To validate the barcode assay approach, we have directly
compared with the standard spectrophotometry method.
Fig. 5c depicts the color intensity as a function of the absorbance
for each of the standard solutions tested; the linear
relationship (R2 = 0.966), with the exception of the blank, illustrates
the direct correlation between color intensity and absorbance.
This result not only confirms the accuracy of the
colorimetric protocol but also constitutes the validated calibration
curve (Fig. 2b) for the analysis of unknown samples
(vide infra).