One area my company and one of our CMOs need help with is passivation. One of our CMOs needs to perform passivation with a nitric acid solution to help with a yield issue and impurities. However, they have stated that their process cant ensure low enough levels of nitric acid to a ppb level. Does anyone have experience with this? The company said passivation with citric acid is not adequate but they are concerned that low levels of nitric acid could lead to nitrosamines with these materials as at least one contains a piperidine ring in its structure. Does anyone have recommendations for a company who we can use to contract the passivation and cleaning work?
Interesting question - we had an API where the reactor needed pacification every 5 batches to present loss of yield. If citric acid does not work you have several options. First check experimentally if the nitrite residue is sufficient to give problems after proper rinsing. If there is still a problem, maybe you could switch to a non-SS reactor and a final but poor oprion is to see whether phosphoric acid works–there are plenty of comments that it is not so great as a pacifier but it used to be used with some success
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Thank you so much! Your response is very timely. We are meeting on it tomorrow. I will reach out if there are any other questions.
The best bet is to prove the absence of available nitrite after pacification but you will need pretty sensitive testing to give you confidence
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This is not a process I’m familiar with. So, forgive me, but maybe you can do some water washes and use a purge factor.
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