Quality assurance residual solvents

During the coating process, controlled conditions and coating weight should be monitored periodically by the operators to assure that the environment is appropriate to reduce the content of residual solvents and to attain proper curing. The thickness of the casting solution layer should be controlled and used to assess the final quality of the systems manufactured. 

There are potential quality assurance problems with the analysis of PCAs at trace levels in environmental samples because of their use in some consumer products like PVC or paints, and in metal cutting oils. Standard precautions used for the analysis of PCBs and other organochlorines such as use of glass distilled solvents, high temperature heating of filters, glassware, and sodium sulfate, and minimal use of plastics, should also minimize contamination by PCAs. This contamination is potentially more difficult to control under field conditions where PCAs maybe incorporated into outdoor paints and sealants or may be residues on or in sampling equipment. 

The tools presented throughout this section are intended to be used in all the steps of the scale-up to assure the production of powders with the desired quality, viz. particle size, particle morphology, and level of residual solvents. This enhanced understanding and mechanistic thinking, in line with the quality by design (QbD) initiative, will support the establishment of ample design spaces that are both unit and scale independent. 

There should be some periodic testing after cleaning, to assure that the surface has been cleaned to the validated level. One common method is the analysis of the final rinse water or solvent for the presence of the substance last used in that piece of equipment In some cases, visual inspections may be appropriate. A specific analytical method for the determination of residual substances may not always be available. The need for an analytical method would be based on the potential adverse effect on product quality, performance or safety. In case of a safety issue, there should always be a specific analytical determination for a residual substance. 

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