To predict the total antioxidant capacity of tumbo and camu–camu juices expressed as ascorbic acid equivalents (Eq.AA), first a mathematical prediction model was developed. Once the pulse voltammetry response for each ascorbic acid dilution was obtained, a PLS was applied for model development. To this end, two thirds of the ascorbic samples were used to develop and cross-validate the model, and the remaining third was employed to test it. Fig. 1 shows the adjustment between the real concentration values of ascorbic acid used to test the model and those obtained after employing the developed model. Table 2 shows that the obtained adjustment gave accuracy coefficients for the prediction (R2 = 0.998; RMSE = 0.219).