| HIRANUMA APPLICATION DATA | Automatic Titrator | Data No. | A2 | Sep.12,2018 |
| FOOD | Successive measurement of acid and salt in dressing |
1.Abstract
An example of successive determination of concentration of acid and salt chloride in dressing is introduced here. Acid and salt are determined as acid and sodium chloride.
At first, titration of acetic acid with sodium hydroxide titrant is performed (Formula (1)). Next, the sample solution is acidified by adding nitric acid, then titration of sodium chloride is performed with silver nitrate titrant (Formula (2)).
| CH₃COOH ＋ NaOH → CH₃COONa ＋ H₂O | ・・・(1) |
| NaCl ＋ AgNO₃ → AgCl ＋ NaNO₃ | ・・・(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 COM series(w/ one buret) | |
| Option | : | Buret 1 set, Dispenser (Peristaltic pump type) 1 set | |
| Electrodes | : | Glass electrode GE-101B, Connect to IE-1. Silver reference combination electrodeAGR-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 of acid, (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
(2) Dispense 10 % nitric acid
(3) Titration of salt with silver nitrate standard solution
Measurement results
| Measurement No. |
Size (g) |
Titrant volume (mL) |
Acid (%) |
Titrant volume (mL) |
Salt (%) |
|---|---|---|---|---|---|
| 1 | 1.0854 | 2.944 | 1.637 | 10.905 | 5.895 |
| 2 | 1.0786 | 2.934 | 1.642 | 10.831 | 5.892 |
| 3 | 1.0739 | 2.923 | 1.643 | 10.776 | 5.888 |
| Statistical result |
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 the measurement 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 is a 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 why AGR-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.
