Determination of coal-based liquid phenolic compounds by comprehensive two-dimensional gas chromatography-mass spectrometry/hydrogen flame ionization detection
1Key Takeaways
This standard specifies the method for determining phenolic compounds in coal-based liquid phase samples using comprehensive two-dimensional gas chromatography coupled with mass spectrometry and hydrogen flame ionization detector. It provides detailed procedures for sample preparation, instrument calibration, data acqu…
2Expert Interpretation
An in-depth interpretation of the method principle, instrument configuration, operation process and precision requirements for the determination of phenolic compounds in coal tar and wastewater by comprehensive two-dimensional gas chromatography-mass spectrometry/hydrogen flame ionization detector coupling technology in the GB/T 45372-2025 standard, covering the detection limits and quantitative analysis technical points of 18 components such as phenol, cresol and naphthol.
Technical background and innovative value of the standard
This standard is the first comprehensive two-dimensional gas chromatography-mass spectrometry/hydrogen flame ionization detector combined analytical method for phenolic compounds in coal chemical liquid products in my country. Through the synergistic separation of a one-dimensional non-polar column and a two-dimensional medium-polarity column, combined with mass spectrometry qualitative analysis (characteristic ion peak + double retention time) and hydrogen flame quantitative analysis (internal standard method), the resolution of isomers in complex matrices has been significantly improved.
Comparative Analysis of Core Methods
| Technical Dimensions | Traditional GC-MS | Full Two-Dimensional GC×GC-MS/FID |
|---|---|---|
| Peak Capacity | ~300 | ＞4000 |
| Separation Efficiency | Adjacent Peak Resolution ≤1.5 | Resolution ≥2.8 |
| Qualitative Ability | Single Retention Time + Mass Spectrum | Dual Retention Time + Mass Spectrum/Characteristic Ions |
| Quantitative precision (RSD) | 5-15% | ＜10% |
Analysis of key operating parameters
Chromatographic column system:It must be a combination of a 30m×0.25mm×0.25μm polydimethylsiloxane first-dimensional column and a 1.2m×0.1mm×0.1μm 50% phenyl-methylpolysiloxane second-dimensional column, and the modulation cycle is strictly controlled within 8 seconds to ensure the synchronization of the two-dimensional separation.
Mass spectrometry conditions:EI source ionization voltage 70eV, mass scanning range 45-200m/z, solvent delay 6 minutes to avoid injection solvent interference.
Typical application case
A coal-to-liquids enterprise adopted this standard to detect m-cresol in wastewater:
- 50mL water sample (pH=2) was enriched by solid phase extraction
- 2,6-dichlorophenol was added as internal standard after elution with methanol
- The first-dimensional retention time was 20.65min, and the second-dimensional retention time was 1.31s
- Confirmed by m/z 108 characteristic ion, relative correction factor was 0.459
- Final concentration was 82.4mg/L (RSD=4.7%)
Implementation suggestions
- Preparation of standard solution: Components with low response values such as hydroquinone and naphthol need to increase the sample weight (8-10mg is recommended)
- System verification: Before daily analysis, the separation degree (≥1.8) and relative correction factor deviation (<15%) should be checked with standard solution
- Wastewater pretreatment: The solid phase extraction flow rate is controlled at 5 seconds/drop, and the pH adjustment needs to be accurately controlled with 6 mol/L hydrochloric acid