Unexpected peak in mass spec positive ion mode, reason?

Sanjeevan Rajendran @Sanjeevan-Rajendran

06 September 2023 0 8K Report

Recently we are getting strange peak at 8-9 min in LCMS. The peak showing up 50-60% of ACN in the mass spec positive ion mode (please see the attachments). However, the peak was invisible in PDA and negative ion mode of MS. After washing the system for couple of days the peak reduces but showing up again after few injection of samples. Is there are any possible contamination or fault of the instrument? Looking forward the experts opinion. Thank you.

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Science method

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