GC-FID Method Note – Active Compounds (Xil-350)
Analysis of Active Compounds (Restek Test Mix Xil-350) in the miniGC
Introduction
This test mix is used to test activity in the flow path, from the injection port all the way through to the detector. If there are too many active sites in the system, the peak shapes will be poor. This particular set of runs was also used to demonstrate repeatability of runs with respect to retention times and peak areas as well as comparability to results from a traditional GC when using the same method and essentially the same column (we replace the fused silica column with its metal capillary version so that the column can be wound in a smaller radius to fit in the smaller miniGC oven).
Reference Method
(https://www.restek.com/en/pages/chromatogram-view/GC_CF01131)
| Column | Rxi-5Sil MS, 30 m, 0.25 mm ID, 0.25 µm (cat.# 13623) |
| Sample | Rxi-5Sil MS/XLB column test mix (cat.# 35226) |
| Injection | |
| Inj. Vol.: | 1.0 µL split (split ratio 60:1) |
| Liner: | 4 mm recessed single taper (cat.# 20983) |
| Inj. Temp.: | 250 °C |
| Oven | |
| Oven Temp.: | 125 °C |
| Carrier Gas | He, constant pressure |
| Linear Velocity: | 36 cm/sec @ 125 °C |
| Detector | FID @ 320 °C |
| Instrument | Agilent/HP6890 GC |
Reference Standard
350ug/mL of each in methylene chloride
Xil-350 Column Test Mix Restek PN: 35226
Reference Chromatogram
Peaks:
- 2-Ethylhexanoic acid
- 1,6-Hexanediol
- 4-Chlorophenol
- Tridecane
- 1-Methylnaphthalene
- 1-Undecanol
- Tetradecane
- Dicyclohexylamine
miniGC Method
| Column | MXT-5, 30 m, 0.25 mm ID, 0.25 µm (cat.# 70223-LUC25) |
| Sample | Rxi-5Sil MS/XLB column test mix (cat.# 35226) |
| Injection | |
| Inj. Vol.: | 1.0 µL split (split ratio 25:1) |
| Liner: | 4 mm low pressure drop precision inlet liner w/ wool (cat.# 23309) |
| Inj. Temp.: | 250 °C |
| Oven | |
| Oven Temp.: | 125 °C |
| Carrier Gas | He, constant pressure |
| Linear Velocity: | 36 cm/sec @ 125 °C |
| Detector | FID @ 320 °C |
| Instrument | Lucidity miniGC |
miniGC Chromatograms
Results
The 3 injections of the Xil-350 Test Mix show 1) comparable chromatograms to the reference chromatograms generated on a traditional GC-FID, 2) good repeatability on multiple injections, and 3) good peak shapes of each compound indicating no active sites in the miniGC pathway.
The peaks for the 8 compounds in the test mix match from the miniGC to the traditional GC. It can easily be determined which peak correlates to which and the relative retention times seem to match up fairly well. This demonstrates the ease with which a method in a traditional GC can be transferred to a miniGC and by using the same method and same column as in the traditional system the results can be referenced back against generated on traditional GCs. This experiment also demonstrates the ease with which a user can match results run on a metal capillary column versus a fused silica column. In the reference method an Rxi-5Sil MS fused silica column is used and in the miniGC method an MXT-5 metal capillary column of the same dimensions is used, yet the results from the two sets of runs are very comparable.
More results from the miniGC can be found here: https://luciditysystems.com/products/minigc/minigc-results/
More information on the miniGC can be found here: https://luciditysystems.com/products/minigc/
To see the miniGC in operation go here: https://luciditysystems.com/products/minigc/minigc-interface/