Column bleed is minimal at 320 °C. Peak quality remains good for 5 to 6 months averaging 40 injections in a 24 hour period, 6 to 7 days per week. ”. — Kevin Walkup, Specialized Assays, Inc., USA. “ The Zebron ZB-5 column has proven to be a winner. It produces high resolution chromatography in a very reliable manner.