Hi,
since I was around and saw your recent post marked urgent - until someone else can come up with better answers:
"Why HPLC is called as high precision?"
High Pressure/Performance Liquid Chromatography - it's just another name for Chromatography applied to instrumental analysis, the name that stuck was HPLC.
"why HPLC is called as high performance?"
I think the equipment manufacturers insist on 'Performance' in the name - 'performance' sells better than 'pressure'.