The goal is to validate an LOQ of 0.025% of a nominal concentration of 0.25 mg/ml. The compound is an oglionucleotide. A is a phosphate buffer at pH 7.9. B is A + 1.25M NH4Cl. Both A and B contain 10% ACN. % recovery is ~65% on a good day. I need it to be at least 80%.
I suspect that NH4Cl is not a strong enough salt for trace analyte concentrations. Any one out here have any ideas?