Ageing of columns of homogeneous mixed stationary phases in gas chromatography.

: Chromatographic columns of homogeneous mixed phase prepared with squalane and polyethylene glycol 1540 have been subjected to an ageing process of about 1700 hours at 100 degrees C followed by a similar period of time at 120 degrees C. Little change is observed at the lower temperature, while at 120 degrees C, a selective loss of the most volatile component of the mixture seems to occur, producing changes in the values of the retention indices obtained.