[Lab] GL Biochem raw material vs a reseller vial of nominally the same compound
Ran these on the same day, same method, same column, injections back to back. One is GL Biochem raw material, one is a reseller vial of nominally the same compound and nominally the same origin. Sample Main peak Largest single impurity Impurities >0.1% GL Biochem raw 99.3% 0.31% 3 Reseller vial 98.6% 0.74% 6 0.7…
the largest-single-impurity number is criminally under-reported. a 98.6% that is one 1.2% impurity is a different molecule situation to a 98.6% spread across eight small peaks.
yes and neither of those two vials is the bad case. i have seen a 97.9% that was basically one enormous shoulder and that one worried me a lot more than a 96 with a clean profile.
a shoulder that big is usually a des-amido form or an epimer and the integration decision on where to cut it changes your number by half a point on its own.
which is the actual source of most inter-lab disagreement, not instrument quality. two analysts drawing the baseline differently on the same trace.
i would love to see a round-robin on this. one trace, twenty people integrating it, publish the spread.
Post the raw trace and I will organise it. That would be a genuinely useful piece of community work.