Use of back-scattered electron imaging as a tool for examining matrix structure of calcium pectinate.

The internal structure of pharmaceutical solid dosage forms is commonly revealed by secondary electron imaging using standard scanning electron microscopy (SEM) technique. In this work we propose a back-scattered electron imaging (BEI) as a new tool for examining the matrix structure of calcium pectinate beads. Imaging samples with back-scattered electrons in the SEM is based on material or atomic number contrast. High atomic number elements, such as calcium, reflect more electrons and appear bright on electron micrographs. The BEI-SEM images of calcium pectinate matrix beads clearly showed net-like structure of calcium pectinate and uniform distribution of drug particles. The matrix compositions were confirmed by energy dispersive analyzer. The result demonstrates the advantageous of BEI for examining the matrix structure of calcium pectinate.