By Anonymous on Tuesday, July 29, 2003 - 10:16 pm:
i am developing a method of analysis for gatifloxacin which is quinoline derivatives and having closely related impurity structures .
i tried with all PH On reverse phase , that is ph 2.5,6.5,9.2
i fouund that at 6.5 ph my impurity seperation is maximum at other ph it mergers with the main peak .
i am using 10ml of trithyl amine in 1 litre of buffer and mobile phase composition is 80buffer and 20 actonitrile . my peaks are tailing too much even with xterra RP8 and with this much TEA what could be the reason and solution to this .
By Anonymous on Saturday, August 2, 2003 - 02:18 pm:
Maybe the tailing has another reason. What is the injection solvent? How much are you injecting?
By Anonymous on Sunday, August 3, 2003 - 10:17 pm:
Injection solvent is mobile phase A consist of a
80% buffer and 20% acetonitrile.
injection volume is very less its 10ul only . this can not be a reason .
By Anonymous on Monday, August 4, 2003 - 04:47 pm:
All of these things look OK: high buffer concentration, sample in mobile phase, small injection volume. The tailing should change with pH....
Does the retention change with pH?
By Anonymous on Tuesday, August 5, 2003 - 06:15 am:
Tailing changes with Ph in acidic ph it gives good peak shape but resolution with the impurities lost and other two impurity eluting after drug peak becoms broder so this ph is very much optimized ph.
so i need to know how i can reduce the tailing in present condition .
By Anonymous on Tuesday, August 5, 2003 - 04:19 pm:
Hmm... I suggest you try a SymmetryShield RP 8 or 18, instead of the XTerra RP8 column.
By Andreas Neumaier on Monday, August 11, 2003 - 12:59 am:
Try mobile phase with 90% water (with 0.5% 0.5M sulfuric acid) and 10% ACN on a C18 or Phenyl column.
Change % of ACN for pleasant RT.
(And use a column which is not contaminated with TEA.)