Electrochemical studies of sodium borohydride in alkaline aqueous solutions using a gold electrode

Cyclic voltammetry using a gold disk working electrode has been employed for quantifying sodium borohydride in alkaline aqueous media. A 6 mm diameter disk working electrode is shown to offer higher sensitivity compared to a 1 mm diameter electrode, demonstrated by the slope of the calibration curve being 38 times greater when the 6 mm electrode is used. The dynamic range is also greater with the 6 mm electrode, evidenced by the square of the correlation coefficient for regression over the same concentration range. The influence of the matrix on the calibration curves was evaluated; 2 M NaOH, 2 M NaOH + 10% NaBO₂, 2 M NaOH + 20% NaBO₂, 2 M NaOH + 25% NaBO₂, and 25% NaBO₂ in solution at pH 12 were the matrices investigated. The matrix was shown to affect the calibration curves; generally, increasing content of NaBO₂ caused the slope to decrease. Cyclic voltammetry was then used to assess the stability of sodium borohydride in aqueous solutions of different compositions.