CHAPTER 5 AUTO mode and time files
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C H A P T E R 5
AUTO mode and time files
Introduction
The AUTO mode of the DECADE enables a time-based, automated and full
parametric control of electrochemical detection (ECD). This is particularly
useful when during a run or between runs settings have to be changed such
as the sensitivity, auto zero or control of external equipment (i.e. trigger to
start integration software etc.). A Time file contains a series of data lines in
which the settings of the DECADE can be changed with 1 second time
resolution. A time file is executed only in the AUTO mode.
Fig. 9. Programming a time file using the '(AUTO) PRGR' screen.
The file is made using the ‘(AUTO) PRGR’ screen on the DECADE (Fig. 9) or,
when the DECADE is equipped with the RS232 option, by using the time file
editor in ‘DECADE Dialogue for Windows’. Programmable parameters
comprise cell potential, range, auto zero, offset, rise time, electrically actuated
injector (if present) and the DECADE output contacts to control the status of
external equipment.
Range programming
In certain analyses large differences in analyte concentration (and peak
height) occur. If the analyte with the highest concentration is on scale, another
analyte may be recorded at a low output resolution. When the small peak is
magnified with integration software a typical stepwise peak profile is seen
(Fig. 7). In such a case a chromatogram can be obtained using a time file to
switch the sensitivity of the controller to another range during the run (Fig. 10).
In Table VI an example is given of a time file for sensitivity switching between
2 peaks. In this example the system is equipped with an electric valve, which
means that programming the switching of the valve is possible (Fig. 9,
‘Actor’). At time 00:00 the valve is switched to ‘inject’, the trigger to start the
integrator is connected to the ‘INJECT MARKER’. At time 00:10 the valve is
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