Capillary GC Columns for GC x GC

GCxGC is one of the fastest growing areas in analytical chemistry due to its ability to resolve a large number of compounds, even in the most complex samples. No other chromatographic technique can match the level of detail it provides. Common detectors, including MS, can be used. It employs two columns in series, separated by a modulator. The role of the modulator is to collect fractions from the first column (often called the primary column, first dimension column, or ¹D column) and focus them onto the second column (often called the secondary column, second dimension column, or ²D column). First dimension columns tend to be 30 m x 0.25 mm I.D., whereas second dimension columns tend to be short, cut down lengths of stock columns (0.10 or 0.18 mm I.D. for non-MS detectors, and 0.18 or 0.25 mm I.D. for MS detectors).

One key to the successful operation of GCxGC is that the two columns must have orthogonal selectivity, that is, they must utilize different retention mechanisms. The more different (more orthogonal), the better the overall performance will be. We offer columns for three column selection strategies to achieve orthogonal selectivity:

• Non-polar to polar strategy
• Polar to non-polar strategy
• High resolution polar to non-polar strategy

Non-polar to polar

Analytes are separated on a non-polar column in the first dimension, and on an intermediate polar, polar, highly polar, or extremely polar column in the second dimension. This traditional strategy is commonly used.

Individual first dimension

Non-polar GC columns are made with the least selective GC stationary phases. Interactions are primarily dispersive (van der Waals forces). Phases with phenyl functional groups can also undergo a moderate amount of π-π interactions. Elution order generally follows the boiling points of the analytes. Column choices (from least to most polar) are:

• SLB^®-1ms, non-polar, 100% methyl phase, temperature limits -60 °C to 340 °C (isothermal) and 360 °C (programmed)
• SLB^®-5ms, non-polar, 5% phenyl phase, temperature limits -60 °C to 340 °C (isothermal) and 360 °C (programmed)

Individual second dimension

Intermediate polar, polar, highly polar, and extremely polar GC columns are made with very selective GC stationary phases. These include polyethylene glycol, ionic liquids, and polysiloxane polymers with cyanopropyl functional groups. They are commonly used to analyze polar compounds (contain Br, Cl, F, N, O, P, and/or S atoms in addition to C and H atoms) and/or polarizable compounds (such as alkenes, alkynes, and aromatic hydrocarbons) that contain some double and/or triple bonds between carbon atoms. Dispersive (van der Waals forces), π-π, dipole-dipole, and dipole-induced dipole interactions are all strong with these columns. Moderate amounts of hydrogen bonding and basic interactions are also possible. Elution order is determined by the overall effects of all possible interactions.

Any of these 0.10 mm I.D. or 0.18 mm I.D. columns can be cut down to the desired length. Choices (from least polar to most polar) are:

• SLB^®-35ms, intermediate polar, 35% phenyl phase, temperature limits ambient to 350 °C (isothermal) and 360 °C (programmed)
• SLB^®-IL59, polar, ionic liquid phase, temperature limits subambient to 300 °C (isothermal or programmed)
• SLB^®-IL60, polar, ionic liquid phase, temperature limits subambient to 300 °C (isothermal or programmed)
• SLB^®-IL76, highly polar, ionic liquid phase, temperature limits subambiant to 270 °C (isothermal or programmed)
• SLB^®-IL82, highly polar, ionic liquid phase, temperature limits 50 °C to 270 °C (isothermal or programmed)
• SLB^®-IL111, extremely polar, ionic liquid phase, temperature limits 50 °C to 270 °C (isothermal or programmed)

Standards Standard mixes can be used to conveniently establish retention time markers. Included below are several n-alkane, PAH, and BTEX mixes.

Polar to non-polar strategy

Analytes are separated on an intermediate polar, polar, highly polar, or extremely polar column in the first dimension, and on a non-polar column in the second dimension. This strategy is opposite of the first strategy.

