Purity determination of citric acid | Autotitrator COM-A19 - JM Science
HIRANUMA APPLICATION DATA Automatic Titrator Data No. K3 Jul. 14,2020
Organic acid Purity determination of citric acid

1. Abstract

Citric acid is oxycarboxylic acid which has carboxy group (-COOH) and alcoholic hydroxyl group (-OH).

It can be dissolved in water and has acidic property. Citric acid is produced as raw material of organic compound or food additive.

“JIS K8283” prescribes the determination method for the purity of citric acid by the neutralization titration using phenolphthalein indicator. This report introduces an example of the potentiometric titration (formula (1)) with sodium hydroxide standard solution for the purity determination of citric acid monohydrate according to “JIS K8283”.

2. Configuration of instruments and Reagents

(1) Configuration of instruments
  Main unit : Hiranuma Automatic Titrator COM series
  Electrode : Glass electrode GE-101B
Reference electrode RE-201Z
*Instead of the above electrodes, the following electrodes are usable.
・Glass reference combination electrode GR-501BZ…Fixed sleeve type
・Glass reference combination electrode GR-511BZ…Moveable sleeve type
(2) Reagents    
  Titrant : 1 mol/L Sodium hydroxide standard solution

3. Measurement procedure

(1) Add about 2.0 g of sample to a beaker and weigh accurately with 0.1 mg digit.
(2) Add 40 mL of DI water and stirring bar to the beaker Dissolve the sample by stirring.
(3) Immerse electrodes and start titration with 1 mol/L sodium hydroxide standard solution.

4. Measurement conditions and results

Examples of titration conditions

Cndt No 1
Method Auto
Buret No. 1
Amp No. 1
D. Unit pH
S-Timer 5 sec
C.P. mL 20 mL
T Timer 0 sec
D.P. mL 0 mL
End Sens 3000
Over mL 0.3 mL
Max Vol. 40 mL
Constant No. 1
Size 2 g
Blank 0 mL
Molarity 1 mol/L
Factor 1.004
K 70.05
L 0
Unit %
Formula
(D-B)*K*F*M/(S*10)
Decimal Places 3
Auto input Param.
Non
Mode No. 5
Pre Int 0 sec
Del K 5
Del Sens 0 mV
Int Time 3 sec
Int Sens 3 mV
Brt Speed 2
Pulse 40

 

Measurement results

Number of
measurement
Size
(g)
Titrant
volume(mL)
Purity (%)
1 2.0006 28.431 99.948
2 2.0005 28.429 99.946
3 2.0014 28.443 99.950
Statistic
calculation
Avg. 99.95 %
SD 0.002 %
RSD 0.002 %

 

Examples of titration curves

5. Note

(1)Collection of sample
The sample is collected directly to the beaker and weighed accurately. The accuracy of sample collection influences the measurement accuracy. Please note that the sample should be carefully taken and accurately weighed.

(2)Control of titrant
The concentrated sodium hydroxide standard solution is used as titrant in this report. The carbon dioxide gas absorber (soda lime) on reagent bottle has to be regularly exchanged because sodium hydroxide readily absorbs carbon dioxide gas in the air (formula (2)). The standard solution of sodium hydroxide that has absorbed carbon dioxide contains sodium carbonate, and the inflection point on titration curve may be unclear due to buffer capacity of sodium hydrogen carbonate generated in the reaction with an acidic sample (formula (3)).

(3)Reduction of measurement time
The titrant volume was about 28 mL in this report. When the titrant volume is large as described in this report, “CP mL” function can be utilized to reduce the measurement time. It was set to “20 mL” in this report to continuously add the sodium hydroxide standard solution.

Keywords: Citric acid, Sodium hydroxide, Neutralization titration, JIS K8283

*Some measurement would not be possible depending on optional configuration of system.

Hiranuma aquacounter autotitrator com-a19Organic acid

Featured Instruments

Aquacounter Potentiometric Titrator COM-A19 | HiranumaAquacounter Potentiometric Titrator COM-A19 | Hiranuma
Hiranuma Aquacounter Potentiometric Titrator COM-A19 | Hiranuma
Sale price$11,490.00 USD Regular price$12,490.00 USD

Featured Titrators

View all
Aquacounter AQ-300 Coulometric Karl Fischer Titrator | Hiranuma
Hiranuma Aquacounter AQ-300 Coulometric Karl Fischer Titrator | Hiranuma
Sale price$5,800.00 USD Regular price$6,990.00 USD
Aquacounter Volumetric Karl Fischer Titrator MOIVO-A19 | Hiranuma
Hiranuma Aquacounter Volumetric Karl Fischer Titrator MOIVO-A19 | Hiranuma
Sale price$11,990.00 USD Regular price$13,990.00 USD
Aquacounter Coulometric Karl Fischer Titrator MOICO-A19 | Hiranuma
Hiranuma Aquacounter Coulometric Karl Fischer Titrator MOICO-A19 | Hiranuma
Sale price$10,990.00 USD Regular price$12,490.00 USD
Aquacounter Potentiometric Titrator COM-A19 | HiranumaAquacounter Potentiometric Titrator COM-A19 | Hiranuma
Hiranuma Aquacounter Potentiometric Titrator COM-A19 | Hiranuma
Sale price$11,490.00 USD Regular price$12,490.00 USD
Aquacounter AQV-300 Volumetric Karl Fischer Titrator | Hiranuma - JM Science
Hiranuma Aquacounter AQV-300 Volumetric Karl Fischer Titrator | Hiranuma
Sale price$5,800.00 USD Regular price$6,990.00 USD