Differences in Physical Form of Nitrosamine Reference Standards: USP vs. Other Suppliers

Confirmatory Testing & Analytical Challenges
1

Most USP reference standards for nitrosamines are supplied in liquid form, whereas other suppliers are predominantly provided as powder. Could you please advise if there is a specific rationale for USP offering these standards in liquid form? For instance, is this related to improved stability or reduced susceptibility to degradation in the liquid state? Is there any other reason that I may not be aware of? Could the reference standards from other suppliers be considered reliable? For reference, I have included example links to the relevant USP standards below.

Thank you for your time and consideration. I look forward to your guidance.

USP Standards : [N-Nitroso Sertraline Solution (1 mL (1 mg/mL)) (N-((1S,4S)-4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydronaphthalen-1-yl)-N-methylnitrous amide)] - CAS [3006789-98-3]

[N-Nitroso Moxifloxacin Solution (1 mL (1 mg/mL)) (1-Cyclopropyl-6-fluoro-8-methoxy-7-((4aS,7aS)-1-nitrosooctahydro-6H-pyrrolo[3,4-b]pyridin-6-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid)] - CAS [N/A]

Other suppliers :

Product Page

N-Nitroso Sertraline | CAS No- NA | Simson Pharma Limited