Page 71 - Modern Derivatization Methods for Separation Sciences

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vitamin C, the difference between total vitamin C and AA is calculated in order to measure DHAA by
measurement of AA solely without reduction. Simultaneous determination of 3-(1,2-dihydroxyethyl)
furo[3,4-b]quinoxaline-1-one (DFQ) and AA was developed using the reaction of o-phenylenediamine
(OPDA) and DHAA to form fluorescence derivatives, DFQ [122]. A variant method includes
oxidization of AA to DHAA with Norit, fluorescent derivatization to DFQ (λex350 nm, λem430 nm)
and separation on reversed-phase column and detection as total vitamin C [123].

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