Table 4.

Recoveries of Pb, Cd and As heavy metals added to henna and walnut tree bark samples.

Heavy Metal	Slope			% Recover
	Standard Solution	Henna	Walnut Tree Bark	Henna	Walnut Tree Bark
Pb	2555.6	2563.0	2500.3	100.3	97.8
Cd	1699.2	1692.5	1669.3	99.6	98.2
As	1374.5	1375.8	1372.1	100.1	99.8