Which technique is used to observe the different pigments in a material?

Which technique is used to observe the different pigments in a material?

• A. Paper chromatography
• B. Chromatography
• C. Diafiltration
• D. Thin-Layer Chromatography

Answer: (A)

Pigment separation relies on how substances partition between a stationary phase and a mobile phase. In paper chromatography, the stationary phase is the cellulose in the paper and the mobile phase is a chosen solvent that travels up the paper by capillary action. When you apply a pigment extract to the paper and develop it in the solvent, each pigment has a different tendency to stick to the paper versus dissolve in the solvent. That difference in affinity causes the pigments to move different distances, so you end up with separate colored spots that reveal the different pigments present in the material. This method is simple, inexpensive, and directly visualizes multiple pigments in one run, which is why it’s the go-to technique for observing pigment mixtures. The other options aren’t as suited for this purpose: diafiltration uses membrane size separation rather than chemical affinity, so it doesn’t reveal pigment composition; broader “chromatography” isn’t as specific, since it could refer to several techniques; and thin-layer chromatography is similar in principle but requires a plate and setup beyond the classic paper-based approach used for straightforward pigment observation.

Pigment separation relies on how substances partition between a stationary phase and a mobile phase. In paper chromatography, the stationary phase is the cellulose in the paper and the mobile phase is a chosen solvent that travels up the paper by capillary action. When you apply a pigment extract to the paper and develop it in the solvent, each pigment has a different tendency to stick to the paper versus dissolve in the solvent. That difference in affinity causes the pigments to move different distances, so you end up with separate colored spots that reveal the different pigments present in the material. This method is simple, inexpensive, and directly visualizes multiple pigments in one run, which is why it’s the go-to technique for observing pigment mixtures. The other options aren’t as suited for this purpose: diafiltration uses membrane size separation rather than chemical affinity, so it doesn’t reveal pigment composition; broader “chromatography” isn’t as specific, since it could refer to several techniques; and thin-layer chromatography is similar in principle but requires a plate and setup beyond the classic paper-based approach used for straightforward pigment observation.