Preparation instructions for P 700 IQ-solutions
7
2
Preparation instructions for standard solutions ST 0.0, ST 1.6, ST 8.0, ST 20.0
These are preparation instructions for standard solutions that are needed for operating the P
700 IQ Orthophosphate Analyzer:
WTW article no.
Standard solution
Concentration
821 971
ST0.0
0.0 mg/l PO4-P
821 997
ST1.6
1.6 mg/l PO4-P
821 996
ST8.0
8.0 mg/l PO4-P
821 995
ST20.0
20.0 mg/l PO4-P
Composition
ST0.0
KH
2
PO
4
(0.0 mg/L PO4-P)
HCl (0.05 %)
Demineralized water
ST1.6
KH
2
PO
4
(1.6 mg/L PO4-P)
ST8.0
KH
2
PO
4
(8.0 mg/L PO4-P)
ST20.0
KH
2
PO
4
(20.0 mg/L PO4-P)
Chemicals required:
•
Potassium dihydrogen phosphate (KH
2
PO
4
) p. A.; M = 136.09 g/mol
•
fuming hydrochloric acid (HCl) 37 % p. A. (
≈
12 M)
•
Demineralized water (H
2
O); Residual conductivity
25 °C
κ < 2µS/cm
Containers, labels:
•
Rectangular bottle 1000 ml (HDPE) as per Chapter 5.1
•
Closure for 1000 ml bottle (HDPE) as per Chapter 5.1
•
Labels with color marking as per Chapter 5.2
Aids and appliances:
•
Drying cupboard (min. 120 °C)
•
Analytical balance (
±
0.1 mg)
•
Precision balance (
±
0.1 g) with summing function
•
Reactor with agitator
•
Measuring beaker 5 L
•
Funnel
•
Measuring cylinder 100 mL
•
Beaker 50 mL
•
pH indicator rods (e.g. pH 0…6)
Preparations
•
Check reactors, agitators, vessels and other aids and appliances mentioned above for
cleanliness, clean if necessary.
•
Approx. Dry approx. 1 g of KH
2
PO
4
in the drying cupboard at 120 °C for at least 2 h and
then bring to room temperature in the desiccator (does not apply for ST 0.0).
•
Fill the measuring beaker with demineralized water and then empty again. Tare the still
wet measuring beaker using the precision balance.
•
Insert the funnel in the filler neck.
Production
•
Fill the measuring beaker with demineralized water and place on the precision balance.
The mass of the water poured in is saved by pressing the sum button.
•
Pour the contents of the measuring beaker through the funnel into the reactor. Repeat
this process until the approximate amount of water (see Table 2-1) is in the reactor.
•
Depending on the initial solution quantity (see Table 2-1), weigh the corresponding
amount of KH
2
PO
4
into the 50 mL beaker with the analysis balance. This amount is
transferred with the next weighed measuring beaker quantitatively into the reactor. Make
