Determination of 21 Volatile Halogenated Hydrocarbons in Ambient Air by Wanyi Technology Gas Chromatography

Volatile halogenated hydrocarbons are a class of organic compounds characterized by volatility and halogen substituents, commonly found in industrial solvents, refrigerants, fire extinguishing agents, and other applications. These substances can enter the human body through the respiratory system. Some of these compounds have been confirmed to exhibit toxicity, mutagenicity, or carcinogenicity, posing potential threats to both the environment and human health. In ambient air, the pollution sources of volatile halogenated hydrocarbons are extensive, including industrial emissions, motor vehicle exhaust, and others.

This article refers to "Determination of Volatile Halogenated Hydrocarbons in Ambient Air by Activated Carbon Adsorption-Carbon Disulfide Desorption/Gas Chromatography" (HJ 645-2013) and adopts Wayeal Gas Chromatograph GC6100 equipped with an ECD detector for the determination of 21 volatile halogenated hydrocarbons in ambient air.

Keywords: Volatile halogenated hydrocarbons; Gas chromatography; ECD detector; Ambient air

1. Experiment Method

1.1 Instrument Configuration

Table 1 Configuration List of Gas Chromatograph

1.2 Experiment Material and Auxiliary Equipment

21 volatile halogenated hydrocarbons standard stock solution (2–1000 μg/mL in carbon disulfide): Purchased as a certified reference standard solution. Store sealed and refrigerated below 4 °C, protected from light.

Carbon disulfide: chromatographic grade;

Analytical balance;

Carrier gas: high-purity nitrogen.

1.3 Test Conditions

Chromatographic column: DB-1 capillary chromatographic column, 60 m × 0.32mm × 1.0μm;

Temperature program: Initial column temperature of 35°C, held for 8 minutes; then increased at 5°C/min to 100°C, followed by an increase at 6°C/min to 200°C, held for 5 minutes;

Column flow rate: 1.5 mL/min;

Inlet temperature: 220 °C;

Detector temperature: 320 °C;

Makeup flow rate: 40mL/min;

Anode purge flow rate: 10mL/min;

Split injection: split ratio 5:1;

Injection volume: 1.0μL.

1.4 Solution Preparation

1.4.2.1 21 volatile halogenated hydrocarbons standard working solution (0.2–100 μg/mL in carbon disulfide):

Accurately pipette an appropriate amount of the 21 volatile halogenated hydrocarbons standard stock solution, dilute it 10-fold with carbon disulfide, and mix thoroughly. Prepare immediately before use.

1.4.2 Linear Standard Working Solutions

Pipette appropriate amounts of the 21 volatile halogenated hydrocarbons standard working solution (0.2–100μg/mL in carbon disulfide) respectively, and dilute with carbon disulfide to prepare a calibration series.

Table 2 Mass Concentrations of the Calibration Series for Volatile Halogenated Hydrocarbons

2. Result and Discussion

2.1 Standard Sample Qualitative Test

Fig 1 Chromatogram of Volatile Halogenated Hydrocarbons Standard Solution (0.02–10μg/mL)

(Elution order: 1: trans-1,2-Dichloroethylene, 2: 1,1-Dichloroethane, 3: cis-1,2-Dichloroethylene, 4: Trichloromethane (Chloroform), 5: 1,2-Dichloroethane, 6: 1,1,1-Trichloroethane, 7: Carbon tetrachloride, 8: 1,2-Dichloropropane, 9: Trichloroethylene, 10: 1-Bromo-2-chloroethane, 11: 1,1,2-Trichloroethane, 12: Tetrachloroethylene, 13: Chlorobenzene, 14: Bromoform, 15: 1,1,2,2-Tetrachloroethane, 16: 1,2,3-Trichloropropane, 17: Benzyl chloride, 18: 1,4-Dichlorobenzene, 19/20: 1,2-Dichlorobenzene + 1,3-Dichlorobenzene, 21: Hexachloroethane.)

Table 3 Chromatographic Parameters of Volatile Halogenated Hydrocarbons Standard Solution (0.02–10μg/mL)

Note: As can be seen from the above chromatogram, the resolutions between the chromatographic peaks of the volatile halogenated hydrocarbons are all greater than 1.0, meeting the requirements for experimental analysis.

2.2 Linearity

Fig 2 Calibration Curves and Correlation Coefficients for Volatile Halogenated Hydrocarbons

Note: The linearity of each component in the volatile halogenated hydrocarbons standard solution is good, with linear correlation coefficients greater than 0.999, which is higher than the standard requirement (linear correlation coefficient ≥ 0.995), meeting the requirements for experimental analysis.

2.3 Precision

Fig 3 Chromatogram of Volatile Halogenated Hydrocarbons Standard Solution (Calibration Curve Point 1)

Fig 4 Chromatogram of Volatile Halogenated Hydrocarbons Standard Solution (Calibration Curve Point 3)

Fig 5 Chromatogram of Volatile Halogenated Hydrocarbons Standard Solution (Calibration Curve Point 4)

Table 4 Chromatographic Parameters for Precision

Note: Six replicate determinations were performed on the volatile halogenated hydrocarbons standard solutions at calibration curve points 1, 3, and 4, respectively. The relative standard deviations obtained were 0.5%–2.8%, 0.3%–1.5%, and 0.4%–0.9%, respectively. The relative standard deviations of the chromatographic peaks for each substance all met the standard requirements.

2.4 Detection Limit

Fig 6 Chromatogram of the Detection Limit Solution (Calibration Curve Point 1)

Table 5 Method Detection Limits and Lower Limits of Determination for Each Component of Volatile Halogenated Hydrocarbons

Eight replicate determinations were performed on the volatile halogenated hydrocarbons standard solution at calibration curve point 1. The calculation results showed that, when the sampling volume was 10L, the method detection limits for the 21 volatile halogenated hydrocarbons ranged from 0.02 μg/m³ to 5.68μg/m³, and the lower limits of determination ranged from 0.08μg/m³ to 22.72μg/m³, meeting the standard requirements.

3. Conclusion

This method employs a Wayeal GC6100 gas chromatograph equipped with an ECD detector to determine 21 volatile halogenated hydrocarbons in ambient air. The experimental results showed that the resolutions between the chromatographic peaks of the volatile halogenated hydrocarbons were all greater than 1.0, meeting the requirements for experimental analysis. The linearity of each component in the volatile halogenated hydrocarbons standard solution is good, with linear correlation coefficients greater than 0.999, which is higher than the standard requirement (linear correlation coefficient ≥ 0.995). The precision test, as well as the method detection limits and lower limits of determination, all met the standard requirements. Therefore, this method can be used for the determination of 21 volatile halogenated hydrocarbons in ambient air.

4. Attention

The solvents used in the experiment, the preparation of standard sample solutions, and the sample pretreatment process should all be carried out in a fume hood. During operation, laboratory personal protective equipment should be worn as required to avoid contact with skin and clothing.