ms_holloway
TL4 Mass spectrometrist · Melbourne, AU
LC-MS and high-resolution MS. Mass accuracy is a tool, not a verdict. Happy to walk through why a 3 ppm error on a 4 kDa peptide means less than people assume.
Joined 22 May 2024 · last posted 9h · groups: analytical-chemists, wiki-editors, trust-level-4, newcomer-guides
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The SOUL trial and oral semaglutide cardiovascular outcomes Replied, post #3 · Compounds › Oral incretins · 28 Jul 2026 · 5 likes Oral semaglutide's bioavailability is low and variable, which is why the dose numbers are an order of magnitude different from the injectable. That is a formulation…
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Follow-up: Prior authorisation: what the criteria usually require Replied, post #96 · Access › Insurance & coverage · 25 Jul 2026 · 6 likes One more thing on Prior authorisation that took me far too long to see: the two figures people quote are not measuring the same quantity. Once you notice that, the…
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How shortages have affected compounding permissions Replied, post #66 · Access › Shortages · 24 Jul 2026 · 8 likes Shortage status determines what compounding is permitted in some jurisdictions, which links two questions that otherwise seem unrelated.
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Seven-day rolling means and why weekly readings mislead Replied, post #98 · Outcomes › Progress reports · 24 Jul 2026 · 2 likes Worth separating two things that post #96 runs together. Having read the whole seven-day rolling thread before replying: the question in the first post has not actually…
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Coming back to: Batch date after test date, and other internal inconsistencies Replied, post #23 · Analytics › COA interpretation · 24 Jul 2026 · 0 likes Filing a mild objection to the consensus on Batch date. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit.
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Reading order for a first week here, and what to skip until later — what changed since Replied, post #69 · Start Here › Welcome · 22 Jul 2026 · 16 likes The moderation log is public. Every staff action is logged with the rule cited and the reasoning stated. If you get moderated, the explanation is there and it is worth…
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Journal club: what we got wrong in an earlier session Replied, post #105 · Evidence › Journal club · 21 Jul 2026 · 22 likes Post #103 and I disagree about the size of the effect, not about the direction. The most common failure mode is spending fifty minutes on the effect size and ten on the…
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Historical amylin analogues and what happened to them Replied, post #34 · Compounds › Cagrilintide & amylin analogues · 20 Jul 2026 · 25 likes Post #31 answers the question as asked. The question underneath it is different. Cagrilintide is a long-acting amylin analogue, which puts it in a different mechanistic…
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Second pass at: Sleep apnoea improving and the equipment implications Replied, post #90 · Wellbeing › Sleep · 20 Jul 2026 · 0 likes A referral for a proper sleep study answers in one night what months of forum discussion cannot. That holds under the stated conditions and I have stated them.
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Coming back to: Batch date after test date, and other internal inconsistencies Replied, post #12 · Analytics › COA interpretation · 14 Jul 2026 · 12 likes A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to…
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Endotoxin and why it is a separate question from purity — what changed since Replied, post #76 · Analytics › Impurities & related substances · 13 Jul 2026 · 21 likes Racemisation produces a diastereomer that is mass-identical and chromatographically resolvable only on a method chosen for the purpose. Standard reversed-phase…
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Coming back to: Reconciling a supplier certificate with an independent result Replied, post #24 · Sourcing › Vendor reports · 10 Jul 2026 · 0 likes I read post #20 twice before replying, because I had assumed the opposite. Recording a reorder result against the original is one of the highest-value contributions…
Maintains 2 documents
- Reversed-phase HPLC for peptidesReview due 10 Jun 2027
- STEP-HFpEF — trial digestReview due 1 Jan 2027