Concentration calculator

Weight/volume percent, where 1% w/v equals 10 mg/mL.

What this calculates

Weight/volume percent describes how much solid is dissolved in a given volume of liquid: a 1% w/v solution is one gram of material in 100 mL, which is the same thing as 10 mg/mL. The calculator multiplies your target percentage by your final volume to give the mass of GHK-Cu that volume requires.

Worked through: a 2% w/v solution at 30 mL needs 2% of 30 mL expressed as mass — 0.6 g, or 600 mg. Halve the volume and you halve the mass; the concentration is unchanged. This is arithmetic about a solution, not a recommendation about a quantity.

What to check before preparing GHK-Cu

• Starting material. Crystallised from aqueous copper(II) acetate with ethanol it forms dark purple-blue octahedral crystals; in column purification the complex is collected as the elution peak absorbing at 600 nm. Stated under the cosmetic safety review's Method of Manufacture heading for copper tripeptide-1, so it describes the copper complex rather than the uncomplexed peptide. The underlying source is Pickart and Lovejoy, Methods in Enzymology 1987. source
• Solubility. Highly hydrophilic. Octanol / phosphate-buffered-saline distribution coefficients (log D) measured between -2.38 and -2.49 across the pH range 4.5 to 7.4. source A target concentration above what the compound will dissolve produces a suspension, not a solution, and the calculator has no way to know that — it does the arithmetic either way.
• Storage. This is an accelerated stability finding, not a handling instruction. Under forced-degradation testing the complex remained stable in water and in pH 4.5 to 7.4 buffers held at 60 degrees C for at least two weeks, while basic and oxidative stressors, and to a lesser extent acidic stress, caused hydrolytic cleavage with first-order degradation profiles. A 60 degrees C challenge is a stress condition used to measure degradation kinetics; it is not a holding temperature, and the published literature does not establish one. source

What the number does not tell you

The result assumes the vial contains the mass its label states and that the material is what the label says it is. Neither is established by arithmetic. Both come from an assay — what HPLC and mass spectrometry establish — and the published record on GHK-Cu has limits worth reading before treating any figure as settled.