26

2025

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05

Determination of moisture content in propylene glycol by volumetric method


1. Preface
When determining some sugar flavor samples, ethylene glycol is used as the solvent. The moisture content in it has a significant impact on the content of components in the sample, so it is necessary to accurately measure the moisture content. This method directly uses two-component ethanol reagent as the solvent. The measurement results have good repeatability, meet the normal moisture requirements of this type of product, and are convenient, fast, easy to operate, fully meeting the water content determination requirements.
2 Instruments and equipment
2.1 Instruments
JH-T6 fully automatic potentiometric titrator, dual platinum electrodes, 5mL titration unit.
2.2 Reagents
Karl Fischer titrant, ethanol solvent [Ethanol (90%-100%), containing 2-methylimidazole (1%-5%), liquefied sulfur dioxide (1%-5%)}
3 Experimental Methods
3.1 Experimental Procedures
3.1.1 Through the liquid discharge device of the moisture titrator, the residual liquid is removed. Then, 50mL of solvent ethanol is added to the titration cup, with the solvent covering the electrode. After setting the parameters, the instrument starts the pre-titration. When the instrument is in standby mode, click on the system injection and open the rubber stopper of the feeding port. Quickly add an appropriate amount of the sample (the amount of sample depends on the moisture content of the sample), immediately cover the rubber stopper, click "Start Measurement", and use Karl Fischer. Titrate with the titrant to the endpoint, input the sample weight, and calculate the moisture content of the sample.

3.2 Instrument Parameters

Stirring speed: 35%


Finish line: 130mv

Control area: 300mv

Drift value: 25ug/min

Mixing time: 80s


Termination type: Absolute drift cessation

Start liquid addition rate: Normal

Final volume: 10mL

Maximum liquid loading rate: 5mL/min

Minimum liquid addition rate: 80 μ l /min

 

4 Results and Discussion

4.1 Experimental Results

Calculation formula:

Sample

Number


Concentration of titrant

(mg/mL)


Sampling quantity

(g

Titration volume

(mL)

 

Moisture (%)

1

 

 

5.0

2.239

0.198

0.042

2

2.536

0.221

0.042

3

2.391

0.205

0.041


 the formula:

 

X - represents the moisture content of the sample (%);

 

V1 - The volume (mL) of titration liquid consumed when titrating the sample; m - The weighing amount of the sample (g);

T - represents the concentration of the titrant (mg/mL).

 

 

4.2 Conclusion

 

The moisture content of propylene glycol was measured by the JH-T6 fully automatic potentiometric titrator. The data repeatability was good. The instrument can automatically control the titration process, determine the endpoint and calculate the results, reducing the errors caused by human factors. It has the characteristics of being fast and simple.

References

 

[1]GB /T606-2003 General Chemical Reagents - Moisture, Karl. Pension Law [S]

Keyword:

Determination of moisture content in propylene glycol by volumetric method,fully automatic potentiometric titrator,,potentiometric titrator,titrator