Hello all,
I am developing an LC–MS/MS method for N-nitroso tadalafil. Based on structure, I expected the [M+H]⁺ precursor around m/z 419, but in my scan I am seeing a strong signal at m/z 389.
Has anyone else observed m/z 389 for N-nitroso tadalafil?
Is this a valid precursor ion or could it be an in-source fragment/adduct?
Any insights or shared experience would be very helpful.
Hi.
if I may intervene, I see that community’s attention and interest is increasing in relation to Nitroso-compound. I am wondering if this comes from regulatories’ requests…
This topic is discussed in Analytical challenge for determination of instable standard of other N-nitroso structure
Regards
Hello,
The ion 389 that you are working is the nitroso-tadalafil molecule without the nitroso (NO) group. We had the same issue and after some testing (Scans, etc.) and discussions with the standard supplier we were able to find the the compound is unstable in the LC-MS/MS source (probably due the temperature, as we find out later in the method development) and could not find the ion 419 with enough intensity to work with. So we use also the 389.
However, if you work with 389 you must be able to separate the nitroso-tadalafil from tadalafil with enough resolution, as tadalafil as the ion 390 as [M+H]⁺ and can interfere with the 389 ion (with neutral form 389 or isotopic profiles).
Regarding the stability of the compound I already talk a little in the topic Analytical challenge for determination of instable standard of other N-nitroso structure.
Best Regards,
Daniel
Hi everyone, here is a link where you can find more strategies on how to mitigate in-source fragmentation in NDSRI analysis using LC-MS. I believe this resource will be valuable to the community:
Best regards,
Lucas Maciel