An easy and simple kilowatt-MPT-MS-based metal elements analysis method for rapid environmental water monitoring: An example from Poyang Lake of China

Abstract

A powerful analytical method based on microwave plasma torch/mass spectrometry (MPT-MS) was developed to rapidly detect mental elements in environmental water from Poyang lake in China. With minimum or uncomplicated sample manipulation, raw water samples were ionized by MPT for subsequent LTQ-MS analysis under negative ion mode. Typical potential contamination sources such (e.g., iron, cobalt, and nickel) were detected and identified by collision-induced dissociated (CID) experiment. It was found that the three metallic elements were formed as [M(NOx)mOn]−, which was universal; thus, they could be target ions. For the given elements, their limits of detection (LOD) were assessed as 0.09 μg•L−1 for iron ion, 0.03 μg•L−1 for cobalt ion, and 0.33 μg.L−1 for nickel ion under the optimized conditions; good determination coefficient (R2 ≥ 0.99) and the relative standard deviation (RSD, 2.0–11%, n = 11) were obtained. For current actual samples under testing, short analysis time for a single sample (less than 1 min), the average levels for iron, cobalt, and nickel, reached allowable concentrations of national standards, which also suggested this method is practically effective and usable. Moreover, possible ionization mechanism of metallic elements in MPT source was also discussed in this work, which may provide insight and useful information for the metal organics derived from water environment or metabonomics by MPT-MS. On the whole, this study lays a solid basis for the in-site mass spectrometry analysis of aqueous samples in relevant fields.

Keywords

• Microwave plasma torch
• Mass spectrometry
• Metallic elements
• Negative ion mode
• Mechanism
• Environmental water