The determination of Cu2+, Fe3+, Zn2+ and Pb2+ in real samples by flame atomic absorption spectrometry after their separation- preconcentration on 2-(2-nitrophenylazo)- naphthalen-1-ol loaded on activated carbon

A sensitive and simple method for simultaneous preconcentration of trace heavy metal ions in some cereal and vegetable samples has been reported. The method is based on the adsorption of Cu2+, Fe3+, Zn2+ and Pb2+ on 2-(2-nitro-phenylazo)-naphthalen-1-ol (NPN) loaded on activated carbon (AC). The adsorbed metals on activated carbon were eluted using 3 ml 4 mol L−1 nitric acid. The influences of the analytical parameters including pH, flow rate of sample and eluent, type and concentration of eluent, amount of adsorbent and sample volume were investigated. The effects of matrix ions on the recoveries of analyte ions were also investigated. The recoveries of analytes were generally higher than 95%. The detection limits for Cu2+, Fe3+, Zn2+ and Pb2+ were 0.17 μg L-1 , 0.16 μg L-1 ,0.11 μg L-1 and 0.12 μg L-1 respectively.