In our case, I confirm that it is very difficult discriminate a “fake” N-nitroso Torasemide standard (MW 377.46) from the hypotetical N-nitroso Torasemide (MW 377.42). We believe that the supplier made an honest mistake.
However the NMR confirmed that the structure does not correspond to the hypotetical N-nitroso Torasemide.
We will evaluate other suppliers, but we believe that no one obtained the correct substance.
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Did you use 1H-15N HSQC as 2D NMR?
dear ccdw,
first of all, happy new year 
regarding the ‘‘fake’’ N-nitrosoticagrelor, we did not performed any NMR studies in our edge. All the information came from our API manufacturers. In their technical assessments, several NMR technics have been applied.
Among them, 1H-15N HSQC and 1H-15N HMBC experiments were performed.
have a nice day
Thanks, I share the opinion that these are the go-to 2D NMR methods for these cases.
I had to use it a few times as well in such cases, but to my surprise initially not all NMR facilities had these type of measurements pretested to offer as services.
Best wishes.
Hallo to the team,
please let me bring back again the issue of N-nitrosotorasemide.
Is anyone in this group that had purchased a ‘‘real’’ reference standard of it finally? The last one we received was ‘‘faked’’ and had similar issues with the case of paliog
Now we received a question/request from a client for confirmatory tests based on the existence of relevant reference standard in the market!!
thank you
Christos
Yes, during stability of the API there is chances of formation and leads to impact on during product as well.
Multiple times basis of theoretical data, impurity can be possible whereas practically synthesis of impurity doesn’t found success.
Dear Shirish,
how do you know that it appears during stability?
Do you have a method analysis for this?
And if yes, do you have a ref. standard of N-nitrosotorasemide?
thanks
Christos
All our accountable suppliers have agreed that N-nitrosotorasemide is not obtainable as a standard. Their synthesis experiments did not yield a reliable molecule to be used as an analytical standard.
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