Can anyone help with an HPLC method development for the determination of SSD, as a stability indicator in an ageing trial.

Historically, have inherited a method running under the following conditions:-

HYPERSIL column 5u ODS 15cm x 4mm
Mobile phase 9:1 1% acetic acid:methanol (1ml/min)
Wavelength of detection 266nm
Injection size 20ul

The SSD is extracted from an emulsion using dilute ammonia soln. and then adjusted to mimic the mobile phase.

SSD recovery from the emulsion is intermittently low, 5-15% below the nominal expected value (1%)

Hope that somebody can help.

Thanks in advance.