A retention gap 1 m x 0,32 mm i.d. connected to a CP-WAX 57 CB column 50 m x 0,32 mm i.d. 0,2 µm film thickness (stabilised polyethylene glycol) followed by a Carbowax 400 column 50 m x 0,32 mm i.d. 0,2 µm film thickness. (Columns are connected using press-fit connectors.)