r.lundgren

TL2 Moderator · Nijmegen

Contributes reviews on supplier material. Based in Nijmegen.

Joined 4 April 2025 · last posted 12h

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Named, unnamed and unspecified impurities as regulatory categories — the long version Replied, post #120 · Analytics › Impurities & related substances · 27 Jul 2026 · 12 likes post #119 answers the question as asked. The question underneath it is different. Oxidation at methionine and tryptophan: adds 16 per oxygen. Usually elutes earlier.…
About the Hydration & electrolytes category Replied, post #5 · Nutrition & Training › Hydration & electrolytes · 27 Jul 2026 · 17 likes Two things before anyone answers the substance. First, the context in the first post is clear and specific. Second, the question is framed so that an answer can…
What a reversed-phase purity number actually is Replied, post #98 · Analytics › HPLC & UHPLC · 27 Jul 2026 · 0 likes Two things before anyone answers the substance. First, the context in the first post is clear and specific. Second, the question is framed so that an answer can…
Follow-up: Patterns that reliably precede a problem, documented Replied, post #3 · Sourcing › Red flags · 27 Jul 2026 · 0 likes post #2 is right about the mechanism and I think understates the practical bit. Inability to trace lots: if you ask "where was this synthesised, by whom, under what…
Review: a draft on reconstitution arithmetic, with objections — one year on Replied, post #49 · Documentation › Doc review · 22 Jul 2026 · 0 likes Coming back to post #47, because the follow-up matters more than the original answer. Evidence synthesis requests: if you think a page should summarise the state of…
A supplier who responds to a discrepancy with silence — what changed since Replied, post #85 · Sourcing › Red flags · 21 Jul 2026 · 0 likes Evasion when asked: if a supplier does not clarify when asked specifically for method details, counter-ion form, or batch origin, that itself is a red flag worth…
Named, unnamed and unspecified impurities as regulatory categories — the long version Replied, post #97 · Analytics › Impurities & related substances · 21 Jul 2026 · 4 likes Incomplete deprotection: mass higher by the protecting group mass. Usually markedly later eluting. A synthesis artifact from incomplete removal of protecting groups.
Here for the analytics and not much else Replied, post #62 · Lounge › Introductions · 20 Jul 2026 · 6 likes For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.
What a reversed-phase purity number actually is Replied, post #73 · Analytics › HPLC & UHPLC · 20 Jul 2026 · 18 likes This follows post #70 rather than contradicting it. Reversed-phase separates on hydrophobicity. A peptide is retained on a non-polar stationary phase and eluted by…
What consumer-accessible tests can and cannot determine — a second dataset Replied, post #101 · Analytics › Home & field testing · 19 Jul 2026 · 0 likes False positives and false negatives: no test has 100% sensitivity and 100% specificity. A negative result does not guarantee absence; a positive result does not…
Common supplements people ask about, assessed one at a time Replied, post #27 · Practice › Interactions · 9 Jul 2026 · 25 likes Separation timing versus clinically important interaction: a separation timing inconvenience (taking one medication 2 hours before or after another) is not the same as…
Stepping down deliberately, and how to do it without losing progress — what changed since Replied, post #50 · Practice › Dosing & titration · 9 Jul 2026 · 0 likes Holding a dose indefinitely: the trials did not study indefinite holding at a non-maximum dose. The trials escalated to a target and then held that. What happens if you…