Chromatography Forum

I developed an LC-MS/MS method for an amino acid using ethanol/ water 20/80 @ 1mL/min isocratic, reverse phase mobile phase and a 250 x 4.6mm Chirobiotic TAG column. Chiral separation was initially good but resolution has now been lost!! The endogenous L-enantiomer from plasma is swamping the D-enantiomer, which i am trying to quantify. The amino acid has pka's spanning the entire range, buffering likely to help?

Any ideas would be much appreciated.

Thanks,

Chris.