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

4 Results and Discussion

4.1 Experimental Results

Calculation formula:

 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]