Propylene glycol is a chemical also known as 1,2-propanediol or 1,2-propanediol. It is a colorless, odorless, sweet organic compound with the chemical formula C3H8O2. It is an important industrial raw material, which can be used to prepare various compounds such as polyether, polyurethane, acrylic acid and acrylate, and can also be used in the preparation of coatings, solvents, spices, medicine and food.
The following are the main properties that need to be tested for propylene glycol and the corresponding detection indicators:
| performance | Detection Indicator |
|---|---|
| Exterior | Appearance is colorless transparent liquid |
| purity | Purity≥99.5% |
| moisture | Moisture content≤0.2% |
| acidity | Acidity (as HAc) ≤0.001% |
| proportion | Specific gravity (20°C) 1.118-1.124 |
| Refractive index | Refractive index (20°C) 1.431-1.435 |
| heavy metal | Lead≤0.1ppm; Copper≤0.1ppm; Zinc≤0.1ppm; Cadmium≤0.1ppm; Mercury≤0.1ppm |
| non-volatile residue | Non-volatile residue ≤0.001% |
| Oxide | Propylene glycol oxide content≤0.05% |
Detection method
The following are the detection methods for the main properties of propylene glycol:
Appearance: directly observe whether the appearance of the sample is a colorless transparent liquid.
Purity: It can be detected by gas chromatography, liquid chromatography, ultraviolet spectrophotometry and other methods.
Moisture: Karl Fischer method, specific gravity method, drying method and other methods can be used for detection.
Acidity: It can be detected by acid-base titration, potentiometric titration, ultraviolet spectrophotometry and other methods.
Specific Gravity: Can be measured using a hydrometer or hydrometer method.
Refractive Index: Can be measured using a refractometer.
Heavy metals: can be detected using atomic absorption spectrometry, inductively coupled plasma mass spectrometry and other methods.
Non-volatile residues: can be detected by drying method, ash method and other methods.
Oxide: It can be detected by titration, spectrophotometry and other methods.
In short, for different performance indicators of propylene glycol, different detection methods need to be adopted, and the detection methods should ensure accuracy and reliability. In the actual production and use process, the quality of propylene glycol should be tested according to the corresponding standard requirements to ensure that it meets the relevant requirements.
