please tell me a bit about carbon loading of a hplc column...how does it affects the analysis etc.
thank u

It makes the analysis different. Carbon loading alone is not the important part, since different packings have different surface areas and pore volumes. For the same pore volume, a larger carbon content creates more reversed-phase retention. For the same carbon content, a packing with a larger pore volume creates less retention than a packing with a small pore volume.
You should look for surface coverage, in micromoles per squaremeter. This tells you how well the surface is covered. This is a better measure for the nature of the packing than the carbon content.