The pH of sample solution is an important parameter for
metal-chelate formation and its extraction. Thus, the influence
of pH over the range of 3–9 on the Ag(I)–MBI complex formation
and the Ag(I) extraction was investigated. The pH was
adjusted by addition of appropriate amount of HNO3 and NaOH.
The results shown in Fig. 2 indicated that the maximum
absorbance was obtained at pH 5–6; therefore, pH 5.5 was
used throughout the study. The optimum pH of sample solution
can be adjusted using acetate/acetic acid buffer at pH 5.5.
Hence, 1 mL of acetate buffer, pH 5.5, was added to the sample
solutions to maintain the pH at optimum value.