How can you determine if the observed pigment spots are single pure pigments or a mixture?

To determine if the observed pigment spots are single pure pigments or a mixture, using a different chromatography solvent or stationary phase is effective because chromatography works by separating components based on their interactions with the mobile and stationary phases. If the pigment spots are mixtures, changing the solvent or stationary phase can alter the separation characteristics, potentially causing the individual components to move differently and become distinguishable. This might help in identifying if the original spots are indeed composed of multiple pigments by separating them further, thus allowing for the observation of additional spots corresponding to different pigments that were not resolved under the initial conditions.

In contrast, increasing the sample size may not contribute to resolving the pigments as it could lead to overlapping spots, while leaving the samples in the light longer would not influence their separation. Changing the temperature of the experiment might affect the viscosity of the solvent or the solubility of the pigments, but it does not directly address the issue of how the pigments are chemically or physically mixed.