HIRANUMA APPLICATION DATA

Automatic Titrator

Data No.

N1Feb. 10,
2021

Determination of chloride ion
in cement

CementConcrete
1. Abstract

This report introduces an example of the determination of chloride ion in cement.
This measurement method is described in "Method for measuring chloride" of "Japanese industrial standard
JIS R 5202 Method for chemical analysis of cements". The sample is dissolved in nitric acid, a chloride ion
standard solution and a hydrogen peroxide solution are added, and the sample is heat-treated, and then themeasurement is performed by precipitation titration using a silver nitrate standard solution. The measurements aremade by potentiometric titration using a chloride ion-selective electrode as the electrode for end point detection.

Cl- ＋AgNO3→AgCl＋NO3-2. Configuration of instruments and reagents(1) Configuration of instruments
Main unit: Automatic Titrator COM Series

Electrode: Chloride ion-selective electrodeCLi-081 (Connect to IE-2)

Reference electrodeMS-231Z (Connect to RE-2)*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 MS-231Z use mercury (I) sulfate. When these electrodes aredisposed, please ask the specialized industrial waste disposal operator.

(2) Reagents
Titrant: 0.005 mol/L Silver nitrate standard solution

Additive: Nitric acid (60 %, density 1.38 g/mL)
Hydrogen peroxide (Approx. 30 %)0.005 mol/L Chloride ion standard solution

3. Measurement procedure(1) Take 5 g of sample into a 200 mL beaker and accurately weigh it.
(2) Add about 20 mL of DI water. Then add 12 mL of nitric acid with stirring to dissolve the sample.
(3) Add warm DI water to make 100 mL sample solution.
(4) Add 2 mL of chloride ion standard solution with volumetric pipette.
(5) Add 2 mL of 30 % hydrogen peroxide.
(6) Cover the beaker with watch glass and heat to boil for 1-2 minute. Then cool it to room temperature.
(7) Immerse electrodes and titrate with 0.005 mol/L silver nitrate standard solution.
(8) As blank test, take 2 mL of 0.005 mol/L chloride ion standard solution exactly in a 200 mL beaker, addwarm DI water to make 100 mL, and perform procedure (6) and (7).

4. Measurement conditions and results
Example of titration condition(1) Measurement of blankCnd. No.
MethodBuret No.
Amp No.
D.UnitS- Timer
C.P. mL
T.Timer
D.P. mLEnd Sens
Over mLMax Vol.

1Auto
12mV
5000.2
200
0.5
20

sec
mL
sec
mL
mL
mL

Constant No.
SizeBlank
Morality
FactorKL
Unit
FormulaDecimal Places

60 g0 mL
0.005 mol/L
1.001
00mL

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

2002053280

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

2002053280sec
mVsec
mV

D
3(2) Measurement of sample
Cnd. No.
MethodBuret No.
Amp No.
D.UnitS- Timer
C.P. mL
T.Timer
D.P. mLEnd Sens
Over mLMax Vol.

2Auto
12mV
5000.1150
0.520sec
mL
sec
mL
mL
mL

Constant No.
SizeBlank
Morality
FactorKL
Unit
FormulaDecimal Places

75.0233 g
2.062 mL
0.005 mol/L
1.001
00%(D-B)*F*0.01773/S4secmV
secmV

Measurement results

SampleNumber ofmeasurement

Samplesize(g)1BlankChlorideion(%)

StatisticalCalculation

2.055－

23

SampleTitration
volume(mL)

2.078

－

2.052

Avg.

2.062 mLSD

0.014 mL

RSD

0.69 %

1

5.00986.749

0.0166Avg.

0.0168 %25.0152

6.825

0.0169SD

0.0002 %35.0233

6.836

0.0169RSD

1.03 %

Blank

SampleExample of titration curve

5. Note・Indicator electrode
Chloride ion-selective electrode was used as an indicator electrode for this measurement.
In addition to the above electrode, a silver electrode coated with silver chloride (model: AG-311A) can also be
used for this measurement. However, since the silver electrode coated with silver chloride deteriorates after
long-term use, the electrode potential change near the end point becomes small and unclear. On the other hand,the chloride ion-selective electrode has the advantage that when the sensitivity deteriorates, the sensitivity canbe easily restored by lightly polishing the sensitive membrane with a sandpaper.
Keywords: Chloride ion, Precipitation titration, Cement, JIS R5202*Some measurement would not be possible depending on optional configuration of system.