Calibration graphs and detection limit
A calibration curve was constructed for copper in the
range of 0.1-10.0 mg/l of copper at 290.5 nm according to the
general procedure described above. The calibration graph
can be represented by a linear regression equation:
y = 0.1047x + 0.0086 (r
2
= 0.999)
(y = absorbance, x = concentration).
The detection limits based on three times the standard
deviations of the blank were 10 g/l (N = 21). The relative
standard deviations for the copper determinations were 2%
(N = 10) at 0.5 mg/l Cu(II).