2.4. Atomic absorption spectrophotometer
An Analysengerate GmbH model 200A(Buck Scientific,
Germany) was used for metal determination, with
Cathodeon (England) hollow cathode lamps for Zn,
Mn, K, Mg, Ca; Buck Scientific hollow cathode lamps
of Cu, Na and Pb, and Fischer Scientific hollow cathode lamp for Fe, used as radiation sources. The elements
were measured under the optimum operating conditions
with an air-acetylene flame. Phosphorus levels of the
plant samples were determined by colorimeter at 630
nm.