The Lab

Reconstitution guides, a growing peptide reference, and bench-ready calculators. For research and educational reference only.

A capped Gansulin pen, a fine insulin syringe, a magnifying glass, and an unlabeled vial on a lab bench.
Refilling a GLP-1 Pen: What Reddit Gets Right

Refilling GLP-1 pens: we fact-check Reddit's top threads on 3 mL cartridges, cover reconstitution math, and share lab handling notes for research use. Read more...
A Gansulin pen and a glass cartridge under a magnifying glass, showing leftover liquid, in an ink-and-wash style.
Dead volume is stealing doses from your peptide pen

Dead volume is the fixed hollow channel running through a reconstitution pen needle and its cartridge connector that must be filled with liquid before any measured dose leaves the pen.... Read more...
Diagram of a U-100 syringe and a 1 mL vial on a lab bench with a calculator and notebook.
Peptide Blend Calculator: The Reddit DIY-Mix Math

Peptide blend calculator math explained: learn how Reddit DIY communities handle multi-compound reconstitution volume calculations for lab research reference. Read more...
An uncapped Gansulin peptide pen on a lab bench next to a magnifying glass, a plain notebook, and a glass vial.
Best Reusable Peptide Pen: The Reddit Debate

Reusable peptide pen vs disposable: Reddit's peptide community weighs in. We fact-check the debate and add reconstitution math for lab reference. Read more...
Comparison of a single-use vial with one syringe versus a multi-dose bacteriostatic water vial with multiple syringes.
Bacteriostatic water vs sterile water: the difference explained

The practical difference between bacteriostatic water and sterile water for research reconstitution, and how the benzyl alcohol preservative changes shelf life after opening. Read more...
Comparison of an 8 mm short-stopper cartridge and an 11 mm long-stopper cartridge under a magnifying glass.
How a sloppy cartridge transfer wastes your peptide vial

For research and educational reference only. PreppinPeppers sells laboratory hardware and materials (reconstitution pens, cartridges, and bacteriostatic water); it does not sell peptides or any substance for consumption. This is... Read more...
Diagram of a U-100 syringe and a 1 mL vial on a lab bench with a calculator, showing unit-to-volume conversion.
The Peptide Calculator Reddit Keeps Recommending

Peptide calculator Reddit keeps recommending — we break down the reconstitution math, unit conversions, and blend notes the research community relies on most. Read more...
A Gansulin pen rests in an open shipping box under a magnifying glass, illustrating a Reddit buyer's inspection guide.
The Gansulin Pen: A Reddit Buyer's Guide

Gansulin pen Reddit buyer's guide: fact-checked community insights on what it is, compatible cartridges, and reconstitution math for lab research. Read more...
Diagram of a U-100 syringe and 1 mL vial on a lab bench next to a glass cartridge and a small lab fridge.
3 ml glass cartridges explained: the 300-unit standard, seals and storage

What the standard 3 ml / 300-unit glass cartridge is, how the seals work, and how to store sealed cartridges properly. Read more...
An uncapped Gansulin pen with a needle showing a single droplet containing a beaded chain at the tip.
Stop Losing Peptides to Dead Volume: Prime Your Pen

Priming a click-dial pen is the step of clearing trapped air and residual liquid from the pen's needle, cartridge connection, and internal pathway before drawing research samples, ensuring the dialed... Read more...
An uncapped Gansulin pen, a balance scale with a syringe and vial, and a calculator on a lab bench.
The bench test that catches a misdosing peptide pen

Gravimetric testing is a bench method for verifying the accuracy of a peptide reconstitution pen by weighing its dispensed output on a 1mg-resolution balance, since 1mg of water equals 1µL... Read more...
Ink-and-wash drawing of a syringe, vials, cartridge, and a beaded chain spilling through a funnel on a lab bench.
What ruins your peptide during the vial-to-cartridge transfer

Vial-to-cartridge transfer is the laboratory step of moving a reconstituted peptide solution from its storage vial into a 3 ml glass cartridge using a sterile syringe and needle. Because the... Read more...
A gansulin pen review highlighting the metal body and 3 ml cartridge for research reconstitution.
Best Reusable Pens for Research Reconstitution: The Gansulin Metal Pen

Reusable pens for research reconstitution deliver consistent measured volumes from every vial — see how the Gansulin Metal Pen performs as lab hardware. Read more...
A Gansulin pen and glass cartridge next to a disposable syringe and plain unlabeled vial on a lab bench.
Reusable vs Disposable Peptide Pens: Which Is Better? (What Reddit Prefers)

Reusable vs. disposable reconstitution pens: we fact-check what Reddit prefers and cover the handling notes and math that matter for lab use. Read more...
Diagram of a U-100 syringe scale aligned with a 1 mL vial on a lab bench with a magnifying glass.
U-100 Units to Draw: The Reddit Explainer

Confused by U-100 units on a syringe? We fact-check the top Reddit peptide questions and break down the reconstitution math for lab research reference. Read more...
An uncapped Gansulin pen, its cap, and a glass cartridge with an arrow showing how to load it on a lab bench.
How to load a cartridge pen

A step-by-step walkthrough of seating a 3 ml cartridge in a reusable pen, attaching a needle, and priming out air, using the Gansulin metal pen as the example. Read more...
An uncapped Gansulin pen on a lab bench with a magnifying glass highlighting its dose-counter window.
How a precision click-dial pen works: reading the unit counter window and the click

A plain-English tour of the reusable metal cartridge pen: the dose knob, the dose window, the audible click, and the end-of-travel stop. Read more...
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