Study of particulate matter in carbenicillin disodium using scanning electron microscopy and microbeam x-ray spectrography.

A scanning electron microscopy membrane filtration study was conducted to determine the particulate contamination of samples of carbenicillin disodium which had been manufactured by bulk filling and by lyophilization. The bulk-filled product contained more contaminating particles than the lyophilized product. In both products, the number of particles increased logarithmically with decreasing particle size in the range measured (exceeding 0.1 micron). X-ray spectrographic analysis of particles larger than 0.5 micron revealed that the major particulate contaminates in both products were composed primarily of elements below atomic number 10. It is concluded that packaging of carbenicillin disodium by lyophilization of a solution results in significantly less submicrometer particulate contamination than packaging by sterile bulk filling of spray-dried powder.