Optimize Critical Separations in the Analysis of PCBs and PAHs
Polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) are two critical classes of environmental contaminants that pose significant risks to human health and the environment. Europe has established comprehensive regulatory frameworks and monitoring programs to address these pollutants. Continued vigilance and research are essential to mitigate their impacts and protect public health and the environment. Please see references at the end of the article for information on the specific regulations.
Excellent resolution and selectivity for closely eluting compounds is essential for environmental analysis where complex mixtures require high-resolution separations to identify and quantify individual contaminants accurately. The Rxi-XLB, Rtx-440, and the Rxi-SVOCms GC columns were evaluated for optimal separation of select PAHs and PCBs in one method. This evaluation was done using a 30 m x 0.25 mm ID x 0.25 µm column format. Standards were prepared at a concentration of 5 µg/mL.
For this evaluation, the three columns produced varying results. The Rxi-SVOCms and Rtx-440 GC columns produced good resolution for the PAHs, but they did not separate the PCBs as well as the Rxi-XLB GC column (See Table 1; poor or no separation of PCB 28/31 on the Rxi-SVOCms and Rtx-440 GC column). The Rxi-XLB GC column produced the best overall resolution for critical pair separations (see Figure 1). Notably, excellent separation was achieved for PCB 31 and PCB 28 (peaks 8 & 9) and phenanthrene and anthracene (peaks 6 & 7). Other critical separations of interest include benzo[b]fluoranthene and benzo[k]fluoranthene (peaks 23 & 24) and indeno[1,2,3-cd]pyrene, dibenzo[a,h]anthracene (peaks 27 & 28), which the Rxi-XLB GC column was able to resolve to the requirements for regulatory compliance. PCB 180 and benzo[a]anthracene also exhibited the best separation using the Rxi-XLB compared to the other columns that were tested. The total analysis time using the Rxi-XLB GC column was 20 minutes.
Whether analyzing air, water, soil, or sediment methods, the Rxi-XLB GC column provides the resolution necessary to ensure compliance with environmental regulations and to support the protection of public health and the environment.
Table I: Comparison of Critical Pair Resolution* Values in the Analysis of PAH and PCBs
| Peak Pair | Peak Numbers | Rxi-XLB (30 m x 0.25 mm ID x 0.25 µm) |
Rtx-440 (30 m x 0.25 mm ID x 0.25 µm) |
Rxi-SVOCms (30 m x 0.25 mm ID x 0.25 µm) |
| Phenanthrene Anthracene |
6 7 |
2.92 | 2.57 | 2.26 |
| PCB 31 PCB 28 |
8
9 |
1.28 | 0.71 | 0.00 |
| PCB 180 Benzo[a]anthracene |
18 19 |
2.30 | 1.00 | 1.16 |
| Triphenylene Chrysene |
20 21 |
0.71 | 0.56 | 3.23 |
| Benzo[b]fluoranthene Benzo[k]fluoranthene |
23 24 |
0.76 | 1.20 | 1.39 |
| Indeno[1,2,3-cd]pyrene Dibenzo[a,h]anthracene |
27 28 |
0.67 | 0.89 | 1.38 |
| Run Time: | 20.792 min | 20.667 min | 21.677 min | |
*Note: Baseline Resolution = 1.50
Figure 1: Excellent separations were achieved for critical separations in the analysis of PAHs and PCBs on the Rxi-XLB GC column.
