HPLC

Which of the following best describes the main difference between Thin Layer Chromatography (TLC) and High-Performance Thin Layer Chromatography (HPTLC)?

• TLC uses a mobile phase, while HPTLC does not.

• HPTLC uses a thicker stationary phase than TLC.

• HPTLC employs finer sorbent particles and more precise sample application for higher resolution.

• TLC is automated, whereas HPTLC is always manual.

Which type of chromatography is most commonly used in pharmaceutical analysis when using High-Performance Liquid Chromatography (HPLC)?

• Normal-phase chromatography, using a polar stationary phase and non-polar mobile phase

• Reverse-phase chromatography, using a non-polar stationary phase and polar mobile phase

• Gas chromatography, due to its higher resolution

• Size-exclusion chromatography, mainly for volatile compounds

Why is a degasser used in High-Performance Liquid Chromatography (HPLC)?

• To increase the pressure in the column for better separation

• To remove particulate matter from the mobile phase

• To remove baseline noise

• To change the polarity of the mobile phase for better retention

Which of the following best describes the difference between isocratic and gradient elution modes in HPLC?

• Isocratic elution uses a constant mobile phase composition, while gradient elution gradually changes the solvent composition during the run

• Isocratic elution changes the composition of the mobile phase over time, while gradient elution keeps it constant

• Both elution modes use only water as the mobile phase

• Gradient elution is only used for non-polar compounds, while isocratic is for polar compounds only

Which of the following is the most commonly used reverse-phase column in HPLC?

• C4 (butyl) column

• C8 (octyl) column

• Silica column

• C18 (octadecyl) column

Which of the following detectors is most commonly used in High-Performance Liquid Chromatography (HPLC)?

• Fluorescence detector

• Ultraviolet (UV) detector

• Refractive index (RI) detector

• Mass Spectrometry