Clear glass vial beside a volumetric flask and glass pipette on a cool blue laboratory bench, representing 10 mg vial stock concentration math for research.

PT-141 10 mg Vial: Stock Concentration Math (In Vitro)

Key takeaways

10 mg of PT-141 at 1025.18 g/mol is about 9.75 micromoles of peptide.
Stock concentration depends only on solvent volume: 10 mg in 1 mL is 10 mg/mL or about 9.75 mM.
The listed Happy Peptides vial is 9 mg: in 1 mL that is 9 mg/mL or about 8.78 mM.
Dilute to assay concentrations with C1V1 = C2V2 and account for net peptide content.
For in vitro research use only.

A PT-141 10 mg vial contains about 9.75 micromoles of peptide (10 mg divided by 1025.18 g/mol), so the stock concentration is set entirely by the solvent volume you add: 10 mg in 1 mL gives 10 mg/mL, or about 9.75 mM. This guide works through the concentration arithmetic for PT-141 for in vitro assay preparation. Happy Peptides lists the PT-141 vial at 9 mg, so a 9 mg column is included alongside the 10 mg values.

How do you convert mg per mL to molarity?

Molarity (mol/L) equals mass concentration (g/L) divided by molecular weight (g/mol). With a molecular weight of 1025.18 g/mol, 1 mg/mL equals 1 g/L, which is 0.9754 mM.

What stock concentrations result from common solvent volumes?

Solvent volume	10 mg vial (mg/mL)	10 mg vial (mM)	9 mg vial (mg/mL)	9 mg vial (mM)
1 mL	10.0	9.75	9.0	8.78
2 mL	5.0	4.88	4.5	4.39
3 mL	3.33	3.25	3.0	2.93
5 mL	2.0	1.95	1.8	1.76
10 mL	1.0	0.98	0.9	0.88

How do you dilute a stock to assay working concentrations?

Use C1 x V1 = C2 x V2. For example, a 1 mM intermediate stock diluted 1:100 in assay buffer gives 10 micromolar, and a further half-log series (10 uM, 3.16 uM, 1 uM, and so on) down to the picomolar range covers a typical concentration-response curve for a melanocortin-receptor cAMP assay. Keep final solvent content constant across all wells, including the vehicle control.

What affects the accuracy of the math?

Net peptide content: lyophilized powder includes counter-ions and residual water, so the true peptide mass can be below the label value. Use the content figure from the certificate of analysis where it is provided.
Solvent choice: follow the solubility guidance on the COA; a sterile solvent such as Reconstitution Solution is a common choice for aqueous stocks.
Handling: prepare single-use aliquots to limit repeated freeze-thaw cycles.

To confirm the material itself before doing the math, see verifying PT-141 identity by CAS and mass spec; for assay design context, see the PT-141 structure and receptor profile.

Related research guides

Research-use note

All materials discussed are supplied for in vitro laboratory research use only, and are not for human or animal use.

Frequently asked questions

What is the molarity of a PT-141 10 mg vial in 1 mL?

A PT-141 10 mg vial contains about 9.75 micromoles (10 mg divided by 1025.18 g/mol), so 10 mg in 1 mL is 10 mg/mL, or about 9.75 mM. View PT-141

How do I convert mg/mL to millimolar?

Divide the concentration in g/L by the molecular weight 1025.18 g/mol; 1 mg/mL equals about 0.975 mM.

What if my vial is 9 mg?

Scale proportionally: 9 mg in 1 mL gives 9 mg/mL, or about 8.78 mM.

Why might the true concentration differ from the calculation?

Lyophilized peptide contains counter-ions and residual water, so net peptide content can be below the label mass; use the COA content figure. PT-141 COA and purity

Is it for human or animal use?

No. It is supplied for in vitro laboratory research use only.