Flow injection turbidimetric determination of total organic carbon with a gas-liquid transfer microreactor

A procedure for the determination of total organic carbon (TOC) and its fra ctions in industrial effluent samples is proposed. A flow injection system using a gas-liquid transfer microreactor was developed, and adapted to a tu rbidimetric spectrophotometer. Samples were decomposed into glass vials in a microwave oven and a fraction of the CO2 was injected into a carrier gas and pumped to a glass microreactor. This device was specially developed to assure a quantitative reaction with a barium hydroxide solution. The result ing suspension was removed from the microreactor and pumped to the flow cel l and the transient signal was recorded. With minor modifications, the syst em allows the determination of different carbon fractions. The advantages o f the proposed procedure are simplicity, low volume of samples and reagents , high frequency of determinations and low cost. The dynamic range is 20-80 0 mg C l(-1), and the calculated LOD (n = 10, confidence level 99.7%) is 17 mg C l(-1). The maximum analytical frequency was 120 determinations per ho ur. Compared to a reference method for TOC determination, no significant di fferences (t-test), were observed. (C) 2001 Elsevier Science B.V. All light s reserved.