Selective detection of trace lead in lead-free solder alloy by flow injection on-line solid-phase extraction using a macrocycle immobilized silica gel as sorbent coupled with hydride generation atomic fluorescence spectrometry

Abstract

As lead-free solder is a tin-based alloy, and contains large amounts of tin, copper or other metals that can cause serious interferences with hydride generation, accurate determination of trace lead in lead-free solder by hydride generation atomic fluorescence spectrometry (HG-AFS) is challenging. In this work, a flow injection (FI) on-line solid phase extraction (SPE) technique was coupled to HG-AFS for selective determination of lead in lead-free solder. Macrocycle immobilized silica gel with high selectivity for lead was employed as the sorbent to eliminate interferences from other heavy metals and hydride-forming elements on HG-AFS determination of lead. At least 500 mg L⁻¹of Cu(II), Fe(III), Ni(II), Zn(II), Cr(II), Ca(II), Al(III), Cd(II), Co(II) and Ag(I), 200 mg L⁻¹ of Sn(II), 100 mg L⁻¹ of As(III), Hg(II), Se(IV) and Sb(III), and 50 mg L⁻¹ of Ba(II) had no interferences on the determination of 0.5 μg L⁻¹ Pb(II). With a sample loading flow rate of 4.8 mL min⁻¹ for 60 s on-line SPE, a detection limit (3s) of 3 ng L⁻¹ and an enhancement factor of 61 was obtained. The precision (RSD, n = 11) was 1.8% at the 0.5 μg L⁻¹ Pb(II) level. The developed method allows cost-effective, sensitive, accurate and interference-free determination of trace lead in lead-free solder samples.