GLPHubglpresearchhub.com
Read-only archive. GLP Research Hub is a static community record — nothing here is for sale, no account is needed, and no vote you cast is counted. Why?
607
c/reconstitution·posted 5 months ago by u/niels_roos

why does nobody talk about concentration

PSA Clean Column ×6

why does nobody talk about concentration. Searched first, found three threads that contradict each other, hence the post.

Wrote the date on the vial as well as the concentration after losing track of which one was opened first.

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

The dead space question sent me down a rabbit hole for a week. It is a fraction of a unit and it is the same every draw.

Research-use-only material is not approved for human use and nothing here should be read as a recommendation to use it.

621 up / 14 down98% upvoted29 commentsid 55q6q08 Feb 2026

29 comments

21 in this archive, depth 5

best — the order this archive was captured in

u/andres_sorensen44 points·5 months ago

Aim the stream down the wall of the vial rather than into the cake. Reconstitution is a solubility problem, not a mixing problem, and mechanical shear does nothing helpful.

replysharereportpermalink
u/bac_water_banditMOD23 points·5 months ago

Corrected the concentration in the title, which contradicted the body. Nothing else touched.

replysharereportpermalink
[removed]17 points·5 months ago

[removed by moderator]

replysharereportpermalink
u/georgi_adebayo38 points·5 months ago

the powder cake sits at the bottom, the volume you add is the volume that counts

replysharereportpermalink
u/rasmus_mensah20 points·5 months ago

Agreed — units are volume. Once that lands, the rest of the arithmetic is one division.

replysharereportpermalink
u/emil_wojcik13 points·5 months ago

Pushback on the syringe advice: a U-100 barrel reads units of volume. Calling them "doses" is how the confusion starts.

replysharereportpermalink
u/gradient_goblin5 points·5 months ago

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

replysharereportpermalink
u/yusuf_nakamura17 points·5 months ago

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

replysharereportpermalink
u/niels_roosOP8 points·5 months ago

a U-100 syringe reads 100 units to the millilitre, every time

replysharereportpermalink
u/yusuf_achebe-13 points·5 months ago

Are you accounting for the powder volume, or is that where the confusion is?

replysharereportpermalink
u/sleep_apnea_sam1 point·5 months ago·edited

Did the maths give you a whole number of units, or a fraction?

replysharereportpermalink
u/rina_bergstrom1 point·5 months ago·edited

What concentration did you actually reconstitute at, rather than what did you intend to?

replysharereportpermalink
u/niels_roosOP1 point·5 months ago

Show the arithmetic — where did the unit figure come from?

replysharereportpermalink
u/rina_bergstrom1 point·5 months ago

Show the arithmetic — where did the unit figure come from?

Adding one thing — put the date on the label too. Concentration plus date and you can never mix two vials up.

replysharereportpermalink
u/swirl_dont_shakereconstitution1 point·5 months ago

Adding one thing — put the date on the label too.

Right, and the arithmetic behind it: 30mg in 3mL is 10mg/mL, so 0.5mg is 5 units.

replysharereportpermalink
u/saskia_mwangi1 point·5 months ago

label the vial with the date as well as the concentration

replysharereportpermalink
u/elin_ferrari1 point·5 months ago

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

replysharereportpermalink
load more comments (3) →
u/ruben_cabrera5 points·5 months ago

How many mg in the vial and how many mL are you adding?

replysharereportpermalink
Permalinked branches
Deep branches get their own page so a single reply chain can be linked and read on its own.
About c/reconstitution

The arithmetic and the technique. Bacteriostatic versus sterile water, reconstitution volume as a concentration choice, converting mg/mL into insulin-syringe units, dead space, swirl-not-shake, stopper coring, and how long a reconstituted vial is actually good for. Math errors get corrected fast and politely.

88kmembers
130submissions
Aug 2023created
submissions / month, last year
Sponsored

Sigma-Aldrich Standards

Certified reference materials for peptide identity and purity work.

sigmaaldrich.com
c/reconstitution rules
  1. Show your numbers. "How many units?" with no mg and no mL cannot be answered.
  2. Never post a calculation as advice without stating the concentration it assumes.
  3. No sterile-compounding-for-others discussion. Personal handling only.
  4. Independent community. Nobody here sells anything, and anyone who tries is banned.
  5. Not medical advice. Describe what you did; never prescribe to a stranger.
  6. Claims need evidence. Batch numbers, dated screenshots, independent test reports, or a citation.
  7. No referral links, discount codes or affiliate URLs. Permanent ban, no appeal.
  8. No contact handles, wallet addresses or tracking numbers — they identify people.
  9. Be recognisably decent. Disagree hard, insult nobody.
Moderators
Volunteers. Unpaid, unaffiliated, and reachable through modmail only.
Before you read on

Several compounds discussed on GLP Research Hub are sold for research use only and are not approved for human use anywhere. Nothing here is medical advice and none of it is written by your clinician. If a post reads like an instruction, treat it as a description of what one stranger did.