How the calculator works
Undiluted Percoll products can be diluted directly to make a final working solution of known density, by the following procedure. In a measuring cylinder, add 1.5 M NaCl or 2.5 M sucrose to 1/10 of the final desired volume (e.g., 10 mL for 100 mL of working solution). To this, add the required volume of Percoll/Percoll PLUS (undiluted), calculated using the following formula. Make up to the final volume with distilled water.
The calculator is based on the formula: V0 = V (ρ - 0.1ρ10 - 0.9 / ρ0 - 1)
V0 = volume of Percoll (undiluted; mL)
V = volume of final working solution (mL)
ρ = desired density of the final solution (g/mL)
ρ0 = density of Percoll (undiluted) (g/mL; see Certificate of Analysis for exact density)
ρ10 = density of diluting medium (g/mL)
Examples of common diluting medium:
- For cell work: 1.5 M NaCl = 1.058 g/mL (minor differences for other salts)
- For subcellular particles or viruses: 2.5 M sucrose = 1.315 g/mL
The formula is useful for achieving densities that will be very close to the actual density desired. However, slight variations in volumes and densities of diluting media will affect final density. For determining highly accurate densities, measure the final density of Percoll solutions using a densitometer or refractometer.