[Selective membrane electrode for the determination of ammonia released from rubber caps of containers for parenteral...

It is dealt with an ammonia-selective membrane electrode for the quantitative determination of volatile amines and ammonia released from rubber caps of containers for parenteral solutions. The optimal measurement parameters were determined. It was demonstrated that the electrode is well suited for ammonia determinations in the range of 10(-6) to 10(-1) mol/l. As this method requires but little time and yields accurate results, it will be helpful in laboratories with heavy routine workloads. Fifteen different caps based on natural rubber, chlorobutyl rubber or bromobutyl rubber were tested for their usefulness as packaging materials for drugs. According to the amounts of released ammonia, the caps were classified into three categories.