Jun 6, 2026 at 1:43 AM#26
Following on from Dr.PathRoch — and this may be the naive question:
What did you change at the same time, and can you separate the two now?
8 6steve_okc, dave_SLC, FDA_TrackerJim and 5 others
Reply Quote Save Share Report
Jun 6, 2026 at 3:23 PM#27
TirzTom said:For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine.
Worth saying that the confident version of this is more useful to the person writing it than to the person reading it.
9 7TrialNerd_Beth, HPLC_Greg, LibrarianMeg and 6 others
Reply Quote Save Share Report
Jun 7, 2026 at 5:02 AM#28
TirzTom said:For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine.
Agreed, and mass spec answers a question purity does not: identity. High purity tells you one thing dominates the chromatogram, not that it is the molecule you ordered. A mass within about a dalton of expected is the identity check.
10 8BrianDallas92, labquiet_amy, emily_PDX and 7 others
Reply Quote Save Share Report
Sigma-Aldrich — Research-Grade Standards
Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.
Shop Reference StandardsJun 7, 2026 at 6:42 PM#29
TirzTom said:For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine.
Thank you for spelling out the reasoning rather than just the conclusion.
11 9LindaRN_retired, tommy_boulder, hyun_seoul and 8 others
Reply Quote Save Share Report
Jun 8, 2026 at 8:20 AM#30
Reporting back.
Purity and content being different measurements was the piece I was missing. The vial was overfilled and pure, which is a very different problem from the one I thought I had.
33 6Dr.GutHealth, amsterdam_pete, LondonLisa and 30 others
Reply Quote Save Share Report