What is system suitability in hplc system how can we decide to take perticular substance as a system suitability

Could you reformulate your question? I don't understand it at all...

Are you asking for the stationary phase in an HPLC column? These are usually uniform porous silica particles of diameter 1 micro metre, and with surface pores of 1 nano metre to increase the surface area.

You can also check the link:
http://pubs.acs.org/subscribe/journa...ml/09dong.html