To write in brief and precise. you may consult the college labs for undergraduate students of Pharmacy or even post graduate students of Pharmacy. They have regular lab courses on HPLC analysis.
I believe you can do that in the following laboratories in Nigeria:
The Analytical laboratory of the Federal Institute of Industrial Research, (FIIRO-ANALAB) in Oshodi, Lagos state and the NAFDAC Central Laboratory Complex in Oshodi , Lagos state.