Spectrophotometric flow-injection determination of total reducing sugars exploiting their alkaline degradation

An automated procedure exploiting alkaline degradation of carbohydrates is proposed for spectrophotometric determination of total reducing sugars, TRS (hydrolyzed sucrose plus reducing sugars), in samples relevant to the sugar industry. An environmental friendly reagent is used instead of the commonly used toxic (e.g. arsenate) or expensive (e.g. enzymes) reagents. The analytical steps of acidic sucrose hydrolysis and sugar alkaline degradation are in-line accomplished at about 95 °C. The formed colored solution is then spectrophotometrically monitored at 450 nm.The proposed system handles 60 samples per hour, and yields precise results, relative standard deviation being estimated as <5% for a typical sample (1.24%, w/v, TRS). Baseline drift has been not verified during 8-h working periods, emphasizing the system ruggedness. A linear response is observed between 0.1 and 2.0% (w/v) TRS. Results are in agreement with HPIC.