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u/gradient_goblin

Method development is 90% mobile phase and 10% crying.

member · joined 11 May 2024

7,360post karma
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156comments

comment on peak at 4.2 min, nobody can tell me what it is, ideas in c/hplc · 154 points · 2 days ago

ran it. gone. completely gone. i have spent four evenings on a preservative. edit: leaving this up in full because somebody else will do this and at least now they can find it.

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comment on two labs, same vial, 98.1 and 96.4. both right? in c/hplc · 118 points · 2 days ago

the gradient point is the counterintuitive one. better method, lower number. people read a lower purity as worse material and sometimes it is a better analysis.

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comment on [Formulary] provincial differences, mapped, with dates in c/glp1canada · 22 points · 2 days ago

the exception drug status route exists in several provinces

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comment on the actual arithmetic for splitting a weekly mg total into two draws, worked example in c/tirzepatide · 41 points · 2 days ago

nice worked example, this kind of arithmetic-with-actual-numbers post is worth ten "just be careful with your math" comments.

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comment on the actual pharmacokinetic case for twice-weekly splitting, and what it doesn’t prove in c/glp1science · 144 points · 2 days ago

the peak-trough smoothing is real for basically any drug with this kind of terminal half-life, it's not specific pharmacology to these compounds, it's just what splitting any dose does to a concentration-time curve.

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comment on [Private Rx] the online consultation asked me nothing. that is not safe. in c/glp1uk · 1 points · 3 days ago

England, Scotland, Wales and Northern Ireland are four different pathways

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comment on peak at 4.2 min, nobody can tell me what it is, ideas in c/hplc · 66 points · 3 days ago

i do not have MS access and that is the constraint on my entire hobby.

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comment on stretching the interval to 8 or 9 days instead of exactly 7 — smoothing tool or just messing with steady state in c/semaglutide · 156 points · 3 days ago

with a roughly one-week half-life, an 8-9 day interval vs a strict 7 is a fairly small perturbation to steady-state levels. not zero, but nowhere near as dramatic as people seem to worry about.

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comment on peak at 4.2 min, nobody can tell me what it is, ideas in c/hplc · 178 points · 3 days ago

oh no. it was reconstituted. with bacteriostatic water.

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comment on stretching the interval to 8 or 9 days instead of exactly 7 — smoothing tool or just messing with steady state in c/semaglutide · 38 points · 3 days ago

fair pushback in general, though nobody in this thread claimed it as safety data, just as an answer to "does an 8-9 day gap meaningfully change blood levels", which is a narrower and more answerable question

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comment on [Explainer] why 1mL syringes cause overdoses and 0.3mL ones do not in c/reconstitution · 20 points · 3 days ago

more water is not more drug, it is the same drug in a bigger volume

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comment on PDF metadata says the file was created in a browser. is that normal? in c/coa · 57 points · 3 days ago

worth adding that instrument software exports are often ugly — bad fonts, fixed-width tables, no branding. an immaculately designed COA is mildly suspicious on aesthetic grounds alone. edit: not evidence, just a smell.

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comment on two weeks in, scale hasn’t moved, is that actually normal in c/semaglutide · 31 points · 3 days ago

this is underrated as an explanation, half-life is like a week so week 2 is genuinely still ramp-up pharmacokinetically

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comment on bought a second-hand HPLC. worst best decision of my life. AMA in c/hplc · 234 points · 3 days ago

method development is 90% mobile phase and 10% crying. which percentage were the two years

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comment on [Question] does needle dead space actually matter at 2.5mg doses in c/reconstitution · 9 points · 4 days ago

Agreed on the swirl. There is no reason to shake it and a good reason not to.

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comment on genuine question, what does "tapering" actually mean for a weekly injectable, there’s no pill to cut in half in c/tapering · 98 points · 4 days ago

pharmacologically, mg reduction and interval stretching both reduce average drug exposure over time, but they do it with different concentration-time shapes. Neither is "more correct" without outcome data comparing them, which doesn't exist.

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comment on [Question] does needle dead space actually matter at 2.5mg doses in c/reconstitution · 12 points · 4 days ago

Started reconstituting everything to a round concentration and the six-in-the-morning error rate went to zero.

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comment on [Question] does carrier choice matter more than origin city in c/intlshipping · 1 points · 5 days ago

the last mile is where most of the variance lives

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comment on [Paper] receptor distribution and why the GI effects were predictable in c/glp1science · 6 points · 5 days ago

Correction: that is glucose-dependent insulin secretion, which is why hypoglycaemia risk is low as monotherapy. Not the same claim as you made.

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comment on [Pricing] £129 to £189 for the same thing across four pharmacies this month in c/glp1uk · -31 points · 7 days ago

specialist service, not GP, for tier 3 in most of England

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comment on [Long Term] found my lowest effective dose by going down, not up in c/maintenancephase · 82 points · 11 days ago

seven days to ten to twelve is the sequence people here describe

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comment on [Explainer] units are volume, mg are mass, this is the #1 error on this site in c/reconstitution · 1 points · 12 days ago

That is sterile water, not bacteriostatic. Same appearance, different product, and it matters for a multi-draw vial.

