Improvement schemes

Improvement schemes can be defined as a succession of individual interlabora-tory studies in which several laboratories analyse the same test samples for the same characteristics (usually the content of an analyte), following a similar protocol to validate each individual step of their own analytical method in order to eliminate all sources of systematic errors [47]. 

An important aspect of QA is related to the participation of laboratories in collaborative projects which enables them to check the performance of methods and to share expertise with colleagues working in similar fields. In this respect, improvement schemes are particularly well suited and were successfully used for evaluating and improving the state-of-the-art of speciation studies in Europe (Quevauviller, 1998b). 

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An improved version, called COSMO for realistic solvents (COSMO-RS), has also been created. This method has an improved scheme for modeling nonelectrostatic effects. It can be adapted for modeling the behavior of molecules in any solvent and, gives increased accuracy of results as compared to COSMO. 

Synthetic rubber latex was made by a process with a large and hazardous inventory of butadiene and styrene. In a modified process, the reactor has an initial charge of water and emulsifier. Also, the monomers are added to the reactor as one premixed stream and the emulsified aqueous sodium persulfate is added as the other stream. The improved scheme, discussed by Englund (1991a) contains less hazardous material and at a lower, more controllable temperature. It illustrates that large and established processes may be made safer by applying inherent safety. 

The following list, while not exhaustive, identifies many of the issues which will need careful consideration. In many instances it might be necessary to seek the advice of a specialist traffic consultant, either in the design of a scheme or in access, or to negotiate with the highway authority the impact of a proposed development and any attendant road-improvement schemes. 

With the above information in hand, it is then possible to consider different improvement schemes. 

Can you do better There is no need to calculate volumes and flow rates. Just come up with an improved scheme. 

Improvement schemes Validation of new or improved methods by comparison with fully validated method Less costly exercise than full validation... 

Improvement schemes can be defined as a succession of individual interlaboratory studies in which several laboratories analyse the same test samples for the same characteristics (usually the content of an analyte), following a similar protocol to validate each individual step of their own analytical method (Quevauviller, 1999a). They enable laboratories to develop and validate all steps of new or existing analytical procedure(s) in adequately organised successive exercises which may be considered as preliminary studies for laboratory or method performance studies or certification of RMs (Griepink and Stoeppler, 1992 Quevauviller, 1998b). Such programmes are particularly valuable in the case of speciation studies since the analytical procedures include several complex and critical steps. 

The objective of improvement schemes is to study and validate each step of different analytical procedures applied by different laboratories in a collaborative manner. Such programmes usually involve groups of 20-50 laboratories. In the best case, each critical step of the procedure should be evaluated in an adapted exercise. The individual steps may be studied with a series of different materials in a stepwise manner. In principle the strategy consists of starting from the simplest matrix, e.g. pure solutions and/or mixtures of compounds in solution, for testing the performance of the detector. The analysis of more complex matrices (e.g. raw extract, purified extract) enables the separation and/or clean-up steps to be tested, whereas solid samples are used to test the entire procedure. Spiked samples can be analysed to evaluate the extraction procedure, within the limits of this evaluation (as commented in Section 2.3.1). Such an approach is actually similar to the steps that should be followed when developing and validating a new method in a laboratory. 

Lagarde, L., Amran, M., Leroy, M., Demesmay, C., Olle, M., Lamotte, A., Muntau, H., Michel, R, Thomas, R, Caroli, S., Larsen, E., Bonner, P., Rauret, G., Foulkes, M., Howard, A., Griepink, B. and Maier, E. (1999a) Improvement scheme for the determination of arsenic species in mussel and fish tissues. Fresenius J. Anal. Chem., 363(1), 5. 

Lagarde, F., M.B. Amran, M.J.F. Feroy, etal. 1999. Improvement scheme for the determination of arsenic species in mussel and fish tissues. Fresenius J. Anal. Chem. 363 5—11. 

A new catalytic system has been found - simply mixing [Rh(COD)Cl]2 and chiral bidentate ligands (BINAP or TunePhos) in situ led to a significant improvement (Scheme 6) [38-41], The non-coordinate solvent 1,2-dichloroethane and the counter-ion SbFroom temperature with the [Rh(BINAP)Cl]2 precatalyst, whereas the in situ [Rh(COD)Cl]2/BINAP system is very efficient and achieved... 

Develop cost-effective schedule improving schemes. 

J. L. Sandlin and Y. Ito, Large-scale preparative countercurrent chromatography with a coil planet centrifuge,/. Liquid Chromatogr. 5(12) 2153-2171 (1985). Y. Ito and R. Bhatnagar, Improved scheme for preparative CCC with a rotating coil assembly, /. Chromatogr. 207 171-180 (1981). 

Recently, the conditions for the hydride reduction of the C-l ketone were improved (Scheme 27). Treating 1 or herkinorin (170, for synthetic conditions see Scheme 8) with an aqueous solution of sodium borohydride in THF selectively reduced the C-l ketone (171 and 172) in 77 or 45% yield respectively, with no evidence of C-8 epimerization [62]. Treatment of la-hydroxysalvinorin A (171)... 

This paper is organized as follows. In Section 2 we outline Ninomiya s algorithm. In Section 3 the sequence of RMS formulas is reviewed. In Section 4 we show how to incorporate the FLR method into the Ninomiya scheme to construct an improved scheme. In Section 5 the present algorithm is outlined. Section 6 demonstrates the performance of the present routine by using various test problems. 

In view of the urgent need for the improvement of the quality of the analyses, a project for MeHg has been discussed and designed with a group of experts in the frame of the BCR-Programme. The programme of work was set up in the form of an improvement scheme (see Chapter 12). In particular, the various steps of the analytical methods were studied individually by each of the participants e.g. extraction, clean-up and separation. This improvement scheme is fully described in Chapter 12 the present section gives a summary of this certification of tuna fish, which followed the interlaboratory studies. 

The overall program started by a circulation of a questionnaire sent to each participant, related to their current QA practices. The responses allowed to evaluate the areas of need and to adapt the improvement schemes [54]. Workshops and seminars were considered to be an important part of the improvement programme since they enabled participants to share expertise and to receive pragmatic and clear advice on how to solve their possible problems. 

The improvement schemes, usually involving a group of 20 to 50 laboratories, may start with a simple exercise, e.g. by distributing solutions or pure substances. This enables to evaluate the methods of final detection and to possibly optimise them. More complex samples, e.g. complex mixtures of compounds including interferents or extracts, are therefore analysed and the pretreatment/separation steps are assessed at this stage, the performance of the method is re-evaluated and the procedure may be fully reconsidered if necessary. An intermediate step can be the analysis of a spiked sample, which is followed by real samples. The outcome of the different exercises is discussed... 

Various examples of improvement schemes organised by the BCR prior to certification campaigns are summarised elsewhere [5] and briefly mentioned in various chapters of this book, e.g. for PCBs and PAHs, organotins, microbiological measurements, etc. The following section describes in detail some of them. 

Example of improvement scheme Methyl mercury in environmental matrices... 

RESULTS OF THE THREE INTERCOMPARISONS INCLUDED IN THE IMPROVEMENT SCHEME ON MeHg IN FISH TISSUES... 

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