The control of the microcapsule wall by use of the Energy Dispersive X-ray Analysis

The energy dispersive X-ray analytical procedure (EDS) was applied to the control of the microcapsule coating. Ethylcellulose (EC) was the coating material. The microcapsule core was either sulfadiazine or salbutamol sulfate. As the sulfur atom is not contained in the ethylcellulose molecule but only in the drug molecules, clearly the EDS emission of sulfur can be merely considered the evidence of the microcapsule core. The results of the analysis show a decrease in the intensity of the EDS emission from the microcapsule core in respect to that from both the uncoated drug crystals and the physical mixtures of drug and EC. Furthermore, the emission intensity decreases as the wall thickness increases. The EDS analysis could be therefore useful for the technological control of the actual drug microencapsulation and the batch-to-batch reproductibility of the wall thickness.