HIRANUMA APPLICATION DATA

Data No.

Automatic Titrator

G2Apr. 5,
2019

Determination of trace chloride ion incopper sulfate solution

Metals
1. Abstract

This report introduces an example of the determination of trace chloride ion in the solution containing
highly concentrated copper sulfate.
The precipitation titration with silver nitrate standard solution is generally used for the determination ofchloride ion in copper sulfate solution. The endpoint of the titration is detected with indicator method or thepotentiometric method. The potentiometric method is used for this sample because the color change ofindicator reagent is obscure in this sample containing highly concentrated copper sulfate. However, it tends toshow the difficulty to detect the endpoint because of the less sensitivity of electrode under highly concentrated
copper sulfate. Therefore the potentiometric titration is performed with the specially treated silver electrode
that the silver chloride is coated.

Cl-＋AgNO3→

AgCl＋NO3-

2. Configuration of instruments and reagents(1) Configuration of instruments
Main unit: Hiranuma Automatic Titrator

COM SeriesElectrode: Silver electrodeAG-311A (Silver chloride-coated electrode)

Reference electrodeMS-231Z*The following electrodes are also usable.
・AGR-801AZ (Silver chloride-coated silver reference combination electrode)・AGR-811AZ (Silver chloride-coated silver reference combination electrode,
double junction type)*Remark
The general reference electrode (RE-201Z) cannot be used for this titration because
KCl inner solution might come out to sample solution and it causes measurement error.
The inner electrodes of AGR-801Z and MS-231Z use mercury (I) sulfate. When theseelectrodes are disposed, please ask the specialized industrial waste disposal operator.

(2) Reagents
Titrant: 0.01 mol/L Silver nitrate standard solution

3. Measurement procedure(1) Dispense 20 mL of sample into a 100 mL beaker with volumetric pipette.
(2) Add about 20 mL of DI water.
(3) Immerse electrodes and titrate with 0.01 mol/L Silver nitrate standard solution.

4. Measurement conditions and results
Example of titration condition
Cnd. No.
Method ﾞ
Buret No.
Amp No.
D.UnitS- Timer
C.P. mL
T.Timer
D.P. mLEnd Sens
Over mLMax Vol.

1Auto
12
mV
5000800.520sec
mL
sec
mL
mL
mL

Constant No.
1Size
20Blank
0Morality
0.01
Factor
1.005
K35.45
L0UnitPPM
Formula(D-B)*K*F*M*1000/S
Decimal Places
4Auto input parameter

Mode No.
Pre Int
Del K
Del Sens
Int Time
Int Sens
Brt Speed
Pulse

mL
mL
mol/L

805053240sec
mV
sec
mV

None

Measurement results
Number ofSize

Titrant

Chloride ion

Measurement(mL)

Volume (mL)Concentration (ppm)

120

1.294

23.0508

220

1.294

23.05083201.290

22.9796

Statisticcalculation

Avg.

23.03 ppm

SD0.04 ppm

RSD

0.18 %

Example of titration curve

5. Note・Indicator electrodeThe sensitivity of the electrode is important for this measurement. It tends to show the difficulty on theautomatic endpoint detection because of the less sensitivity of normal electrode under highly concentrated
copper sulfate. The silver chloride-coated silver electrode can provide acceptable results on this measurement.
However, it is degraded by prolonged use even if the silver chloride is coated on the electrode. The recoatingof silver chloride is required when the sensitivity of electrode gets lowered.
Keywords: Chloride ion, Precipitation titration, Copper sulfate solution, Copper sulfate plating solution,
Silver chloride coating*Some measurement would not be possible depending on optional configuration of system.