Glutathione Reconstitution — Volume and Concentration Reference

Published 2026-10-13 · Lyophile Editorial

Glutathione ships as a lyophilized powder in 200 mg, 500 mg, and 1 g vials, and it's one of the least forgiving peptides to reconstitute. Two reasons: the volume math breaks down at high vial masses, and the thiol oxidizes. This page leads with the math, then the handling notes.

For research use only — not clinical guidance.

Glutathione reconstitution calculator logic (work the math by hand)

Every number below comes from one relationship: concentration = mass ÷ volume. Nothing else.

Step 1 — Convert vial mass to micrograms. 1 mg = 1000 mcg. A 500 mg vial is 500,000 mcg.

Step 2 — Divide by diluent volume in mL. 500,000 mcg ÷ 10 mL = 50,000 mcg/mL.

Step 3 — Convert to per-unit on a U-100 insulin syringe. U-100 is marked so 100 units = 1 mL, so 1 unit = 0.01 mL. 50,000 mcg/mL × 0.01 mL/unit = 500 mcg per unit.

That last step is where most errors happen. At glutathione's typical vial sizes the per-unit figure lands in the hundreds of micrograms, not the single digits researchers are used to from smaller peptides.

| Vial mass | Diluent volume | Concentration | Per unit (U-100) | |---|---|---|---| | 200 mg | 2 mL | 100,000 mcg/mL | 1000 mcg/unit | | 200 mg | 5 mL | 40,000 mcg/mL | 400 mcg/unit | | 500 mg | 5 mL | 100,000 mcg/mL | 1000 mcg/unit | | 500 mg | 10 mL | 50,000 mcg/mL | 500 mcg/unit | | 1000 mg | 10 mL | 100,000 mcg/mL | 1000 mcg/unit | | 1000 mg | 20 mL | 50,000 mcg/mL | 500 mcg/unit |

Read the table as a grid, not a recommendation. Any vial mass over any diluent volume produces a valid concentration; the table just saves you the arithmetic.

How much bacteriostatic water for a 500 mg glutathione vial?

A 500 mg vial reconstitutes cleanly in 5–10 mL of bacteriostatic water: 100,000 mcg/mL at 5 mL, 50,000 mcg/mL at 10 mL. Bacteriostatic water contains 0.9% benzyl alcohol as a preservative per its USP monograph, which is why it's used for multi-draw vials rather than single-use work.

The trade-off is real. More diluent means finer per-unit resolution on the syringe and a lower concentration that oxidizes more slowly per unit volume; less diluent means fewer units to draw but a more concentrated solution sitting in more headspace oxygen. For glutathione specifically, 10 mL / 500 mg is the common middle ground because it keeps the per-unit figure at a round 500 mcg.

How much bacteriostatic water for a 1 g vial?

A 1 g (1000 mg) vial needs 10–20 mL of diluent to stay in a workable concentration range. At 10 mL: 100,000 mcg/mL (1000 mcg per U-100 unit). At 20 mL: 50,000 mcg/mL (500 mcg per unit). The 1 g vial is the one most likely to blow past the solubility you expect.

Practical ceiling: pushing a 1 g vial into 5 mL asks for 200 mg/mL — thick, slow-dissolving. Add diluent in 2–3 mL increments and swirl, don't shake. Glutathione foams, foam is surface area, and surface area is oxidation.

Reconstitution steps, in order

1. Bring vial and diluent to room temperature. Cold diluent slows dissolution and tempts you to shake.
2. Wipe the stopper with a fresh alcohol swab and let it dry fully. Wet alcohol carries into the vial.
3. Draw your target diluent volume with a syringe sized to that volume, not larger. A 10 mL draw through a 20 mL syringe has worse volumetric accuracy at the mark.
4. Insert the needle at a shallow angle against the vial wall and let the diluent run down the glass. Don't aim the stream at the powder bed — direct impact and the resulting foam both cost you.
5. Swirl gently. No vortex. No shaking.
6. Let it stand until the solution is clear. Undissolved glutathione reads as a faint haze.
7. Label the vial with date and concentration. Concentration, not just volume — future-you won't remember which diluent volume you used.

Light and oxidation sensitivity: what actually degrades glutathione

Glutathione's reactive group is its thiol (–SH), and the thiol is what oxidizes. Two glutathione molecules form glutathione disulfide (GSSG), and that conversion is the primary degradation pathway in aqueous solution. Once GSSG forms, the solution is no longer a single-species preparation.

What accelerates it:

• Dissolved oxygen. Every mL of headspace air above the liquid is oxygen available to the thiol.
• Light, particularly UV. Amber vials or foil wrap are the standard mitigations.
• Trace metal ions, especially copper and iron. These catalyze thiol oxidation, which is why diluent quality and clean technique matter more here than for a typical peptide.
• Elevated temperature. Cold slows the reaction; room temperature is a compromise between degradation rate and dissolution speed.
• Alkaline pH. Thiol oxidation accelerates as pH rises above neutral.

What slows it: minimizing headspace, keeping the vial sealed between draws, working cold where practical, and using a diluent free of metal contamination.

Is bacteriostatic water the right diluent for glutathione?

Bacteriostatic water is the standard choice for multi-draw glutathione vials because the 0.9% benzyl alcohol preservative suppresses microbial growth across repeated punctures. It is not a thiol stabilizer — benzyl alcohol does nothing to slow oxidation. Sterile water for injection is the alternative when the preservative itself is a variable you want to remove.

| Diluent | Preservative | Multi-draw suitability | Effect on thiol oxidation | |---|---|---|---| | Bacteriostatic water (0.9% benzyl alcohol) | Yes | Yes | None — neutral | | Sterile water for injection | No | Single-use only | None — neutral | | Saline (0.9% NaCl) | No | Single-use only | Chloride and trace metals can catalyze oxidation |

Neither diluent protects the thiol. Diluent choice is about microbial control and whether you need repeated access, not chemical stability.

Storage after reconstitution

Reconstituted glutathione is less stable than the lyophilized powder. The powder itself is comparatively robust at controlled room temperature, but once water is added the clock starts.

Store reconstituted solution refrigerated, protected from light, with minimal headspace. Avoid repeated freeze–thaw cycles. If you must freeze aliquots, freeze once, in single-use portions, and thaw only what you need — every thaw cycle is another temperature excursion and another round of oxygen contact.

Common failure modes

• Wrong per-unit figure. Recalculating 500 mg in 5 mL as "500 mcg per unit" instead of 1000. Recheck step 3 every time.
• Shaking to speed dissolution. Foam equals oxidation. Swirl.
• Over-concentrated 1 g vials. 200 mg/mL is not a practical working solution.
• Leaving the vial on the bench. Light and warmth both push the thiol toward GSSG.
• Using a single large syringe for a small draw. Volumetric accuracy degrades at the low end of a syringe's range.

Where to source bacteriostatic water

• BAC Water Depot — bacteriostatic water, 0.9% benzyl alcohol, US-shipped.
• Med Lab Supply — sterile diluents and lab consumables.
• Mountain West Medical — bacteriostatic and sterile water for injection.

Where to source research peptides

• Alpha Amino USA — per-lot HPLC/MS COA, US-shipped.
• Limitless Biotech — research-grade lyophilized peptides with published COAs.
• Peptide Sciences — research peptides with third-party analytical documentation.

For research use only — not clinical guidance.