Determination of Ethylene Glycol, Diethylene Glycol, and Triethylene Glycol Using Wayeal Gas Chromatography

In the field of modern chemical industry, ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG), as typical representatives of the polyol family, have integrated into every aspect of human life due to their unique physical and chemical properties. The most common application of ethylene glycol is as a key component in automotive antifreeze and coolants. Meanwhile, ethylene glycol serves as a primary raw material for producing polyester fibers (such as polyester) and polyester plastics (like those used in mineral water bottles), playing a crucial role in the textile and packaging industries. Diethylene glycol and triethylene glycol are important derivatives of ethylene glycol. Diethylene glycol is commonly used in industry as a gas dehydrating agent, an aromatic hydrocarbon extraction solvent, and in polyurethane synthesis to enhance material flexibility. It is also found in products such as brake fluids and cosmetic humectants. Due to its high boiling point and strong hygroscopicity, triethylene glycol serves as a "drying guardian" in natural gas dehydration processes, achieving an efficiency of over 99.9%.

This study employed the Wayeal gas chromatograph GC6100 equipped with a hydrogen flame ionization detector (FID) to determine the contents of ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) in the samples.

Keywords: ethylene glycol; diethylene glycol; triethylene glycol; gas chromatography; FID detector.

1. Experiment Method

1.1 Instrument Configuration

Table 1 Gas Chromatograph Configuration List

1.2 Experiment Material and Auxiliary Equipment

Ethylene glycol reference standard

Diethylene glycol reference standard

Triethylene glycol reference standard

Ethanol (Chromatographic grade)

Carrier gas: High-purity nitrogen

Hydrogen generator;

Air generator.

1.3 Test Conditions

Gas Chromatography Conditions

Chromatographic column: Wax capillary column, 30m×0.32mm×0.5μm;

Temperature programming: The initial column temperature was set at 80°C and held for 1 minute, then increased to 220°C at a rate of 15°C/min and held for 10 minutes.

Column flow rate: 2.0 mL/min

Injection port temperature: 250°C

Detector temperature: 250℃

Air flow rate: 300mL/min

Hydrogen flow rate: 40mL/min

Make-up gas flow rate: 10mL/min

Split injection: Split ratio 90:1

Injection volume:1μL

2. Result and Discussion

2.1 Standards Qualitative Test

Fig 1 Chromatogram of Ethylene Glycol Reference Solution

Fig 2 Chromatogram of Diethylene Glycol (diglycol) Reference Solution

Fig 3 Chromatogram of Triethylene Glycol Reference Solution

Table 1 Chromatography Parameters of Reference Standard Solutions

Note: As shown in the above chromatogram, all component peaks are well separated. The theoretical plate number for each component peak exceeds 30000, meeting the requirements for experimental analysis.

2.2 Sample Test

Qualitative analysis of retention times for each component based on standard samples indicates that the largest chromatographic peak in Sample 2 is not ethylene glycol. Details are showed in Figures 5-1 and 5-2. Using the normalization method for calculation, the total content of all detected components in the sample is regarded as 100%. The content of each component is expressed as the percentage of its peak area relative to the total peak area. Based on this approach, the contents of ethylene glycol, diethylene glycol, and triethylene glycol in the sample were calculated. Details are presented in Table 2.

Fig 4 Test Chromatogram of Sample 1 Solution

Fig 5-1 Comparison Chromatogram Between Sample 2 Solution and Ethylene Glycol Reference

Fig 5-2 Comparison Chromatogram Between Sample 2 Solution and Ethylene Glycol Reference

Fig 6 Test Chromatogram of Sample 2 Solution

Fig 7 Test Chromatogram of Sample 3 Solution

Fig 8 Test Chromatogram of Sample 4 Solution

Fig 9 Test Chromatogram of Sample 5 Solution

Table 2 Content of Each Component in Sample Solution

3. Conclusion

This experiment employed the Wayeal Gas Chromatograph GC6100 equipped with an FID detector to determine ethylene glycol, diethylene glycol, and triethylene glycol in the samples. The experimental results demonstrated that the chromatographic peaks of all components were well separated, with theoretical plate numbers exceeding 30000, meeting the requirements for analytical purposes. Qualitative identification of each component was performed based on retention times obtained from reference standard tests.

Quantitative analysis was conducted using the normalization method, and the contents of ethylene glycol, diethylene glycol, and triethylene glycol in each sample were calculated accordingly, as detailed in Table 2. These results confirm that the Wayeal GC6100 gas chromatograph is fully capable of meeting the detection requirements for ethylene glycol, diethylene glycol, and triethylene glycol in the samples.

4. Attention

4.1 During practical operations, laboratory protective equipment must be worn as required to avoid contact with skin and clothing.

4.2 Analytical-grade standards and samples are hygroscopic. They should be promptly sealed after use and stored in a cool, dry, well-ventilated place, protected from light.