On-line estimation and adaptive control of bioreactors - Process measurement and control 1 : G. Bastin and D. Dochain

the development of mixture designs and retention mapping and their general application to opti-misation problems. It is interesting to compare a later paper (Coenegracht et al.) which explores the use of multicriteria decision-making methods with various retention mapping procedures based on different approaches varying mobile phase composition. The next four papers describe the theory and utilisation of the DryLab simulation software for both gradient and isocratic separations (Snyder), a more theoretical approach to gradient optimisa-tion (Jandera) and the computer simulation of isocratic and gradient ion-exchange separations. The DryLab simulation software appears in many other articles in this book; for example in the opti-misation of a separation of pharmaceuticals (Lankmayr et al.), in a comparison with LCSIM (Schmidt) for the optimisation of a gradient separation of OPA-amino acids, in the optimisation of a herbicide mix (Lehman et al.), and for separating intermedi-ates of a leukotriene inhibitor. There are other papers discussing computer simulation such as the Pro-Digest-LC (Massart et al.) for peptide separations, and the MY-CASYST system (Jinno et al.) which perhaps bridges simulation approaches and expert systems. Expert systems are now becoming available as genuinely useful tools for chromatographers and a dozen or so papers attest to their value. The European Community ESPERIT programme supported an extensive system development, the modules for system optimisation (Schoenmakers et al.) and the elegant module to 201 aid in method validation (Mulhol-land et al.) are well described in the respective papers. Other highlights from this section are descriptions of the LABEL system (Massart et al.) for the selection of the optimum method for determining the label claim of pharmaceutical products, the major development effort devoted to ECAT (Expert Chromatographic Assistance Team), the trouble-shooting system of Tsuji et al., Cathie, a gas chromatographic system (Milne), and HPLC-METABOLEXPERT (Valko et al.) which predicts metabolite retention time in HPLC. Successful utilisation of computer methods requires an ability to determine specific information about separations such as what constitutes an optimum separation or how peaks move relative to each other during optimisation process (peak tracking). Two approaches to peak tracking are described , one based on 'fuzzy' theory (Lankmayr et al.) and a simpler, area-based method (Mol-narl. Objective, or optimisation, functions continue to be hotly debated and the paper by Cela et al. presents a well-balanced assessment of the main approaches. Finally there are, interspersed throughout the book, a small number of application papers. It would appear that only …