Supelco SLB®-IL60 Ionic Liquid GC Columns: Lower FID Bleed

By: Leonard M. Sidisky, Katherine K. Stenerson, and Michael D. Buchanan, Reporter US Volume 33.3

The SLB®-IL60 gas chromatography (GC) column is based on an ionic liquid stationary phase platform, and displays desirable features that existing non-ionic liquid columns do not. This is the fourth of several Reporter articles which explore various aspects of this column[1, 2, 3].

Higher temperature GC columns are desirable, as they may allow decreased analysis times, elevated bake-out to remove large non-target compounds, and analysis of higher boiling compounds. However, higher oven temperatures also tend to accelerate the amount of column bleed. When working with a flame ionization detector (FID), excessive bleed is undesirable as it lowers the signal-to-noise, resulting in a loss of sensitivity. Column manufacturers routinely list the maximum temperature a column can safely be used at before the level of column bleed renders the column un-useable.

To illustrate the lower FID bleed characteristic of the SLB-IL60 column, it was compared directly to five popular commercially available PEG columns, each from a different manufacturer. All columns were 30 m x 0.25 mm I.D., 0.25 µm dimensions, except the SLB-IL60 column, which has a 0.20 µm film thickness. Table 1 shows the maximum temperature limits for all columns tested. Complete specifications of SLB-IL60 columns are shown in Table 2.

Table 1. Maximum Temperature Limits*
Column
Isothermal °C
Programmed °C
PEG 1
280
280
PEG 2
260
270
PEG 3
250
260
PEG 4
250
260
PEG 5
280
300
SLB-IL60
300
300
* Obtained from paperwork included with commercial columns.

 

Table 2. SLB-IL60 Column Specifications
Application Modified (deactivated) version of SLB-IL59 provides better inertness. Selectivity more polar than PEG/wax phases, resulting in unique elution patterns. Higher maximum temperature than PEG/wax columns (300 °C compared to 270-280 °C). Excellent alternative to existing PEG/wax columns. Also a good GCxGC column choice. Launched in 2012.
USP Code None
Phase Non-bonded; 1,12-Di(tripropylphosphonium)dodecane bis(trifluoromethylsulfonyl)imide
Temp. Limits 35 °C to 300 °C (isothermal or programmed)


FID Bleed Comparison
Following column installation, conditioning, and the analysis of two test mixes to demonstrate the column and system were working properly, a temperature programmed bleed run was performed. The final temperature used for each column was based on its programmed temperature limit. An overlay of all six chromatograms is displayed in Figure 1. As shown, only the PEG 4 column exhibited a lower FID bleed level than the SLB-IL60, but did so at a final oven temperature that was 40 °C lower. The PEG 5 column exhibited the highest FID bleed, which is surprising considering it has a 300 °C limit for progammed use.

Figure 1. FID Bleed Chromatograms

CONDITIONS: PEG columns: 30 m x 0.25 mm I.D., 0.25 µm; SLB-IL60 column: SLB-IL60, 30 m x 0.25 mm I.D., 0.20 µm (29505-U); oven: 50 °C (2 min), 15 °C/min to column programmed temperature limit (10 min); inj. temp.: 250 °C; carrier gas: helium, 1 mL/min; detector: FID, at column programmed temperature limit; injection: 1 µL, splitless; liner: 4 mm I.D., split/splitless type, single taper wool packed FocusLiner™ design; sample: methylene chloride


Conclusion
Columns based on polyethylene glycol phase chemistry are widely used for a variety of applications (such as solvents and FAMEs). Traditional PEG phase chemistry requires PEG columns to be used at maximum temperatures of 260-280 °C, well-below the 300 °C limit of the SLB-IL60 column. Most of the PEG columns tested generated FID bleed which exceeded that of the SLB-IL60 column, even though the SLB-IL60 column was used at a higher oven temperature. The PEG 5 column incorporates a non-traditional PEG phase, and also has a 300 °C rating, but exhibited a much higher FID bleed level. These data show the SLB-IL60 column exhibits lower column bleed characteristics for FID use, compared to existing PEG columns..

Featured Products
Description Cat. No.
SLB-IL60 GC Columns
15 m x 0.10 mm I.D., 0.08 µm df 29503-U
20 m x 0.18 mm I.D., 0.14 µm df 29504-U
30 m x 0.25 mm I.D., 0.20 µm df 29505-U
60 m x 0.25 mm I.D., 0.20 µm df 29506-U
30 m x 0.32 mm I.D., 0.26 µm df 29508-U
60 m x 0.32 mm I.D., 0.26 µm df 29509-U


References

  1. Sidisky, L.M.; Stenerson, K.K.; Buchanan, M.D. Supleco SLB-IL60 Ionic Liquid GC Coumns: Unique Selectivity; Supelco Reporter 32.2: 29–31.
  2. Sidisky, L.M.; Stenerson, K.K.; Buchanan, M.D. Supleco SLB-IL60 Ionic Liquid GC Coumns: Improved Resolution; Supelco Reporter 33.1: 21–22.
  3. Sidisky, L.M.; Stenerson, K.K.; M.D. Buchanan, M.D. Supelco SLB-IL60 Ionic Liquid Columns: Better High Temperature Stability; Supelco Reporter Volume 33.2: 6-9.
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