In: Chemistry
what distills first in the 3 types of chromatography? Like do polar or non polar molecules go through first in Simple, fractional, and gas chromatography and what type of solvents (polar or nonpolar) are best for each type of chromatography? thanks
Mobile phase in simple chromatography is solution that travels up stationary phase due to capillary action. Mobile phase is generally mixture of polar organic solvent with water while stationary phase is water. Particle size of stationary phase is generally finer as compared to other phase in system. In simple and fractional chromatography techniques basically, a more polar solvent is preferred because less polar solvent will not compete well, allowing compounds to remain bound to stationary phase, resulting in slow elution. A polar solvent will compete well with molecules and will occupy sites on stationary phase. In gas chromatography, a little difference occurs as stationary phase is liquid and mobile phase is gas. As carrier gas sweeps down through column, motion is inhibited by analyte. The rate depends on strength of adsorption which in turn depends on type of molecule and on stationary phase material.