Moxifloxacin HCl was received from INDUS pharma Karachi, Pakistan and used as a working standard, Batch No. EL-03/L011/M/14138, Manufacturer, Enaltec Labs Chemistry, from India. The reading of the potency of Moxifloxacin HCl on anhydrous basis and their moisture content were taken from the certificate of analysis (CoA) provided by the vendor i.e., 99.81 % and 3.59 % respectively. Analytical grade reagents, potassium dihydrogen phosphate (≥99%.) and sodium hydroxide (≥97%.), were purchased from Merck KGaA, Germany.