Oxidation—continued with potassium ferricyanide

Typical FI A manifolds are shown in Fig. 13.10 with two general alternatives depending on whether injection takes place before or after the continuous extractor device. The most common situation is when prior injection of the sample take place. Figure 13.10(a) depicts a manifold for the determination of vitamin Bi in pharmaceuticals [178], based on the oxidation of thiamine to thiochrome in a carrier of potassium ferricyanide in a basic medium (NaOH). The thiochrome is continuously extracted into a chloroform stream and the fluorescence of the organic phase is measured continuously. 

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