Hach Ultra POLYMETRON 9210, Operator'S Manual

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Page 24
SILKOSTAT 9210
Reagent 2 - Oxalic reagent
Oxalic acid dihydrate, C
2
H
2
O
4
.2H
2
O, >99.5%, neat (analytical quality),
(FLUKA# 75700, MERCK# 100495 or equivalent)
80 g
1) Fill a 2-litre graduated flask to 2/3rds capacity with demineralised water (with the lowest
possible silica content). Add the oxalic acid whilst stirring the solution.
2) Keep stirring until completely dissolved (<5minutes).
3) Make up the volume to the gauge line (2 litres).
4) Transfer to the 2-litre container provided for this reagent.
Reagent 3 - Reducing reagent
Concentrated sulphuric acid, H
2
SO
4
, 95-97%, neat (analytical quality)
(FLUKA# 84721, MERCK# 100731 or equivalent)
25 mL
Mohr's Salt = Ferrous ( II ) ammonium sulphate hexahydrate,
(NH
4
)
2
Fe(SO
4
)
2
,6H
2
O, >99%, neat (analytical quality)
(FLUKA# 09720, MERCK# 103792 or equivalent)
40 g
1) Fill a 2-litre graduated flask to 2/3rds capacity with demineralised water (with the lowest
possible silica content). Add the concentrated sulphuric acid whilst stirring the solution
(measured out from a test tube).
2) Still stirring, add the ferrous ammonium sulphate hexahydrate.
3) Keep stirring until completely dissolved (<5minutes).
4) Make up the volume to the gauge line (2 litres).
5) Leave to cool before transferring to the 2-litre container provided for this reagent.
Calibration solution
CONCENTRATED SOLUTION
Use of Titrisol

(Merck) cartridge
Dillute one cartridge of Titrisol

Merck 109947 solution into one litre of demineralised water
will give a concentration of 1000 mg/litre of Si , ie, 2139 mg/litre of SiO
2
.
Dillute this solution, 100 times, ie, 10 ml in one litre. This will give a concentration of
10 mg/litre of
Si, ie, 21.39 mg/litre SiO
2
.