Calibration of the instrument shall be done using a reference standard of potassium hydrogen phthalate (KHP). A point calibration curve is generated by using different concentrations of potassium hydrogen phthalate. Weigh accurately 0.2125g of KHP (equivalent to 100mg of carbon in KHP) and dissolve in 100ml of water. If you need more information about contact 4D-Technologies they are the best laboratory equipment suppliers in Pakistan