HIRANUMA APPLICATION DATA

Factorstandardization

Automatic Titrator

Data No.

O2Feb. 03,
2022

Standardization of sodium hydroxide titrant

1. Abstract
The measurement method of acidic substance by neutralization titration using a sodium hydroxide
standard solution is widely used in the titration analysis. Factors are indicated on the commercially available
standard solution for volumetric analysis. The factor determination is required when the standard solutions areprepared in the laboratory. Also it is effective to check the repeatability by the factor measurement using astandard material to check the performance of titrator system. Japanese Industrial Standard JIS K 8001 and theJapanese Pharmacopoeia describe that amidosulfuric acid, which is a standard material for a volumetricanalysis, should be used for the factor determination of sodium hydroxide standard solution. As a simpler
method, it is also possible to use a hydrochloric acid standard solution, having the same molar concentration as
sodium hydroxide and a known factor, as the standard substance.
In this report, the above two types of standardization methods were performed. When amidosulfuric acidis used for the standard substance, firstly a known amount of amidosulfuric acid is dissolved in pure water. And
then potentiometric titration is performed with 0.1 mol/L sodium hydroxide standard solution to determine itsfactor. 1 mol of amidosulfuric acid and 1 mol of sodium hydroxide react quantitatively according to Eq. (1) andshow an inflection point on the titration curve.
(NH2)HSO3 ＋ NaOH → (NH2)NaSO3 ＋ H2O･･･(1)

When hydrochloric acid standard solution with known factor is used for the standard substance, firstly the0.1 mol/L hydrochloric acid standard solution is taken into a beaker with a volumetric pipette and it is diluted
with pure water. And then potentiometric titration is perform with 0.1 mol/L sodium hydroxide standard
solution to determine the factor. 1 mol of hydrochloric acid and 1 mol of sodium hydroxide react quantitatively
according to equation (2) and show an inflection on the titration curve.
HCl ＋ NaOH → NaCl ＋ H2O･･･(2)1) Japanese Pharmacopoeia Eighteenth Edition
2) Japanese Industrial Standard JIS K8001 General rules for test methods of reagents

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

COM SeriesElectrodes: Glass electrodeGE-101B

Reference electrodeRE-201Z(2) Reagents
Titrant: 0.1 mol/L (0.1 N) sodium hydroxide standard solution (Buret No. 1)

Standard material : Amidosulfuric acid, standard material for volumetric analysis(Certified value of purity in this report: 100.00 %)0.1 mol/L (0.1 N) hydrochloric acid standard solution (f = 1.003)

3. Measurement procedure(1) Procedure using amidosulfuric acid as a standard substancei)

Take about 0.1 g of amidosulfuric acid into a 100 mL beaker and weigh it accurately to 0.1 mg digits.

ii) Add 50 mL of DI water and a stirrer bar to the 100 mL beaker to dissolve the sample.
iii) Immerse the electrodes and start the measurement. Titration is performed with a 0.1 mol/L sodiumhydroxide standard solution, and the inflection point on the titration curve is detected as the end point.
iv) Perform the blank test with the same procedure of sample measurement.
(2) Procedure using 0.1 mol/L hydrochloric acid standard solution as a standard substancei)

Take 10 mL of 0.1 mol/L hydrochloric acid standard solution accurately into a 100 mL beaker withvolumetric pipette.

ii) Add 50 mL of DI water and a stirrer bar to the 100 mL beaker.
iii) Immerse the electrodes and start the measurement. Titration is performed with a 0.1 mol/L sodiumhydroxide standard solution, and the inflection point on the titration curve is detected as the end point.
iv) Perform the blank test with the same procedure of sample measurement.

