Batch analysers with final transfer

Automatic centrifugal analysers are also batch analysers with final transfer of the reaction mixture prior to measurement. They have become very popular in clinical laboratories in the last few years. The different manufacturers offer a wide a range of models the Centrifichem Models 400 and 600, manufactured by Union Carbide, are probably the best known and most widely used, so they will be described here as the most typical representatives. It should be noted, though, that there are no significant differences between 

Centrifugal analysers consist of two separate instrumental units the dosing module, which dispenses samples and reagents, and the analyser module, where samples and reagents are mixed and the reaction mixture is measured, generally spectrophotometrically. The most advanced models feature a computer that controls the operation of the two units and allows the user to program the system for the determination of a given number of parameters and delivery of printed results. 

As all 30 samples are, apparently, measured in a simultaneous fashion, the system can be said to effect a parallel multi-determination —hence the generic name parallel fast analyser given by some workers to these instruments, which are even dealt with separately from batch analysers in automatic methods of analysis. However, such a difference is only apparent and, in fact, it is a typically discontinuous process, both because of the sequential measurement (with a single detector) and because there is a manual intermediate operation (the transport of the transfer disc from one module to the other). 

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A typical example of batch analyser without final transfer using ordinary cuvettes is the Technicon Model RA-1000. As can be seen from Fig. 8.10, it consists of a central unit with 100 disposable cuvettes receiving samples and reagents from two additional trays. A computer controls all the instrument functions, acquires data and presents the final results once processed. This analyser is suitable for both kinetic and end-point measurements and can perform emergency analyses without significantly altering Its functioning. 

The work is organized in two parts in the first part kinetics is presented focusing on the reaction rates, the influence of different variables and the determination of specific rate parameters for different reactions both homogeneous and heterogeneous. This section is complemented with the classical kinetic theory and in particular with many examples and exercises. The second part introduces students to the distinction between ideal and non-ideal reactors and presents the basic equations of batch and continuous ideal reactors, as well as specih c isothermal and non-isothermal systems. The main emphasis however is on both qualitative and quantitative interpretation by comparing and combining reactors with and without diffusion and mass transfer effects, complemented with several examples and exercises. Finally, non-ideal and multiphase systems are presented, as well as specific topics of biomass thermal processes and heterogeneous reactor analyses. The work closes with a unique section on the application of theory in laboratory practice with kinetic and reactor experiments. 

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