A Shimadzu 680 AA, atomic absorption spectrometer equipped with deuterium
background corrector (Shimadzu, Japan) equipped with a hollow cathode lamp and
a deuterium background corrector at respective wavelengths using an air-acetylene
flame was used. The instrument parameters were set according to those recommended
by the manufacturer.
A Metrohm 691 pH/Ion meter (Switzerland, Swiss) with a combined glass–calomel
electrode was used for the adjustment of the pH of the test solution.