HIRANUMA APPLICATION DATA

Data No.

Automatic Titrator

A2

Sep. 12,2018

Successive measurement ofacid and salt in dressing

FOOD

1. Abstract
An example of successive determination of concentration of acid and salt chloride in dressing is introduced here. Acidand salt are determined as acetic acid and sodium chloride.
SampleElectrodes: Glass Electrode, Reference Electrode
Acid Measurement

Buret No.1: Sodium hydroxide standard solution

pH adjustment *Dispenser No.2: Dispense 5 ml of 10 % Nitric acid
Electrodes: Silver electrode, Silver reference electrode

Salt Measurement

Buret No.3: Silver nitrate standard solution

At first, titration of acetic acid with sodium hydroxide titrant is performed (Formula (1)). Next, the sample solution isacidified by adding nitric acid, then titration of sodium chloride is performed with silver nitrate titrant (Formula (2)).
CH3COOH ＋ NaOH
NaCl ＋ AgNO3→→

CH3COONa ＋ H2O

AgCl ＋ NaNO3・・・(1)・・・(2)* The titration for sodium chloride with silver nitrate has to be performed under acidic condition using nitric acid.

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

Option： Buret 1 set, Dispenser (Peristaltic pump type) 1 set

Electrodes： Glass electrode GE-101B, Connect to IE-1.

COM series (w/ one buret)

Silver reference combination electrode AGR-811Z (Double junction type)
Connect to IE-2 and RE-2.
(2) Reagents
Titrant： 0.1 mol/L Sodium hydroxide standard solution (Measurement of acid)
0.1 mol/L Silver nitrate standard solution (Measurement of salt)

Additive solution： 10 % Nitric acid solution

3. Measurement procedure(1) Take 1 g of sample into 100 ml beaker and weigh it exactly.
(2) Add 50 ml of DI water.
(3) Immerse the electrodes and start titration. The following successive titration processes are performed. [(i) titration ofacid, (ii) dispense nitric acid, (iii) titration of salt]

4. Measurement conditions and results
Examples of titration conditions(1) Titration of acid with sodium hydroxide standard solution
Condition No. 1
MethodAutoConstant No.

1

Mode No.

41.0739 g

Pre Int

0 sec

0 mL

Del K

90.1 mol/L

Buret No.

1SizeAmp No.

1BlankD.UnitpHMolality

Del Sens

0 mVS-Timer5 sec

Factor

1.005

Int time

3 sec

CP mL

0 mL

K

60.05

Int Sens

3 mVT Timer

0 sec

L0Buret Speed

20 mL

Unit%Pulse

D.P. mLEnd Sens

200Formula

Over mL

0 mL

Max. Vol.

20 mL(D-B)*K*F*M/(S*10)

Digits400.05 mL

3Auto input Parameter

None(2) Dispense 10 % nitric acid.
Condition No. 2
MethodDispBuret No.

2S-Timer

0sec

Disp. Vol.

5mL

(3) Titration of salt with silver nitrate standard solution
Condition No.3
MethodBuret No.

AutoConstant No.

3Mode No.

4 sec

1.0739 g

Pre Int03Size

Amp No.

2Blank

0 mL

Del K

9 mV

D.UnitmV

Molality

0.1 mol/L

Del Sens

0 sec

S-Timer

5 sec

Factor1.004

Int time

3 mV

CP mL

0 mL

K

58.44

Int Sens

3T Timer

0 sec

L0Buret Speed

2

DP mL

0 mL

Unit%

Pulse

40

End Sens

200

Over mL

0.3 mLMax. Vol.

20 mL

Formula(D-B)*K*F*M/(S*10)

DigitsAuto input Parameter3None0.05 mL

Measurement results
Measurement

Size

Titrant

Acid

Titrant

Salt

No.

(g)

volume (mL)(%)

volume (mL)(%)

11.0854

2.944

1.637

10.9055.895

21.0786

2.934

1.642

10.8315.892

31.0739

2.923

1.643

10.776

5.888

Statisticalresult

Avg.

1.64 %

5.89 %

SD

0.0032 %0.0035 %RSD

0.20 %

0.06 %

Measurement of acid

Measurement of salt

Examples of titration curves

5. Note(1) Homogeneity of samples
The unevenness of sample, because the dressing often containing solid and oil components, may effect to themeasurement accuracy. Stir the sample adequately with mixer or homogenizer to uniform the sample before
measurement.
(2) Electrodes
Electrodes GE-101B and AGR-811Z are used for successive measurement of acid and salt in this report. AGR-811Z isa combination electrode. Reference compartment of AGR-811Z is made of Ag/AgCl inner electrode with double
junction system. Ag/AgCl inner electrode immersed in KCl inner solution is required for electrode to perform pH
calibration. On the other hand, KCl inner solution is a contaminant source for salt measurement. That is the reason whyAGR-811Z equipped double junction system must be used for this titration.
Keywords：Dressing, Acid, Salt

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