387 / 670
(e)
Zinc acetate dihydrate
Zn(CH
3
COO)
2
· 2H
2
O
,
—
ACS reagent puriss p.a., ≥ 99.0 %. Sigma
58
Aldrich # 96459 or equivalent
59
(f)
Nitric acid (HNO3).
—
Minimum 65% p.a., Merck #100452, or equivalent
60
(g)
Standardized AgNO3 solution,
0.1 mol/l (0.1 N)
Titripur® Reag. Ph Eur,Reag. USP, #
61
1.09081.1000 or EM3214-1; or ready-to-use
standardized titrant prepared according to
62
GB/T 601, or
equivalent.
63
(h)
Sodium Chloride (
NaCl) standardized solution), 0.1 M
.
—
Alfa Aesar, # 35616, (Ward Hill,
64
MA, USA), or equivalent.
65
(i)
Glacial acetic acid, 100%.
—
anhydrous for analysis EMSURE® ACS, ISO, Reag. Ph
66
Eur
MERCK, #
100063
or equivalent
67
(j)
Potassium nitrate, (KNO3).
—
for analysis EMSURE® ISO,Reag. Ph EurMERCK, # 105063
68
or equivalent.
69
(k)
Acetone
.
—
for cleaning of the electrode.
Honeywell, # 010-4, (Muskegon, MI, USA) or
70
equivalent.
71
(l
) Dimethylpolysiloxane.
—
defoaming agent. Sigma-Aldrich, #DMPS2C or equivalent.
72
D. Preparation of solutions
73
(
a
)
Standardized AgNO
3
solution, 0.1 M.
—
If ready-to-use AgNO
3
standard solution (Cc) is not
74
available, then weigh 16.9890 ± 0.0005 g AgNO
3
previously dried for 2 h at 120 ± 2°C. Dissolve
75
in water and make up to the mark in a 1000 mL volumetric flask. Store in a brown reagent bottle.
76
Note 1: After preparation, check the titer by titration of 5.0 mL with exactly 0.1 M NaCl solution.
77
For either commercial or in-house solution verify the titer on a regular basis.
78
Note 2: The standardized AgNO
3
solution must be protected from light, and can be stored for up
79
to 2 months.
80
(
b
)
Sodium chloride solution, 0.1 M
.
—
If ready-to-use NaCl standard solution is not available,
81
weigh 5.8440 ± 0.0005 g NaCl (
C
b), previously dried for 2 h at 110 ± 2°C. Dissolve in water and
82
make up to the mark in a 1000 mL volumetric flask.
83
Note: This solution is stable for up to 1 month.
84
(c)
Precipitating solution (Carrez) I
.
—
Weigh 106 g potassium ferrocyanide trihydrate, (
C
d)
85
dissolve in an appropriate amount of water and transfer into a 1000 mL volumetric flask.
86
Makeup to the mark using water. Mix well.
87
(
d
) Precipitating solution (Carrez) II.
—
Weigh 220 g zinc acetate dihydrate (
C
e) and transfer into
88
a 1000 mL volumetric flask. Dissolve with an appropriate amount of water, and add 30mL
89
glacial acetic acid. Make up to the mark using water. Mix well.
90
(
e
)
Nitric acid solution
.
—
With care, add 100 mL concentrated nitric acid (
C
f) to 300 mL water.
91
Mix well.
92
(
f
)
Wash solution
.
—
According to autosampler/titrator manufacturer’s instructions.
(e.g.
93
Acetone, Nitric acid solution
[
D
e]
, or other)
94
2015.07/2015.08 (February 2016)
Chlor-02/Chlor-04
FOR ERP USE ONLY
DO NOT DISTRIBUTE