| Peaks | tR (min) | Conc. (µg/mL) | |
|---|---|---|---|
| 1. | Naphthalene | 6.134 | 5 |
| 2. | 2-Methylnaphthalene | 7.051 | 5 |
| 3. | Acenaphthylene | 8.353 | 5 |
| 4. | Acenaphthene | 8.617 | 5 |
| 5. | Fluorene | 9.435 | 5 |
| 6. | Phenanthrene | 10.946 | 5 |
| 7. | Anthracene | 11.045 | 5 |
| 8. | PCB 31 | 11.412 | 5 |
| 9. | PCB 28 | 11.451 | 5 |
| 10. | PCB 52 | 11.799 | 5 |
| 11. | Fluoranthene | 12.868 | 5 |
| 12. | PCB 101 | 12.902 | 5 |
| 13. | Pyrene | 13.235 | 5 |
| 14. | 2-Methylfluoranthene | 13.586 | 5 |
| Peaks | tR (min) | Conc. (µg/mL) | |
|---|---|---|---|
| 15. | PCB 118 | 13.765 | 5 |
| 16. | PCB 153 | 13.937 | 5 |
| 17. | PCB 138 | 14.289 | 5 |
| 18. | PCB 180 | 15.07 | 5 |
| 19. | Benzo[a]anthracene | 15.152 | 5 |
| 20. | Triphenylene | 15.197 | 5 |
| 21. | Chrysene | 15.227 | 5 |
| 22. | PCB 194 | 16.127 | 5 |
| 23. | Benzo[b]fluoranthene | 16.799 | 5 |
| 24. | Benzo[k]fluoranthene | 16.832 | 5 |
| 25. | Benzo[e]pyrene | 17.211 | 5 |
| 26. | Benzo[a]pyrene | 17.295 | 5 |
| 27. | Indeno[1,2,3-cd]pyrene | 19.161 | 5 |
| 28. | Dibenzo[a,h]anthracene | 19.209 | 5 |
| 29. | Benzo[ghi]perylene | 19.763 | 5 |
| Column | Rxi-XLB, 30 m, 0.25 mm ID, 0.25 µm (cat.# 13723) |
|---|---|
| Standard/Sample | 2-Methylnaphthalene (cat.# 31285) |
| SV calibration mix #5/610 PAH (cat.# 31011) | |
| PCB congener mix #2 (cat.# 32294) | |
| Diluent: | Methylene chloride |
| Conc.: | 5 µg/mL |
| Injection | |
| Inj. Vol.: | 1 µL splitless |
| Liner: | Topaz Precision inlet liner, 4.0 mm x 6.3 x 78.5 (cat.# 23305) |
| Inj. Temp.: | 240 °C |
| Oven | |
| Oven Temp.: | 40 °C (hold 1 min) to 120 °C at 30 °C/min to 330 °C at 16 °C/min (hold 4 min) |
| Carrier Gas | He, constant flow |
| Flow Rate: | 1 mL/min |
| Detector | MS | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Mode: | Scan | ||||||||
| Scan Program: | |||||||||
| |||||||||
| Transfer Line Temp.: | 250 °C | ||||||||
| Source Temp.: | 300 °C | ||||||||
| Quad Temp.: | 180 °C | ||||||||
| Instrument | Agilent 7890A GC & 5975C MSD | ||||||||
| Sample Preparation | The sample was in a 2 mL short-cap, screw-thread vial (cat.# 21143) and capped with a short-cap, screw-vial closure (cat.# 24495). | ||||||||
References:
- iTeh, Inc., EN 17322:2020, Environmental Solid Matrices-Determination of polychlorinated biphenyls (PCB) by gas chromatography-mass selective detection (GC-MS) or electron-capture detection (GC-ECD), 28 July 2020. https://standards.iteh.ai/catalog/standards/cen/bd16cd16-70b0-4f08-8ad6-e3d3e125c05b/en-17322-2020
- International Organization for Standardization, ISO 18475:2023, Environmental solid matrices- Determination of polychlorinated biphenyls (PCB) by gas chromatography-mass selective detection (GC-MS) or electron-capture detection (GC-ECD), October 2023. https://www.iso.org/standard/84177.html
For an optimized analysis of PAHs on the Rxi-SVOCms, see our article, "Optimized Polycyclic Aromatic Hydrocarbon (PAH) Analysis by GC-MS".