Hemoglobin assay for validation and quality control of medical device reprocessing. 
Hemoglobin (Hb) is an important analyte in medicine, forensics, and research.  One area of crucial need for real-world Hb quantitation is the validation and quality control (QC) of reprocessed medical device cleaning.  Here, we show how a microplate reader and colorimetric blood test strips can be used to quantitate nanogram (ng) quantities of Hb in a 1-min assay.  The assay had a linear range of 0-50 ng (0-370 ng on a log scale) for Hb, with a limit of detection (LOD) of 3.3 ng, which was ∼500-fold more sensitive than the micro-BCA reagent (LOD = 1.6 μg) and on the same order of magnitude as detection of labeled Hb with fluorescence (LOD = 1.9 ng).  For validation of medical device cleaning, the assay was specific for Hb in the presence of artificial test soil and was unaffected by interferences from common cleaning reagents at 10 ppm.  Lubricant and sodium dodecyl sulfate did not significantly affect the assay at 10 ppm but affected the assay at 1 % g/g. The method showed 100 % recovery of hemoglobin in extracted soils, with extraction from silicone having the greatest variability in recovery, while Teflon and stainless steel had <10 % RSD.  The assay makes it possible for medical device companies and health-care providers to obtain crucially needed information on the cleanliness of reused devices.