Final answer:
High Performance Liquid Chromatography (HPLC) is the chromatography technique that separates small sizes including a stationary phase, solvent mobile phase, and UV detector, allowing for the separation of closely related compounds like phosphatidylcholines.
Step-by-step explanation:
The type of chromatography that separates small sizes and includes a stationary phase, solvent mobile phase, and a detector (UV) is High Performance Liquid Chromatography (HPLC). This technique involves passing a solution through a column that contains very fine particles making up the stationary phase. Some solutes bind more strongly to these particles, thus moving slowly through the column, while others pass through quickly, allowing for effective separation. HPLC can be monitored by a UV detector, capturing the chromatogram, a graphic representation of the separation where each peak corresponds to a different solute based on their retention time. The use of HPLC-UV is particularly valuable for separating compounds like phosphatidylcholines, which have very similar structures but can be differentiated based on their hydrophobicity and affinity to the stationary phase.