Supelco SLB®-IL60 Ionic Liquid GC Columns: Stability to Loss of Carrier Gas Flow

By: Leonard M Sidisky, Katharine K Stenerson, Michael D Buchanan, Reporter US Volume 33.4

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 fifth of several Reporter articles which explore various aspects of this column[1-4].

Hydroxyl (-OH) functional groups are abundant in polyethylene glycol (PEG) stationary phases. These active moieties can be oxidized when exposed to low levels of moisture and/or oxygen, contributing to degradation of the phase. The rate of phase degradation is accelerated with elevated temperatures. These phenomena have a direct impact on the maximum temperature limits of commercially available PEG columns.

The SLB-IL60 column is stable to 300 °C for both programmed and isothermal use. Compared to PEG columns, it exhibits both lower FID bleed, and better high temperature stability. These features are possible because the structure of the ionic liquid stationary phase does not contain any hydroxyl groups. Complete specifications of SLB-IL60 columns are shown in Table 1.

Table 1. 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)


Carrier Gas Stop Flow Test
To illustrate the robust nature of the SLB-IL60 column, it was subjected to a brutal carrier gas stop-flow test. A polar column test mix was analyzed to establish initial chromatographic performance. This mix contains several analyte types, and can be used to measure key attributes of polar columns.

  • The normal alkanes (pentadecane, hexadecane, heptadecane, octadecane, and eicosane) are used to measure column efficiency
  • The alcohol (1-octanol) and ketone (2-octanone) are used to measure the presence of hydrogen-bonding sites (exposed silanols)
  • The acid/base pair (2,6-dimethylphenol/2,6-dimethylaniline) are used to measure the acid/base characteristic of the phase surface

The carrier gas flow was then turned off, and the oven heated to 250 °C. After 1 hour, carrier gas flow was re-established, followed by the analysis of the polar column test mix. This cycle was then repeated a second time. The degree that column performance changed was determined by comparing the resulting chromatography from the three polar column test mix runs, which are shown in Figure 1. No significant change in chromatographic performance was observed, even after the column was held at 250 °C for a total of 2 hours with no carrier gas flow. Peak shapes, absolute retention times, and relative retention times are virtually identical for the all three chromatograms. This is impressive.


Figure 1. Performance Before/After Stop Flow Test

CONDITIONS: column: SLB-IL60, 30 m × 0.25 mm I.D., 0.20 µm (29505-U); oven: 130 °C (25 min); inj. temp.: 250 °C; carrier gas: helium, 25 cm/sec; detector: FID, 250 °C; injection: 1 µL, 100:1 split; liner: 4 mm I.D., split/splitless type, single taper wool packed FocusLiner™ design; sample: polar column test mix (47302), 9 analytes, each at 500 µg/mL in dichloromethane


Conclusion
Columns based on polyethylene glycol phase chemistry are widely used for a variety of applications (such as solvents and FAMEs), but are limited to use below 260-280 °C oven temperature. The SLB-IL60 column is similar in selectivity to PEG columns, but can be used to 300 °C without degradation of chromatographic performance. This column also exhibits substantial robustness, able to withstand the temporary loss of carrier gas flow without damaging the stationary phase.

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
Polar Column Test Mix
500 µg/mL, dichloromethane, 1 x 2 mL 47302

Trademarks

  • SLB is a registered trademark of Sigma-Aldrich Co. LLC
  • Focusliner is a trademark of SGE Analytical Science Pty. Ltd.

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.
  4. Sidisky, L. M.; Stenerson K. K.; Buchanan, M. D. Supelco SLB-IL60 Ionic Liquid Columns: Lower FID Bleed; Supelco Reporter Volume 33.3: 30-31.
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