HIRANUMA APPLICATION DATA

Data No. B21

Automatic Titrator

Nov. 14,2018

Quantitative determination of sodium citrate

Drugs and Medicines

1. Abstract
Sodium citrate is used as anticaking agent for blood in pharmaceutical field. Quantitative determination
method for sodium citrate is stipulated in Japanese Pharmacopoeia.
This report introduces an example of potentiometric titration for sodium citrate that well-dried sample isdissolved in acetic acid, then it is titrated with perchloric acid - acetic acid standard solution.

C6H5Na3O7＋3HClO4→C6 H8 O7＋

3NaClO4

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

COM SeriesElectrodes: Glass electrodeGE-101B**: Reference electrodeRE-201Z**Inner solution has to be changed to saturated sodium perchlorate inacetic acid.
**Glass-reference combination electrode GR-511BZ is also usable.
(2) Reagents
Titrant: 0.1 mol/L perchloric acid - acetic acid standard solution

Titration solvent: 50 mL of acetic acid (reagent grade)

3. Measurement procedure(1) Take about 0.1 g of sodium citrate hydrate (C6H5Na3O7・2H2O) and dry it at 180 °C for 2 hours.
(This procedure removes the hydrates.)(2) Take about 0.2 g of the above dried sample into 100 mL tall beaker and weigh accurately.
(3) Add 30 mL of acetic acid and dissolve sample by stirring.
(4) Immerse the electrodes and titrate with 0.1 mol/L perchloric acid - acetic acid standard solution.
Additionally, perform the blank test with the same procedure of sample measurement.

4. Measurement conditions and results
Examples of titration conditions
Measurement of blank
Cndt No.
MethodBuret No.
Amp No.
D. Unit
S-Timer
C.P. mLT Timer
D.P. mLEnd Sens
Over mL
Max.Vol.

1Auto
11mV
100001000
0.1
1.0sec
mL
sec
mL
mL
mL

ConstantNo.
SizeBlank
Molarity
FactorKL

1000.1000
1.004
00UnitFormulaDigitsAuto In Pram.

mL
D
3Nong
mL
mol/L

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

1700053216sec
mV
sec
mV

Measurement of sodium citrate
Cndt No.
MethodBuret No.
Amp No.
D. Unit
S-TimerC.P. mL
T Timer
D.P. mLEnd Sens
Over mL
Max.Vol.

2Auto
11mV
10
2050.0300
0.340sec
mL
sec
mL
mL
mL

ConstantNo.
SizeBlank
Molarity
FactorKL

200.0100
0.1000
1.004
86.02
0Unit
FormulaDigitsAuto In Pram.

g
mL
mol/L

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

805053240sec
mV
sec
mV%(D-B)*K*F*M/(S*10)
3Non

Measurement results
Measurement of blank

Measurement of sample

Number ofSize

Titrant

Number ofSize

Titrant

ConcentrationMeasurement(g)

Volume (mL)

Measurement(g)

Volume (mL)(%)

1-0.01010.2029

23.41999.6402-0.010

20.2052

23.67599.60130.2052

23.67099.580Avg.
0.010 mL
(Blank)Statistic
calculation

Avg.

99.61 %

SD

0.0304 %RSD

0.03 %

Measurement of blank

Measurement of sample

Examples of titration curves

5. Note(1) Effect of water on perchloric acid titration
Water mixed in a measurement system affects to the reaction system of perchloric acid titration
because of the leveling effect, which results in a negative effect such as lowered quantitative performance orgetting less sensitivity around the end point. Therefore please take care not to mix water in the measurement
system. Reference electrode for non-aqueous titration should be prepared as described in the following item(2), because water of KCl solution commonly used as inner solution for reference electrode could be mixed inthe measurement system.
(2) Preparation of inner solution for reference electrodeThe inner solution of the reference electrode RE-201Z is filled with 4 M KCl aqueous solution whenpurchased. This inner solution have to be replaced to saturated sodium perchlorate in acetic acid solution forthis measurement. Replacement procedure is described below.
i) Prepare the saturated solution of sodium perchlorate in acetic acid with reagent grade.
ii) Discharge inner solution from reference electrode RE-201Z and wash inside it with water and thenacetic acid.
iii) Fill the prepared inner solution into reference electrode from the supply port.
iv) Cure the electrode for one day before use.
(3) Influence of experiment temperature on perchloric acid titration
Acetic acid used as a solvent for the titrant has a relatively large thermal expansion coefficient. Whenthe temperature changes by 1 °C, the titrant causes a volume change of 0.1 %. Factor titration and sample
measurement should be performed at the same room temperature as much as possible for accurate
measurement. (Please refer to application data B19 in regards to factor correction.)
Keywords: Sodium citrate, Perchloric acid titration, Non-aqueous titration*Some measurement would not be possible depending on optional configuration of system.