Tintometer Lovibond MD 110 AL 110 Mode D'emploi page 39

Methods
GB
PH
0.0.0
Zero
Test
PH
RESULT
Notes:
1. When testing chlorinated water the residual chlorine contents can influence the colour
reaction of the liquid reagent. This can be avoided (without interfering with the pH
measurement) by adding a small crystal of Sodiumthiosulfate (Na
sample before adding the PHENOL RED solution. PHENOL RED tablets already contain
Thiosulfate.
2. Due to differing drop sizes results can show a discrepancy in accuracy by comparison
with tablets. This can be minimised by using a pipette (0.18 ml PHENOL RED solution is
equivalent to 6 drops).
3. After use replace the bottle cap securely.
4. Store the reagent in a cool, dry place ideally between 6°C and 10 °C.
5. Salt error
For higher salt concentrations the measurement values have to be adjusted as follows:
Salt content
Correction
according to Kolthoff (1922)
1)
according to Parson und Douglas (1926)
2)
Reagent
PHENOL RED solution
MD110_3a 03/2020
pH-value with liquid reagent
6.5 – 8.4
Fill a clean vial (24 mm Ø) with 10 ml of the water sample and
perform zero calibration (see "Operation").
Fill the vial with drops of the same size by holding the bottle vertically
and squeeze slowly:
6 drops of PHENOL RED solution.
Close the vial tightly with the cap and invert several times to mix the
contents.
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: ± 0.2 pH
30 g/l (seawater)
- 0,15
1)
Form of reagent/Quantity
Liquid reagent / 15 ml
S O · 5 H
2 2 3
60 g/l 120 g/l
- 0,21 - 0,26
2) 2)
Order-No.
471040
marks
O) to the
2
180 g/l
- 0,29
2)
39