Magnetic N-doped porous carbon for analysis of trace Pb and Cd in environmental water by magnetic solid phase extraction with inductively coupled plasma mass spectrometry

Abstract

A novel magnetic N-doped porous carbon material (MNPC) was obtained by mixing urea, sucrose and Fe3O4@SiO2 and calcinating for carbonization. With g-C3N4 as intermediate template, the synthesized material has large BET surface area of 219.4 m2 g−1 and high nitrogen content of 9.4 wt%. With using MNPC material as sorbent, a new method by coupling magnetic solid phase extraction (MSPE) with inductively coupled plasma mass spectrometry (ICP-MS) was established for enrichment and determination of Cd(II) and Pb(II) in environmental waters. The conditions affecting MSPE were optimized including the effects of pH, sample volume, amount of sorbent usage, adsorption/desorption time and eluent type/concentration/volume. Under the optimized conditions, the developed MSPE-ICPMS method exhibited a good linear dynamic range of more than three orders of magnitude (2–5000 pg mL−1 for Cd(II) and 10–5000 pg mL−1 for Pb(II)) and a low detection limits of 0.49 and 3.1 pg mL−1 for Cd(II) and Pb(II), respectively. The relative standard deviations were in the range of 6.9%–7.3% for the target metal ions. The adsorption/desorption kinetics of the developed MSPE procedure was fast, and the total extraction procedure only cost 7 min (5 min for adsorption and 2 min for desorption) for each sample. The sorbent could be used for at least 5 times. The MSPE-ICPMS method has great potential for the determination of trace and even ultra-trace Cd(II) and Pb(II) in the environment waters.