Clindamycin phosphate CP impurity ⅰ; Methyl 7- chloro -6,7,8- tri-deoxy-6-[[(2S, 4R)-4- ethyl -1- methylpyrrolidine -2- yl] carbonyl] amino ]-2-O- phosphine -1- thio -L- threonine -α-D- galactose-octa. Clindamycin phosphate EP impurity b; Clindamycin b phosphate