Individual First dimension

Intermediate polar, polar, highly polar, and extremely polar GC columns are made with very selective GC stationary phases. These include polyethylene glycol, ionic liquids, and polysiloxane polymers with cyanopropyl functional groups. They are commonly used to analyze polar compounds (contain Br, Cl, F, N, O, P, and/or S atoms in addition to C and H atoms) and/or polarizable compounds (such as alkenes, alkynes, and aromatic hydrocarbons) that contain some double and/or triple bonds between carbon atoms. Dispersive (van der Waals forces), π-π, dipole-dipole, and dipole-induced dipole interactions are all strong with these columns. Moderate amounts of hydrogen bonding and basic interactions are also possible. Elution order is determined by the overall effects of all possible interactions.

Column choices (from least polar to most polar) are:

• SLB^®-35ms, intermediate polar, 35% phenyl phase, temperature limits ambient to 350 °C (isothermal) and 360 °C (programmed)
• SUPELCOWAX^® 10, polar, polyethylene glycol phase, temperature limits 35 °C to 280 °C (isothermal or programmed)
• SLB^®-IL59, polar, ionic liquid phase, temperature limits subambient to 300 °C (isothermal or programmed)
• SLB^®-IL60, polar, ionic liquid phase, temperature limits 35 °C to 300 °C (isothermal or programmed)
• SLB^®-IL76, highly polar, ionic liquid phase, temperature limits subambient to 270 °C (isothermal or programmed)
• SLB^®-IL82, highly polar, ionic liquid phase, temperature limits 50 °C to 270 °C (isothermal or programmed)
• SLB^®-IL111, extremely polar, ionic liquid phase, temperature limits 50 °C to 270 °C (isothermal or programmed)

Individual Second dimension

Non-polar GC columns are made with the least selective GC stationary phases. Interactions are primarily dispersive (van der Waals forces). Phases with phenyl functional groups can also undergo a moderate amount of π-π interactions. Elution order generally follows the boiling points of the analytes.

Any of these 0.10 mm I.D. or 0.18 mm I.D. columns can be cut down to the desired length. Choices (from least polar to most polar) are:

• SLB^®-1ms, non-polar, 100% methyl phase, temperature limits -60 °C to 340 °C (isothermal) and 360 °C (programmed)
• SLB^®-5ms, non-polar, 5% phenyl phase, temperature limits -60 °C to 340 °C (isothermal) and 360 °C (programmed)

Standards

Standard mixes can be used to conveniently establish retention time markers. Included below are several saturated FAME and cis/trans FAME isomer mixes.

High resolution polar to non-polar strategy

Analytes are separated on a long (100 m or 200 m) highly polar or extremely polar column in the first dimension, and on a non-polar column in the second dimension. This strategy is very useful for some of the most difficult separations, such as resolution of individual cis/trans FAME isomers.

Individual First dimension

Polar, highly polar, and extremely polar GC columns are made with very selective GC stationary phases. These include polyethylene glycol, ionic liquids, and polysiloxane polymers with cyanopropyl functional groups. They are commonly used to analyze polar compounds (contain Br, Cl, F, N, O, P, and/or S atoms in addition to C and H atoms) and/or polarizable compounds (such as alkenes, alkynes, and aromatic hydrocarbons) that contain some double and/or triple bonds between carbon atoms. Dispersive (van der Waals forces), p-p, dipole-dipole, and dipole-induced dipole interactions are all strong with these columns. Moderate amounts of hydrogen bonding and basic interactions are also possible. Elution order is determined by the overall effects of all possible interactions.

Column choices (from least polar to most polar) are:

• SUPELCOWAX^® 10, polar, polyethylene glycol phase, temperature limits 35 °C to 280 °C (isothermal or programmed)
• SP^®-2560, highly polar, cyanopropyl siloxane phase, temperature limits subambient to 250 °C (isothermal or programmed)
• SLB^®-IL111, extremely polar, ionic liquid phase, temperature limits 50 °C to 270 °C (isothermal or programmed)

Standards

Standard mixes can be used to conveniently establish retention time markers. Included below are several saturated FAME and cis/trans FAME isomer mixes.