I ame working on a new lcms method for steroids in serum. method uses c18 uhplc column, 0.1 mM NH4F in water as A, 0.1 mM NH4F ijn methanol as B.gradient from 45 to 95 %B in 8 min. LC is an agilent 1290.
Every time at random the system gets glogged.sometimes tubing, sometimes solvent preheater, sometimes column. A filter is placed in sample pick-up. Water and methanol are also used on an other uhplc fir an other method without trouble.
Anyone has a sugrdtion what goes wrong here?