本尼迪克特试验Benedict's reagent

柠檬酸根与 Cu²⁺ 配位，使其在碱性溶液中不沉淀为 Cu(OH)₂。还原糖的开链形式含醛基（或能异构化为醛的 α-羟基酮），被氧化为羧酸盐，同时 Cu(II) 被还原为 Cu(I)，生成 Cu₂O 沉淀。

Citrate chelates Cu²⁺ so it does not precipitate as Cu(OH)₂ in base. The open-chain form of a reducing sugar carries an aldehyde (or an α-hydroxy ketone that isomerises to one), which is oxidised to a carboxylate while Cu(II) is reduced to Cu(I), precipitating Cu₂O.

美国化学家斯坦利·本尼迪克特于 1908–1909 年提出，作为斐林试剂的改进：试剂稳定、可长期保存、碱性较弱。

Introduced by the American chemist Stanley Benedict in 1908–1909 as an improvement on Fehling's solution: it is stable, keeps well and is less strongly alkaline.

葡萄糖、果糖、麦芽糖、乳糖呈阳性；蔗糖（非还原糖）阴性，需先酸水解。曾广泛用于尿糖检测，现多被葡萄糖氧化酶试纸取代。

Glucose, fructose, maltose and lactose test positive; sucrose (non-reducing) is negative unless first hydrolysed by acid. It was long used for urine glucose and has largely been replaced by glucose-oxidase strips.