Answer to Question #38993 in Physical Chemistry for Massi

Question

Hi, I have some samples with a volume about 2ml kept in -80 ready to ship for the NMR analysis. They contain some chemicals such as pyruvate, Malate, ATP, succinate,etc. I have forgotten to add 0.3mM creatinine which is used as a standard. As I haven't sent them yet, I wonder if i still can add the creatinine into my samples without thawing them. Because I just feel if I defrost my samples, some chemicals might get damaged. I would appreciate if could help me with this issue as soon as possible. Thanks

Answer 1

Freezing at -80⁰C until analysis is a good choice for NMR samples to avoid degradation. Biochemical constituents of your specimen are sufficiently stable. Thus, single freeze-thaw cycle will not affect results obtained by NMR spectroscopy.