A Shimadzu (Kyoto, Japan) Model AA-670G atomic absorption
spectrometer equipped with a GFA-4A graphite furnace atomizer
and deuterium lamp background correctionwas employed. Amanganese
hollow cathode lamp (Hamamatsu photonics K.K., Japan)
was used as the radiation source. The operating conditions of the
hollow cathode lamp were those recommended by the manufacturer.
Pyrolytically coated graphite tubes were used throughout.
Argon 99.999% (Roham gas Co. Tehran, Iran), with 1.5 Lmin−1 flow
rate, was used as a protective and purge gas. The detailed graphite
furnace temperature program used for the determination of Mn is
shown in Table 1.