Figure 6.

(A) Chromatograms of 25 µM BH₄ and BH₂ standards represented at oxidation potentials of 0, 150 and 280 for BH₄ (retention time 4.56 min) and at the oxidation potential of 280 mV for BH₂ (retention time 6.92 min). (B) Standard curves for BH₄ and BH₂ solutions, representing a linear range (BH₄: 0.3–125 µM, 13 concentration values; BH₂: 0.1–200 µM, 15 concentration values) with a linear regression correlation coefficient R² of 0.99 for both standards. Data are mean ± SD of n = 3 independent measurements per data point.