FEHLING’S B Reagent

500mL

Fehling’s B Reagent is an alkaline solution of potassium sodium tartrate, formulated with sodium hydroxide, and used in conjunction with Fehling’s A Reagent for the qualitative detection of reducing sugars. The tartrate acts as a complexing agent, stabilising copper(II) ions in alkaline medium and preventing premature precipitation. When mixed with Fehling’s A, the combined reagent enables the reduction of Cu²⁺ to cuprous oxide (Cu₂O), resulting in a characteristic brick-red precipitate. Fehling’s B Reagent is widely used in analytical chemistry, food analysis, pharmaceutical testing, and teaching laboratories.