Dry-Swabbing/Image Analysis Technique for the Pharmaceutical Equipment Cleaning Validation

This paper presents the development of a new technique using the dry-swabbing method for monitoring the contamination of pharmaceutical equipment. Black polyester wipes were used to improve the detection limit of the visual inspection. A standardized method of producing model impurity was used to produce known contamination of the model surface by a variety of compounds ranging from 0 to 500 μg.dm-2. The sample contaminations were dry swabbed and evaluated by measuring the intensity of contamination using the computer image analysis. The detected intensities of contamination were always proportional to the amount of the impurity applied. The dry-swabbing method has been proven to be at least by one order of magnitude more sensitive than mere visual check.