Hydrochlorothiazide is a thiazide diuretic often considered the prototypical member of the class. It reduces the reabsorption of electrolytes from the renal tubules. This results in increased excretion of water and electrolytes, including sodium, potassium, chloride, and magnesium. It is used in the treatment of high blood pressure and swelling due to fluid build-up as well as several disorders such as edema, hypertension, diabetes insipidus, and hypoparathyroidism. Primesep 200, a reverse phase column, contains embedded acidic ionizable groups and can retain Hydrochlorothiazide. The method is UV compatible and can be used as a general approach for analyzing similar compounds.