The model of single moving redox boundary (MROB) was proposed for development of electrophoresis titration this year (H.Y.Xie,et al.,Analyst 138 (2013) 1137).However,one faces great difficulty to use a single MROB for titration analysis of a model analyte without color change during redox (e.g.,ascorbic acid).Herein,a novel model of double-MROB electrophoresis,including its mechanisms,equations and procedures,was developed for titration analysis of ascorbic acid content in chewable vitamin C tablet.The first MROB was created with ferric iron (Fe3+) and iodide ion (I-) in which Fe3+ was deoxidized as Fe2+ and I- was oxidized as molecular iodine (I2) used as indicator of visible MROB due to blue starch-iodine complex.The second redox boundary was then formed between the molecular iodine and target analyte of ascorbic acid.The experimental conditions were optimized for the double-MROB.Under optimized conditions,there was a quantitative relationship between velocity of MROB and ascorbic acid concentration in the double-MROB system.Finally,the titration of ascorbic acid in chewable vitamin C tablet was performed by the MROB method,the titration results were in agreement with those via the classic iodometric titration.The relevant RSD values of intra-day and inter-day were less than 5.55% and 6.64%,respectively.All of the results implied that the developed method had potential use in quantitative analysis of redox-active species in biomedical sample..