Ph-Value With Tablet - Lovibond MiniDirect Mode D'emploi

Methods
GB
0.0.0
Zero
Test
PH
RESULT
Notes:
1 . For photometric determination of pH-values only use PHENOL RED tablets in black
printed foil pack and marked with PHOTOMETER .
2 . Water samples with low values of Alkalinity-m (below 35 mg/l CaCO
pH readings .
3 . pH-values below 6 .5 and above 8 .4 can produce results inside the measuring range .
A plausibility test (pH-meter) is recommended .
4 . The accuracy of the colorimetric determination of pH-values depends on various
boundary conditions (buffer capacity of the sample, salt contents etc .) .
5 . Salt error
Correction of test results (average values) for samples with salt contents of:
Indicator
Phenol red
The values of Parson and Douglas (1926) are based on the use of Clark and Lubs
buffers . 1 Mol NaCl = 58 .4 g/l = 5 .8 %
MiniDirect_ClpH_1 09/2008

pH-value with Tablet

6.5 – 8.4
Fill a clean vial (24 mm Ø) with 10 ml of the water sample and
perform zero calibration (see "Operation") .
Add one PHENOL RED PHOTOMETER tablet straight from the foil
to the 10 ml water sample and crush the tablet using a clean stirring
rod .
Close the vial tightly with the cap and swirl gently several times until
the tablet is dissolved .
Place the vial in the sample chamber making sure that the
are aligned .
Press the [ZERO/TEST] key .
The method symbol flashes for approx . 3 seconds .
The result is shown in the display as pH-value .
Tolerance: ± 0,1 pH
Salt contents
1 molar
– 0 .21
2 molar 3 molar
– 0 .26 – 0 .29
marks
) may give wrong
3
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