The non-polar 007-1 dimethylpolysiloxane phase, which separates compounds according to boiling point, is probably the most frequently used phase type in GC.

 

Aluminum-clad fused silica columns offer the same inert internal fused silica surface, but with an outer layer of aluminum instead of the standard polyimide normally found on GC capillary columns

 

The 007-5 phase is a (5% phenyl) methylpolysiloxane polymer. Like the 007-1dimethylpolysiloxane phase, the 007-5 phase is a widely used general purpose GC phase ideal for a broad range of applications. The presence of the phenyl groups provides induced dipole interactions leading to degrees of increased retention for aromatic solutes. A 5% phenyl substitution causes a nominal increase in polarity; yet the 007-5 phase displays the attributes of a non-polar phase.

 

Aluminum-clad fused silica columns offer the same inert internal fused silica surface, but with an outer layer of aluminum instead of the standard polyimide normally found on GC capillary columns. Polyimide has an upper temperature limit of approximately 390°C before degradation occurs. By utilizing an aluminum outer layer, GC columns can extend the operating temperature range upwards to 440-450°C which is useful for high molecular weight applications.

 

Traditional polysiloxane-type GC stationary phases degrade at elevated temperatures. The degradation process is well documented and consists of the thermal rearrangement of the siloxane backbone to produce cyclic groups. These groups are volatile and elute from the column as column 'bleed'. The silphenylene units (Fig. 1) within the 007-5MS backbone act as heat sinks and limit the formation of the cyclic groups normally associated with polysiloxane degradation.

 

007-10 and 007-20 (10% and 20% phenyl substitution, respectively) are the Quadrex designations of phenyldimethylpolysiloxane phases. The phenyl substitutions contribute to the "induced dipole" selectivity of these phases.

 

The 007-1301 is a (6% cyanopropylphenyl) methylpolysiloxane phase. Overall, 007-1301 is a low polarity phase which exhibits excellent thermal stability. The cyanopropyl (permanent dipole) and the phenyl (polarizable) substituents provide a specific selectivity for polar and polarizable compounds.

 

007-608, 007-624, and 007-502 offer three variations of cyanopropylphenyl substitutions on a methylpolysiloxane backbone.

 

007-35 is the Quadrex designation for a (35% phenyl) dimethylpolysiloxane phase. This phase is a compromise between 007-20 and 007-17 in phenyl content.

 

007-1701 is a (14% cyanopropylphenyl) methylpolysiloxane phase. The cyanopropyl functional groups provide a permanent dipole selectivity different from the induced dipole interactions of the phenyl groups. The overall "polarity" of this phase remains nominal when compared to the more highly cyanopropyl substituted phases such as 007-225 and 007-23.

 

007-17 is a 50% phenyl methylpolysiloxane phase. The presence of the 50% phenyl groups increases the overall "polarity" of the phase and enhances the selectivity of induced dipole interactions resulting in greater retention of aromatic solutes.

 

The 007-65HT and 400-65HT phases represent a (65% phenyl) methylpolysiloxane phase composition. They are a companion phase to the 007-17 (50% phenyl methylpolysiloxane), but the additional 15% phenyl substitution provides greater selectivity toward compounds exhibiting induced dipole effects.

 

007-225 is the Quadrex designation for a 50% cyanopropylphenyl methylpolysiloxane. This phase possesses both permanent dipole interactions (nitrile) as well as induced dipole (phenyl) and dispersion interactions. It has unique selectivity for derivitized compounds such as fatty acids and carbohydrates. Non-volatile residues can be rinsed from the column to restore column performance.

 

007-CW and BTR-CW are the Quadrex designations for an ethylene glycol/siloxane copolymer. This polymer can be used to separate compounds at temperatures not normally associated with polyethylene glycol (PEG, CarbowaxTM) phases. Both the lower and upper temperature limits of traditional Carbowax type columns are extended with this phase.

 

007-FFAP is a nitroterephthalic acid modified polyethylene glycol (PEG) polymer. This bonded acidic phase is ideal for the analysis of aqueous solutions of free fatty acids as well as fatty acid methyl esters. As with the 007-CW (and BTR-CW) polyethylene glycol phases, 007-FFAP is not recommended for the analysis of silylating reagents.

 

The 007-23 is a (78% cyanopropyl) methylpolysiloxane and is our most polar phase type. The strong permanent dipole interactions of this phase with unsaturated compounds yields separations according to geometric configurations of the double bonds. The 007-23 phase is ideal for the separation of cis/trans isomers of fatty acid methyl esters (FAMEs) as well as the isomers of dioxins and furans.

 

The analysis of permanent gases is an important application in the petrochemical industry. Quadrex offers the PLT-5A molecular sieve PLOT capillary column as a replacement for the traditional packed molecular sieve column. A capillary PLOT column offers the advantage of a faster turn-around time between analyses as well as the added benefit of faster regeneration of the adsorbent layer.