedure is used increasingly in pharmaceutical research in major pharmaceutical companies as well as in CROs [13, 137, 175, 179, 165, 119, 70], However, it should be stated that PAMPA to date comprises numerous methods applied in various laboratories using different membrane constituents, sink conditions, permeation times, etc., which makes interlaboratory comparison extremely difficult. Therefore, standardization and validation methods of this technique should be introduced. 

Detecting Inconsistent Subsamples Only. A positive response to this choice results from an analytical problem involving an interlaboratory comparison. The main interest is to find those laboratories which produce inconsistent results. The results of each... 

The primary factor which governs the detection limit, the uncertainty of the blank, can differ markedly depending upon whether it is estimated from a model (intercept, baseline), or from a direct observation, or from "blind" interlaboratory comparison. Inappropriate blank evaluation, together with inadequate reporting of data when at or below the detection limit are seen as two of the most critical sources of information loss or information distortion, with serious potential effects in environmental and regulatory areas (3 ). 

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