4. Measurement conditions and results
Examples of titration conditions
Blank measurement

Cndt No.
1MethodAuto
ConstantNo.
1Mode No.
16 *1Buret No.
1Size0 gPre Int0 sec
Amp No.
1Blank0 mL
Del K
0D. Unit
pHMolarity
0.1 mol/L
Del Sens
0 mV
S-Timer
20 secFactor0Int Time
3 sec
C.P. mL
0 mL
K0Int Sens
3 mV
T Timer
0 sec
L0Brt Speed
2
D.P. mL
0 mL
Pulse
16End Sens
300
Unit
mL
Over mL
0.3 mL
FormulaD
Max.Vol.
1 mL
Digits3*1: Since the maximum change in electrode potential is shown at the first drop of this blank titration, the end
point is detected in the first drop or less volume. To detect this maximum change as an end point, set Mode No.
to which the blank mode function is assigned, Mode No.12-19 for COM-A19.

Factor standardization measurement with amidosulfuric acid

Cndt No.
MethodBuret No.
Amp No.
D. Unit
S-Timer
C.P. mLT Timer
D.P. mLEnd Sens
Over mL
Max.Vol.

2
Auto
1
1
pH
2000
1300
0.3
20sec
mL
sec
mL

ConstantNo.
SizeBlank
Molarity
FactorKL

200.010.1
1.000097.09
0Mode No.
Pre Int
Del K
Del Sens
Int TimeInt Sens
Brt SpeedPulsegmLmol/L*2*3409033240secmVsecmVUnit
Fact2mL
FormulamL
S*F*1000/(K*M*(D-B))
Digits4*2: Purity of amidosulfuric acid / 100*3: It is the mass (g) of amidosulfuric acid that reacts with 1 mol of sodium hydroxide by the reaction formula(1), which is a formula amount (97.09) of amidosulfuric acid.
Factor standardization measurement with 0.1 mol/L hydrochloric acid standard solution

Cndt No.
3
MethodAuto
ConstantNo.
3Buret No.
1Size
10 mL
Amp No.
1Blank
0.01 mL
D. Unit
pHMolarity
0.1 mol/L
S-Timer
5 sec
Factor
1.003 *4C.P. mL
0 mL
K0T Timer0 sec
L0D.P. mL
1 mL
End Sens
500Unit
Fact1
Over mL
0.5 mL
FormulaS/(D-B)*FMax.Vol.
20 mL
Digits4*4: Factor of 0.1 mol/L hydrochloric acid standard solution

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

409033240sec
mVsec
mV

Measurement results
Results of factor standardization measurement
Standard
material

Measurement
No.

Samplesize

Titrant
volume (mL)Blank

1212310.1174 g
0.1190 g
0.1098 g

0.010
0.010
12.03912.24311.32410.009210 mL

Amidosulfuricacid
0.1 mol/Lhydrochloricacid

3Factor

Statistical result
Avg.

0.01 mL

Avg.
SDRSD
Avg.

10.0081.00521.00190.99961.00311.0032

SD

1.002
0.003
0.28 %
1.003
0.000210.0111.0029RSD

0.02 %

BlankAmidosulfuric acid

0.1 mol/L hydrochloric acid

Examples of titration curves

5. Note(1) About the standard material
Amidosulfuric acid is used for the standardization of sodium hydroxide or potassium hydroxide standard
solution in neautrarization titration. The standard material for volumetric analysis comes with a certificate
value of the purity and uncertainty. If these certification and traceability are required for the management of
test result, such as quality records, the standard material for volumetric analysis is used. It is necessary to
prepare the standard material with pretreatment such as drying as described in its instruction before use.
For the hydrochloric acid standard solution with a known factor, either prepare it in the laboratory andstandardize it according to the procedure of Application No. O1, or procure the one supplied by the reagent
manufacturer as a standard solution for volumetric analysis. The measurement procedure is easier than using
solid standards such as amidosulfuric acid.

Keywords：Factor standardization, Neutralization titration, Sodium hydroxide, Amidosulfuric acid

※Depend on the configuration of instrument, ,some of measurement may not possible