在要求准确调节生物碱溶液pH值时,应怎样计算酸的用量? 答:生物碱在偏酸性溶液中较稳定。将其盐制成注射液时,常须加酸调节其pH值,有时还加入氯化钠等附加剂,因此溶液中的离子强度较大,明显影响氢离子的活度。现介绍一种以氢离子活度系数为基础的加酸量计算法,以1%盐酸普鲁卡因液(含0.64%NaCl)为例说明如下。 When asked to accurately adjust the pH of alkaloid solution, how to calculate the amount of acid? A: alkaloids in acidic solution is more stable. When the salt is made into the injection, it is often necessary to add acid to adjust its pH, and sometimes add sodium chloride and other additives, so the ionic strength of the solution is larger, significantly affecting the activity of hydrogen ions. A hydrogenation activity coefficient based on the amount of acid calculation is introduced to 1% procaine hydrochloride solution (containing 0.64% NaCl) as an example as follows.