Organic Chemistry MCAT Practice Exam

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Master Organic Chemistry for the MCAT. Use flashcards and multiple choice questions to understand concepts, with each question offering hints and detailed explanations. Prepare effectively for your exam!

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What does High-Performance Liquid Chromatography (HPLC) primarily rely on for elution?

Polar stationary phase
Non-polar stationary phase
Electrostatic interaction
Hydrogen bonding

The correct answer is: Non-polar stationary phase

High-Performance Liquid Chromatography (HPLC) primarily relies on a non-polar stationary phase for elution, especially in reversed-phase HPLC, which is the most common form. In this technique, the stationary phase is typically made of non-polar materials, which interact with non-polar analytes in the sample. The mobile phase, on the other hand, is more polar. As the sample is introduced into the column, non-polar compounds will preferentially interact with the non-polar stationary phase and elute slower, while more polar compounds will interact less and elute more quickly. This contrasting interaction creates a separation based on polarity, which is fundamental to the principles of HPLC. It is essential to understand this mechanism as it underpins the efficiency and resolution of the separation process employed in HPLC.