Question

Which of the following detectors does not require the presence of chromophore in HPLC analysis?

• A. \( \text{Fluorescence} \)
• B. \( \text{Photo diode array} \)
• C. \( \text{Evaporative light scattering} \)
• D. \( \text{UV} \)

Hint:

Think of ELSD as "seeing the mist" – it detects what's left after the solvent evaporates, regardless of its color (chromophore).

Answer 1

The Correct Option is C

A chromophore is a part of a molecule that absorbs light at a particular wavelength, giving rise to color. Many HPLC detectors rely on the presence of a chromophore in the analyte for detection. - UV detectors detect analytes that absorb ultraviolet light, which requires the presence of a chromophore. - Fluorescence detectors detect analytes that exhibit fluorescence after excitation with light, which also requires specific structural features (fluorophores). - Photo diode array (PDA) detectors are essentially UV-Vis detectors that can simultaneously monitor absorbance over a range of wavelengths, thus still requiring a chromophore for UV or visible absorption. - Evaporative light scattering detectors (ELSD), however, do not rely on the optical properties of the analyte. Instead, they nebulize the eluent, evaporate the mobile phase, and then detect the non-volatile analytes by measuring the light scattered by the resulting particles. Therefore, ELSD can detect a wide range of compounds, including those lacking a chromophore.