For cleaning validation purposes, the combination of swab sampling and the total organic carbon (TOC) test method provides a useful mechanism to monitor the cleanliness of equipment surfaces. The TOC test method is an ideal choice for monitoring carbon-containing residuals. Sample and test method validation "TOC Swabbing Method Validation" BV-000-BC-078-01, Bayer Healthcare, proved quantifiable recovery of albumin down to 25 microg. The validation characteristics included accuracy, repeatability and intermediate precision, specificity, linearity, assay range, detection and quantitation limit, and robustness.