Metrohm 794 Basic Titrino - Manual (Page 22)

2.4. Tutorial
794 Basic Titrino
18
2.4.5 Statistics, acid capacity of drinking water
Let us now determine the acid capacity of drinking water. For this, the SET (set endpoint
titration) mode is used to titrate to pH = 4.3.
First select the mode SET pH (keys <MODE> and <SELECT>).
Now set the end point.
Entry of the end point and the control parameters
<PARAM>
<ENTER>
<ENTER>
<ENTER>
<ENTER>
2 × <QUIT>
• Press <PARAM>. The display shows:
Control parameters for EP1
• Set the end point to pH = 4.3.
• Dynamics means the control range in which the
adding of the titrant is controlled in dependence on
the measured value (OFF: largest control range, i.e.
slow titration).
With buffered systems such as drinking water, this
value can be set lower, e.g. to 3. I.e. 3 pH units be-
fore the set EP controlled dosing starts.
Maximum possible titration rate inside the control
range.
Minimum titration rate inside the control range.
• Quit the inquiry with <QUIT>.
Mount an Exchange Unit with c(HCl) = 0.1 mol/L as titrant. Add 25 mL drinking water as
sample and start the titration with <START>. During the titration the first line of the dis-
play shows the measured value and dispensed volume. The "c" in pHc shows that the
electrode assembly has been calibrated. The second line shows a "control bar", which
indicates the control deviation of the current measured value from the set end point.
parameters
>SET1
>SET1
EP at pH OFF
>SET1
EP at pH 4.3
>SET1
dynamics OFF
>SET1
dynamics 3
>SET1
max.rate 10.0 ml/min
>SET1
min.rate 25.0µl/min
pHc 6.34 0.426 ml
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