Ultratrace Pb determination in seawater by solution-cathode glow discharge-atomic emission spectrometry coupled with...

A novel method for the determination of ultratrace Pb in seawater by solution-cathode glow discharge atomic emission spectrometry (SCGD-AES) coupled with hydride generation (HG) has been developed. In the SCGD process, the hollow Ti tube, which can introduce gas instead of a solid tungsten rod is used as a discharge anode and combined with hydride generator. HG technology can not only separate Pb from a seawater matrix and reduce the matrix interference on detection, but can also significantly improve the transfer and atomization efficiencies for SCGD-AES. The optimum working conditions for HG and SCGD-AES for quantitative analysis of Pb were determined as 1% H₂C₂O₄ as the masking agent and addition of 3% formic acid to increase Pb volatilization. The limit of detection (LOD) for Pb was decreased by two orders of magnitude in comparison to the SCGD-AES process alone. Under optimal conditions, the LOD for Pb was 0.17 μg L^-1, and the relative standard deviation was 2.1% (n = 11) for 100 μg L^-1 Pb in artificial seawater. The proposed quantification method was verified using a seawater reference material (BWQ7001-2016), and the obtained results agreed well with certified values. Finally, the approach was used to quantitatively analyse Pb in seawater, and the results agreed well with those obtained by inductively coupled plasma mass spectrometry. The recoveries of standard addition were between 96.0% and 103.0%.