2.2. Materials and reagents
De-ionized water was obtained from the purification via
cation and anion exchange resin columns, the conductivity
of the de-ionized water was less than 4 lS cm1. All glassware
(borosilicate) and plasticware (low density polyethylene,
LDPE) were soaked in 2% (v/v) HCl for 2 h, rinsed
with de-ionized water, soaked in 2% (v/v) HNO3 for 2 h,
and then rinsed with de-ionized water several times.
All reagents were standard analytical grade and used
without further purification. De-ionized water was used
for all preparation of solutions. Acid solutions (Lab Scan)
were prepared using volumetric glassware. Working standard
metal solutions were prepared from stock solutions
of 1000 mg L1 (BDH Laboratory Supplies) by diluting
to the required concentration by 1% (v/v) HNO3.