Assessment of possible disruptive effects of residues from cleaning agents on medical devices after cleaning on protein assays
H. Hubert*, L. Schnieder
The most important analyte used to verify the cleanliness of a medical device after a cleaning process is protein [1, 2]. There are a variety of different Assays to test for protein, the most commonly used Assays are based on ortho-phthalaldehyde (OPA) and bicinchoninic acid (BCA) . In this study 42 different cleaning detergents from 14 different manufacturers were tested for their potential to influence the output of these Assays. Serial dilutions of these detergents ranging from 1 % to 0.001 % were tested. The matrix 1 % alkalized (pH 11.0) sodium dodecyl sulfate (SDS) solution was chosen, as this is one of the suggested and established extraction fluids for medical devices .
Five of these tested detergents showed a high potential risk of affecting the performance of the OPA Assay. The results were over 100 μg/ml expressed as bovine serum albumin (BSA) equivalent at a concentration of 0.031 %. 17 detergents showed a medium potential risk with results higher than 10 µg/ml at a concentration of 0.25 %, thus only influencing the signal at a comparatively high concentration. 20 detergents were not significantly affecting the OPA Assay (results < 10 µg/ ml at a concentration of 0.25 %).
For the BCA Assay, only one detergent showed a high potential risk with a result of over 100 μg/ml at a concentration of 0.031%. Five detergents showed a medium potential risk with results higher than 10 µg/ml at a concentration of 0.25%. 36 detergents were not significantly affecting the BCA Assay (results < 10 µg/ml at a concentration of 0.25%).
Overall, the OPA Assay was more susceptible to interferences from cleaning detergents than the BCA Assay. With the approach described it is possible to identify the risk if an Assay might be impaired by residuals of the cleaning detergent after a cleaning process.
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