Which method is used to separate and quantify catecholamine metabolites such as HVA and VMA in urine?

• A. HPLC
• B. Gel electrophoresis
• C. ELISA
• D. PCR

Answer: (A)

Concentrating on separation and accurate measurement of small urinary metabolites requires a method that resolves closely related compounds in a complex liquid sample. High-performance liquid chromatography does this by passing the urine extract through a column where each compound interacts differently with the stationary phase and mobile phase. HVA and VMA, being small catecholamine metabolites, elute at different times, producing distinct peaks that can be quantified with a suitable detector (often electrochemical or UV). This setup is sensitive enough to measure the metabolites at the low concentrations found in urine and handles the urine matrix well, especially when prep steps and internal standards are used.

Gel electrophoresis separates molecules mainly by size and charge and is more suited to large biomolecules like proteins or nucleic acids, not small metabolites. ELISA relies on specific antibodies, which is feasible for certain targets but not as straightforward or universal for small catecholamine metabolites, and PCR targets nucleic acids, not small organic compounds.