Columns coated with bondable PEG and, even more so with traditional Carbowax 20M, deteriorate in the presence of oxygen. It has been necessary, therefore, to maintain an oxygen-free chromatographic system. To lower the costs of maintaining such a system and to improve the chromatographic properties of the PEG-type columns, we offer the oxygen-resistant BTR-CW phase type. BTR-CW is a polyethylene glycol (PEG) phase, similar to 007-CW phase, but which incorporates an anti-oxidant moiety to better withstand oxygen exposure and the resultant degradation. The BTR-CW also offers increased thermal stability and longer column lifetimes.