4 ph calibration – Metrohm 794 Basic Titrino User Manual

Page 21

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2.4

Tutorial

794 Basic Titrino

17

2.4.4 pH calibration

pH calibrations are not a requirement for pH titrations, when the equivalence point is de-

termined from a curve. For end-point titrations, however, where titration is performed to a

fixed, specified pH value, a calibration should be performed.

Selection of the calibration mode, CAL

<MODE>

<ENTER>

• Press <MODE> repeatedly until "CAL" appears in

the display and confirm the mode with <ENTER>.

The instrument is ready for a 2-point calibration. The

second display line shows the current calibration data

for measuring input 1.

Calibration procedure

<START>

<ENTER>

<ENTER>

<ENTER>

oder

<STOP>

• Immerse your electrode in the first buffer and start

the calibration procedure.

Inquiry of calibration temperature.
• Enter the current temperature. If you have a tem-

perature sensor connected, this inquiry is skipped.

pH value of the first buffer.
• Enter the pH value of the buffer at your calibration

temperature.

The voltage of the first buffer is measured. When the

measured value has met the set drift criterion, the

measurement is stopped and the pH value of the sec-

ond buffer is requested.


• Now enter the pH value of the second buffer. If you

require a 1-point calibration, you can also terminate

the calibration with <STOP>.

At the end of the calibration, the calibration data ob-

tained are displayed: asymmetry pH and slope.

The calibration data can be viewed at any time under the <CAL.DATA> key. Our calibra-

tion data are stored under ">input 1".

The calibration report can be printed out at any time with the key sequence:

<PRINT><CAL.DATA><ENTER>

mode

mode CAL

CAL ********

pH(as) 7.00 slope

1.000

CAL

cal.temp. 25.0°C

25.0°C

buffer 1 pH

7.00

25.0°C

buffer 2 pH

4.00

CAL ********

pH(as) 6.89 slope

0.985

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