2. unvolatile acid(fixed acid): (50-100mmol/d) Uric acid, phosphoric acid(H3PO4)and sulfuric acid (H2S04)are the products in the metabolic process of proteins and nuclear acids Lactic acid and ketonic bodies(B-hydroxybutyric acid and acetoacetic acid) can be formed from the metabolic process of carbohydrate and fat as intermediate proaucts, when the oxygen supply is not sufficiency Exogenous acid( food and drug s Excretion through kidney2. unvolatile acid (fixed acid) ： (50-100mmol/d) Uric acid, phosphoric acid (H3PO4) and sulfuric acid (H2SO4) are the products in the metabolic process of proteins and nuclear acids. Lactic acid and ketonic bodies (β-hydroxybutyric acid and acetoacetic acid) can be formed from the metabolic process of carbohydrate and fat as intermediate products, when the oxygen supply is not sufficiency. Exogenous acid(food and drug)： Excretion through kidney