Flow injection spectrophotometric determination of reducing sugars using afocalized coiled reactor in a domestic microwave oven

A flow injection (FI) spectrophotometric procedure for determining reducing sugars content in sugar cane juices using a focalized PTFE coiled reactor positioned at the output antenna of a domestic microwave oven at 700 W is p roposed. In this system, sample solution converge to 1.0 mol l(-1) NaOH and 5.2 mmol l(-1) K3Fe(CN)(6) solutions previously mixed and the decrease of hexacyanoferrate(III) concentration was monitored at 420 nm. Under best ana lytical conditions, there was a direct relationship between absorbance decr ease and reducing sugar content (fructose plus glucose concentrations) in t he concentration range from 50 to 1200 mu mol l(-1) with a detection limit of 15 mu mol l(-1). The relative standard deviations (rds) were less than 1 .4% for ten injection of 400 and 800 mu mol l(-1) fructose solution and the analytical frequency was 70 h(-1). A. paired t-test showed that all result s obtained for sugar cane juices using this FI procedure and the Somogyi-Ne lson batch procedure agree at the 95% confidence level. (C) 1999 Elsevier S cience B.V. All rights reserved.