Residue for sanitizer

Does anyone had to do do residue analsis for sanitzers? We use isoporpyl alcohol and oxonia to sanitize the equipment. Due to high volatility of both products how can I do any testing to prove that that there is no residue. Hope someone can guide me in the right direction.

Does Isopropyl alcohol leaves any residue? what kind of % are you using? anywhere between 70% to 100% typically should not have any residue left on the surfaces. However you can use the ICH RS limits ( I am not sure it is class 3 solvent so must be 5000 PPM?)

we are using 70% isopropyl. I believed there should be no residue, however we have to prove it.
Thank you for reply.

Dear Beata,

In my opinion the most straightforward way to prove that the sanitizing agents are eliminated is with TOC. The proposed approach is to clean the equipment without sanitizing, and swabbing at the worst case locations, which in this case depend on the way the sanitizer is eliminated (e.g. worst case points would be the worst ventilated in case the sanitizer is allowed to evaporate, or the last points to dry in case the sanitizer is rinsed off with WFI). Once determined the normal background TOC leftover, the equipment is cleaned, sanitized, the sanitizer eliminated, and the swabbed again at the same locations. The difference in TOC, if any, is due to the sanitizer residue.

Best regards


Dear Mr Beata,

If you are using sanitizer(s) for product contact surfaces then you have to analyze the surfaces for the presence of the sanitizer residues irrespective of the fact the sanitizer being used is volatile or not. Two simple reasons for this are (a) safety of consumer (to ensure the product is safe for human use) and (b) Quality of Drug/Finished product (to ensure that the sanitizer residue doesn’t affect the quality of drug product). For this you need to prove that the amount of residue left-over is well below the Maximum permitted residue (or in other words MACO, calculated based on Acceptable Daily Intake value of the residue in concern) limit for the sanitizer &/or its components.

As far as I know, both the sanitizers are safe (provided below a certain limit) and easily removable. Isopropyl Alcohol as per ICH Topic Q 3 C is Class 3 Solvent (relatively safer). Oxonia (a product of Ecolab) contains Hydrogen Peroxide and Peroxyacetic acid. The sanitizer which could possibly leave residues on equipment surfaces is Oxonia (you need to look for traces of Hydrogen Peroxide on the surface). I am not sure that for testing these materials TOC will be a good idea. One can’t detect the presence of Hydrogen Peroxide using TOC as it doesn’t contain any organic carbon. Even for IPA the most commonly used method for analysis is GC not TOC. In this case the best way of proving that the residue content is well below acceptance limit is to (a) perform rinse sampling of the surface with purified water/WFI (both the materials are water soluble), and (b) analyze the collected samples with a suitable method for quantitation of residue. For analytical method you may use the methods specified in BP/USP or can ask respective supplier to provide a suitable testing method.