MK-2866 (Ostarine) liquid solutions are available from Buy Ostarine Australia in three concentrations: 20mg/mL, 25mg/mL, and 30mg/mL. All three are dissolved in pharmaceutical-grade PEG-400 and carry the same ≥99% purity specification and independent CoA documentation. The question of which concentration is most appropriate for a given application comes down to assay design, volume constraints, and pipetting precision requirements.

This guide covers the practical considerations for each concentration. For background on MK-2866 as a research compound, see our MK-2866 Ostarine Research Guide. For a comparison of liquid versus powder versus capsule formats, see MK-2866 Formats for Research.

Understanding Concentration in Assay Design

When preparing working solutions for in-vitro research, the stock solution concentration determines the dilution volumes required to reach the target assay concentration. A higher stock concentration requires a smaller volume of stock to be added to the assay system, which reduces the total co-solvent (PEG-400) load in the final preparation.

For most cell-based assay systems, minimising co-solvent concentration in the working solution is preferable. PEG-400 is generally well tolerated at low concentrations but may affect cell viability or assay performance at higher levels. Researchers should verify PEG-400 tolerance for their specific cell line and assay format.

MK-2866 Liquid 20mg/mL

The 20mg/mL formulation is the lowest concentration in the liquid range and is suited to applications where slightly larger dispensing volumes are acceptable or preferred.

Practical scenario: If a cell-based assay requires a final MK-2866 concentration of 100nM in 1mL of culture media, and you are working from a 20mg/mL (approximately 51.4mM) stock, you would need to add approximately 1.94 microlitres of stock to achieve your target. At this volume, accurate pipetting with a calibrated micropipette is straightforward.

Best suited to: Applications requiring accurate low-volume dispensing with standard micropipette equipment; assays with moderate co-solvent tolerance; researchers preferring to work with slightly larger volumes to reduce pipetting error.

MK-2866 Liquid 25mg/mL

The 25mg/mL formulation sits in the middle of the liquid range and offers a balance between stock volume efficiency and dispensing precision.

Practical scenario: From a 25mg/mL (approximately 64.2mM) stock, achieving a 100nM final concentration in 1mL requires approximately 1.56 microlitres. The slightly smaller volume reduces co-solvent load relative to the 20mg/mL formulation.

Best suited to: General-purpose in-vitro assay work; laboratories requiring a single liquid concentration that balances preparation efficiency with solvent management; applications where intermediate co-solvent concentration is acceptable.

MK-2866 Liquid 30mg/mL

The 30mg/mL formulation is the highest concentration in our liquid range. It is designed specifically for applications where minimising solvent volume in the final assay preparation is a priority.

Practical scenario: From a 30mg/mL (approximately 77.1mM) stock, achieving 100nM in 1mL requires approximately 1.30 microlitres. The trade-off is that at sub-microlitre volumes, pipetting accuracy becomes increasingly important — any slight variation in dispensed volume has a proportionally larger effect on final concentration accuracy.

Best suited to: High-throughput screening formats where co-solvent minimisation is critical; preparation of high-concentration master stocks for further serial dilution; laboratories with validated sub-microlitre dispensing equipment.

Practical Dilution Reference

The table below shows the approximate stock volume needed to achieve common working concentrations in 1mL of assay volume from each of the three liquid formulations. All calculations assume MK-2866 MW = 389.33 g/mol.

• To achieve 1µM final: 20mg/mL → 19.4µL | 25mg/mL → 15.6µL | 30mg/mL → 13.0µL
• To achieve 100nM final: 20mg/mL → 1.94µL | 25mg/mL → 1.56µL | 30mg/mL → 1.30µL
• To achieve 10nM final: 20mg/mL → 0.194µL | 25mg/mL → 0.156µL | 30mg/mL → 0.130µL

At concentrations below 1µM final, sub-microlitre dispensing from any of these stocks introduces potential accuracy limitations. In practice, researchers typically prepare an intermediate dilution (e.g. a 1mM solution in aqueous buffer + 0.1% DMSO) from the PEG-400 stock before making final working dilutions.

Storage and Shelf Life

All three liquid concentrations share the same storage requirements: room temperature (15–25°C), away from direct light, in a sealed container. Do not freeze liquid solutions. Estimated shelf life is 24 months under appropriate conditions. Crystallisation at lower ambient temperatures is reversible with gentle warming and does not indicate compound degradation.

Each volume is supplied with an independent third-party Certificate of Analysis. CoA documents are available on our Lab Testing page indexed by batch number. For guidance on reading and verifying CoA documentation, see our COA verification guide.