Method and system for calibrating a flow cytometer

A system for calibrating a flow cytometer to a refractive index X, the system comprising:

• a first mixture of particles, wherein the first mixture of particles is configured to be analyzed in the cytometer and results produced are recorded, wherein the first mixture comprises particles of refractive index X, wherein the particles of refractive index X have a plurality of different sizes;
• and
• a second mixture of particles, wherein the second mixture of particles is configured to be analyzed in the cytometer and results produced are recorded, wherein the second mixture comprises particles of refractive index Y, wherein refractive index Y does not equal refractive index X, and wherein the particles of refractive index Y have a plurality of different sizes, wherein there is at least a partial overlap between the particle sizes in the first and second mixtures, and wherein the size of at least one particle of the second mixture is known,
• wherein the results produced by the first and second mixture are configured to calibrate the cytometer to refractive index X.