Lovibond Tintometer MD100 Instrucciones página 31

Methods
GB
Notes:
1. Close the vials with the cap immediately after adding the VARIO Molybdate 3 reagent
solution, otherwise low readings may result.
2. The given reaction time of 4 minutes refers to a water sample temperature of 20 °C.
At 30 °C a reaction time of 2 minutes, at 10°C a reaction time of 8 minutes are required.
3. The given reaction time of 1 minute refers to a water sample temperature of 20°C.
At 30 °C a reaction time of 30 seconds, at 10 °C a reaction time of 2 minutes are
required.
4. Interferences:
Substance
Iron
Phosphate
Sulfide
Occasionally water samples contain forms of silica which reacts very slowly with
Molybdate. The nature of these forms is not known.
A pre-treatment with Sodium hydrogencarbonate and then with Sulfuric Acid will make
these forms reactive to Molybdate (pre-treatment is given in "Standard Methods for the
Examination of Water and Wastewater" under " Silica Digestion with Sodium Bicarbo-
nate").
5. Due to differing drop size results can show a discrepancy in accuracy by comparison
with the mentioned tolerance. This can be minimised by using a pipette (14 drops is
equivalent to 0.5 ml).
6. Conversion:
mg/l Si = mg/l SiO
2
Reagent
Set
VARIO LR Silica Amino Acid F10
VARIO Silica Citric Acid F10
VARIO Molybdate 3
MD100_8 07/2016
Interference
large amounts interfere
does not interfere at concentrations less than 50 mg/l PO
at 60 mg/l PO the interference is approx. – 2 %
4
at 75 mg/l PO the interference is approx. – 11 %
4
interferes at all levels
· 0.47
Form of reagent/Quantity
Powder Pack / 100
Powder Pack / 200
Liquid reagent / 2x 50 ml
4
Order-No.
535690
31