The present invention provides a method for designing a ferric pyrophosphate citrate complex composition containing pyrophosphate, citrate, ferric, sodium, and sulfate ions and calculating and adjusting each salt needed based on a choice of salts that contain the above ions and a desired concentration of each ion in the final product. The present invention also provides a process for preparing a pharmaceutical dosage form of ferric pyrophosphate citrate complex composition in liquid form which is ready to be administrated to patients in need and which maintains the mass balance of ion sources throughout the process.