Figure 13.6
Simplified block diagram of a microprocessor-controlled potentiometric titrator.Sets of parameters such as burette volume, reagent strength, increment size and time interval, end-point
potential, format of results, etc., can be stored and recalled from memory as standard methods for
routine analyses. An alphanumeric keyboard is used to enter or change the parameters, to take
individual pX or mV readings and to control the rinsing and the refilling of the automatic burette. Raw
titration data and computed analytical results can be printed out as a permanent record, and titration
curves can be produced on a chart recorder or VDU.
New methods can be created by automatic optimization of parameters during a 'trial run' and all
methods can be stored permanently in a non-volatile area of memory which is preserved even when the
instrument is switched off. Some instruments provide a means of producing first and second derivatives
of the titration curve (p. 243) which can be advantageous where the end-point is indistinct or there is
more than one end-point to be detected. Titrators with a substantial amount of RAM incorporate what is
in effect a dedicated microcomputer.
Accessories are available for some instruments to enable photometric or voltammetric titrations (e.g. the
Karl–Fischer determination of water) to be performed. Others allow the direct transfer of weighings
from an electronic balance into RAM where they can be used in the computation of results.