DSIP FAQ: Storage, Mixing and Stability

The questions below are the ones researchers ask most about storing, mixing and handling DSIP. Each answer reflects the peptide’s sequence, Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu, and links to the fuller page where there is one.

How long does DSIP last in the fridge after mixing?

Mixed with bacteriostatic water and kept at 2 to 8 °C in the dark, DSIP lasts 8 to 12 weeks under Vistara Labs’ handling guidance, with quality slowly fading from around week 6 to 8. No published study covers DSIP in a sterile solution, so the window is general guidance that its chemistry supports. The full table is on how long DSIP lasts.

How long does unmixed DSIP powder last?

One supplier rates the solid at minus 20 °C at 4 years or more (Cayman Chemical, item 34426); another gives 3 years at minus 20 °C and 2 years at 4 °C, sealed and away from moisture and light (InvivoChem, V64516). Days at room temperature in transit do not harm the dry cake, so it ships without an ice pack.

Are DSIP and emideltide the same?

Yes. Emideltide is the international nonproprietary name for delta sleep-inducing peptide, and PubChem lists both as synonyms of one compound with the same nine-residue sequence (CID 68816). Some suppliers sell it as emideltide acetate, the acetate salt of the same peptide.

What is the weak point of DSIP in solution?

The tryptophan at position 1. It is among the residues most open to oxidation, which light, dissolved oxygen and trace metals drive, and its oxidation products are yellow. The single aspartate at position 5 changes slowly as well. The details are on the DSIP stability page.

What do you mix DSIP with?

Bacteriostatic water, which is sterile water with 0.9% benzyl alcohol so a refrigerated vial can be accessed more than once. DSIP is small and acidic, and one supplier rates its water solubility at about 100 mg/mL, so it dissolves fully without acid or other solvents. The reasons are on the DSIP solubility guide.

How much bacteriostatic water goes in a 5 mg DSIP vial?

There is no single correct volume. With 2 mL a 5 mg vial gives 2.5 mg/mL; with 1 mL it gives 5 mg/mL. More water spreads the same amount of peptide through a larger volume, so write the chosen concentration on the vial. The tables and calculator are on the DSIP reconstitution page.

Should DSIP be dissolved in acetic acid?

No. Dilute acetic acid is used in labs for hydrophobic or basic peptides that resist water, but DSIP dissolves readily without it. Acid also favours cleavage at its glycine-aspartate bond and moves the solution toward its calculated isoelectric point near pH 2.9, where it is least soluble.

Why is my DSIP cloudy or yellow?

Brief cloudiness that clears within 10 to 15 minutes is usually trapped air from adding water too fast or shaking. A peptide this soluble does not cloud on its own, so haze or particles that appear later point to contamination, warm storage or freezing. A yellow tint suggests the tryptophan has oxidised, usually from light. Either way the solution is discarded. More in why peptides gel or go cloudy.

Can you freeze mixed DSIP?

Not a vial that will be opened again, because repeated freezing and thawing promotes aggregation in peptide solutions and warms the solution each time. Laboratories that need frozen solution divide it into single-use aliquots and thaw each one once; one supplier gives such stock 1 month at minus 20 °C and 6 months at minus 80 °C. Sealed powder can be frozen without concern.

Does DSIP nasal spray keep as long as a mixed vial?

Not by assumption. The spray is a different preparation, ready-mixed in sterile saline, so an opened bottle lasts as long as its label allows. It is kept at 2 to 8 °C, upright, capped and dark, dated when first opened and never frozen. The routine is in how to store a peptide nasal spray.