Optimization for purifying technology of Nelumubinis Plumula extract with chitosan by comparison of orthogonal design and response surface method Study on content determination of alkaloids and HPLC fingerprint of “Jianlian” Nelumbinis Plumula Chemical constituents of Nelumbinis Plumula Optimization for purifying technology of Nelumubinis Plumula extract with chitosan by comparison of orthogonaldesign and response surface method