Mega bore columns

The internal diameter of columns used in capillary GC varies from 0.1 mm (microbore capillary) via 0.15 and 0.18 mm (narrow-bore) and the standard columns with 0.25 (normal) and 0.32 mm (wide-bore) to 0.53 mm. For the direct coupling with mass spectrometers, in practice only the columns up to 0.32 mm internal diameter are used. Mega-bore columns with a diameter of 0.53 mm (halfmil) are mainly used for pre-columns (retention gap, deactivated, no stationary phase) or to replace packed 1/8" steel columns in specially engineered GC instruments. 

Figure 4.30 Dual mega-bore capillary column configuration used to study the isolation and recovery of organophosphorus pesticides.

With this purpose, these oils were analyzed using Shimadzu GC 14B gas chromatograph equipped with a Mega Bore DB-WAX P / N125-7032 column (30 mx 0.53 mm id x 1 micron film thickness) and a FID detector. 

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