Simultaneous determination of iron and zinc by pH gradient construction in a flow-injection system

A flow-injection method for the simultaneous determination of iron and zinc in the human hair with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) using a pH gradient technique has been developed. The linear range for the determination of iron is 0.1 approximately 1.8 mug ml(-1) and for zinc is 0.2 approximately 5.0 mug ml(-1). About 20 approximately 30 samples can be determined in 1 h. The proposed method is simple, rapid and accurate. It has been applied to the simultaneous determination of trace amounts of iron and zinc in the human hair with satisfactory results.