The calibration curve used for the determination
of copper in tea samples by FAAS was established
using the following procedure. An appropriate
amount of working standard solution of copper and
5 ml of 2 M HCl were transferred to a 100-ml
volumetric flask and diluted with double-distilled water.
The calibration solutions were prepared over
the concentration range 0.05–1.6 µg ml–1 Cu. For
the determination of copper in tea leaves, 1 g of
the oven-dried (105 °C) sample was preheated for
0.5 h at 250 °C and burned for 1 h at 800–850 °C.
The obtained ash was wetted with double-distilled
water, mixed with 10 ml of diluted HCl (1:1), the
mixture was mildly boiled, cooled to room temperature,
filtered (if necessary), transferred to a 25-ml
volumetric flask and diluted with double-distilled water