Use of total organic carbon analysis and Fourier-transform infrared spectroscopy to determine residues of cleaning agents on surfaces

Total organic carbon (TOC) analysis can be used in many cases as a nonspecific method of determining trace levels of organic residue on manufacturing equipment before and after cleaning. In this study, a swab sampling method followed by TOC analysis is used to determine organic residue levels associated with alkaline and acidic cleaning agents on a stainless steel surface. The alkaline cleaning agent was nonvolatile, resulting in favorable TOC analysis and validation. The acidic cleaning agent was very volatile, requiring more skilled sample handling and resulting in a more difficult validation. Fourier-transform infrared (FTIR) spectroscopy with a grazing-angle sample attachment can be used for direct surface measurements of cleaning-agent residues on a stainless steel surface. FTIR spectroscopic studies complement and support the TOC studies. One band chosen for each cleaning agent was monitored throughout the cleaning process