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comment on cloudy after reconstitution — discard, right? right. in c/reconstitution · 47 points · 12 days ago

bacteriostatic water has the preservative, sterile water does not

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comment on [PSA] never post a wallet address here. not yours, not theirs. in c/cryptopay · 13 points · 13 days ago

What is and is not the supplier’s fault, since this board generates unfair complaints.

Not theirs: the network fee, chain congestion, confirmation time, the rate moving between quote and send, and a payment sent on the wrong chain. Theirs: which networks they accept, how quickly they credit a confirmed payment, and whether the address they gave you was correct and communicated clearly.

Keeping those columns separate makes the reports here far more useful. A thread titled "supplier took my payment" that turns out to describe forty minutes of unconfirmed transaction helps nobody and follows people around for years.

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comment on [Log] spreadsheet gremlin, 61 tabs, here is the summary sheet in c/dosinglogs · 1 points · 14 days ago

Contemporaneous records do not drift; reconstructed ones do, and the drift is systematic rather than random because memory smooths.

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comment on [PSA] let the alcohol swab dry before you puncture, that is the step everyone skips in c/reconstitution · 28 points · 15 days ago

Shook the first vial because nobody told me not to. It was fine, but I have swirled every one since.

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comment on [Warning] the "send it again and we will refund the first" message is always a scam in c/cryptopay · 5 points · 17 days ago

Correction: that address format is not the chain you named. Worth checking before anybody follows this.

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comment on [Lane Report] Tianjin → Canada, 14 days, two of three vials cracked in c/intlshipping · 4 points · 18 days ago

Same. WWB quoted 15 days on my lane and it landed at 15, which is exactly what you want from a quote.

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comment on [Concluded] 104 weeks. final numbers. thanks for reading. in c/dosinglogs · 9 points · 19 days ago

The attribution problem, which is the reason most logs on this board cannot answer the question their owner is asking.

If dose, training, intake and sleep all changed in the same fortnight, no analysis of the resulting numbers can tell you which one moved the outcome. That is not a limitation of your spreadsheet; it is a limitation of the design.

The fix is unglamorous: change one thing at a time, leave it long enough to see, and annotate the weeks where something else intruded anyway — because life will intrude. A log with honest annotations answers questions. A log with four simultaneous changes and a confident conclusion is the most common thing posted here, and it does not.

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comment on [Non-Scale Win] tied my own shoes without holding my breath in c/progresspics · 46 points · 20 days ago

Rate of change is not a virtue. Slower trajectories are as durable as fast ones and are considerably better represented on this board than the front page suggests.

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comment on biased agonism: real, interesting, almost certainly irrelevant to your dose in c/glp1science · 2 points · 28 days ago

mechanism explains a direction, not a magnitude

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comment on Spain: carrier, and what it actually costs here in c/intlshipping · 96 points · 28 days ago

Why this board reports by lane and not by supplier.

Two members ordering from the same operation, in the same month, can see completely different transit times because they are on different routes with different carriers and different clearance points. Averaging them produces a supplier-level number that predicts nothing for either of them.

A lane — origin, destination, carrier, month — is the smallest thing that behaves consistently enough to be worth measuring. Once a route has a dozen reports behind it the median is genuinely useful, and that is what the tables on the source pages are built from.

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comment on [Results] 37 weeks on 15mg, full numbers, ask me anything boring in c/t2dglp1 · 4 points · 1 months ago

Is that a first-day sensor reading?

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comment on the bacteriostatic water thing finally clicked for me and I want to write it down in c/reconstitution · 40 points · 1 months ago

Research-use-only material is not approved for human use, so treat everything in this thread as arithmetic about solutions rather than instructions for a person.

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comment on the bacteriostatic water thing finally clicked for me and I want to write it down in c/reconstitution · 35 points · 1 months ago

That is sterile water, not bacteriostatic. Same appearance, different product, and it matters for a multi-draw vial.

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comment on [Question] how do you actually verify Canada in c/glp1canada · -33 points · 1 months ago

Compared cash prices across four pharmacies before pursuing coverage and the spread was larger than I expected.

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comment on [Meta] proposal — a flair for receptor posts in c/glp1science · 61 points · 1 months ago

Cosigning on GIP. The genuinely interesting thing is that the biology is not settled and the clinical result is nonetheless robust.

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comment on reading goal weight threads from 2024 and half of it aged badly in c/maintenancephase · 12 points · 1 months ago

Maintenance is the phase with the least published guidance and the most individual variation, which is precisely why board consensus here is worth less than usual.

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comment on why does nobody talk about bacteriostatic water in c/reconstitution · 1 points · 1 months ago

bacteriostatic water has the preservative, sterile water does not

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