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c/reconstitution·posted 9 months ago by u/wanjiru_varga

bacteriostatic water vs mg/mL — genuinely asking which matters more

Correction The Quiet One ×2 Slow Clap ×1 Cold Box ×1

Trying to settle this properly because the thread from last year went in circles.

The claim: bacteriostatic water matters. The counter-claim: it is measurement error. Both sides have been asserting it confidently for about 6 months without either producing anything.

What would actually settle it is 21 people measuring the same thing the same way. I have started; my numbers are below. They lean one way but not strongly enough for me to declare victory.

If you have data, post the data. If you have an opinion, flair it as an opinion.

4,521 up / 474 down91% upvoted51 commentsid 17fytu27 Oct 2025

51 comments

28 in this archive, depth 5

best — the order this archive was captured in

u/iman_falk616 points·9 months ago

the concentration on the vial in marker is the most important step

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u/wanjiru_vargaOP891 points·9 months ago

The confident tone is doing a lot of work that the evidence is not.

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u/anya_antonsen501 points·9 months ago

Yeah, showing the arithmetic is the fastest way for someone to spot the error.

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u/runa_cabrera209 points·9 months ago

Small correction: the trial was 3 weeks, not 16. Does not change your point but people will quote it.

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u/swirl_dont_shakereconstitution161 points·9 months ago·edited

dead space is real and the syringe matters

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u/sofia_danquah207 points·9 months ago

bacteriostatic and sterile water are not interchangeable, do not use them that way

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u/anjali_tamm360 points·9 months ago

swirl, do not shake, or you are courting oxidation

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u/rina_bergstrom0 points·9 months ago

The evidence standard in c/vendorvetting gets called too strict about once a month, and every time, the thread ends with the complainant agreeing.

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u/swirl_dont_shakeMOD1 point·9 months ago·edited

Flair changed to match the content. Read the sidebar before posting next time and we are square.

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u/quiet_reader_991 point·9 months ago

Yeah, showing the arithmetic is the fastest way for someone to spot the error.

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u/saskia_rahimi1 point·9 months ago

Slight fix: the number was 96.8, not 96.2. Decimal point, but a fairly consequential one.

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u/quarter_dose_queenlow and slow1 point·9 months ago

bacteriostatic and sterile water are not interchangeable, do not use them that way

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u/signe_grimaldi1 point·9 months ago·edited

This is correct. 2mL versus 21mL is the common mistake.

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u/kavya_radich1 point·9 months ago

This is the "correlation is mechanism" thing again. You changed three variables at once.

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[deleted]1 point·9 months ago

[deleted]

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u/wanjiru_vargaOP1 point·9 months ago

Cosigning. The concentration on the vial in marker is load-bearing.

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u/wanjiru_vargaOP1 point·9 months ago

i am begging people to write down the concentration

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u/emil_wojcik-33 points·9 months ago

Dead space in the needle hub holds a small but non-trivial volume. On low-volume draws that can be several units.

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u/gradient_goblin195 points·9 months ago

Cosigning. The concentration on the vial in marker is load-bearing.

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u/vial_math_verasyringe math121 points·9 months ago

What was the vial size and how much bac water?

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u/ines_lindqvist46 points·9 months ago

bacteriostatic and sterile water are not interchangeable, do not use them that way

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u/mateusz_achebe88 points·9 months ago

Inter-lab variance on this kind of assay is routinely 1–2 points. Different column, different gradient, different integration.

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u/vito_beaulieu63 points·9 months ago

Slight fix: the number was 98.1, not 98.3. Decimal point, but a fairly consequential one.

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u/marisol_frisk49 points·9 months ago

show your working or it is unhelpful

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u/adaeze_cabrera0 points·9 months ago

Water content matters more than people think. If a vial is carrying residual moisture, your "10mg" is not 10mg of peptide.

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u/units_not_mgsyringe math49 points·9 months ago

I am going to push back on this slightly.

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u/aurel_boateng15 points·9 months ago·edited

never post a calculation as advice without stating the concentration

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u/ilias_cabrera37 points·9 months ago

Are you using a u-100 or u-40 syringe? That changes everything.

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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.

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