Microplasma-induced vapor generation for rapid, sample preparation-free screening of mercury in fruits and vegetables

Abstract

A method for the rapid screening of toxic elements in fruits and vegetables is of significant importance to prevent human exposure to these elements. In this work, a simple method used for microplasma-induced vapor generation (μPIVG) was developed for the rapid screening and quantification of mercury in fruits and vegetables without sample preparation. A stainless-steel capillary was partly inserted into a juice droplet from the tested fruits and then the sample liquid automatically moved to the end of the capillary with the assistance of inherent capillary driving force. Subsequently, a high voltage was applied between the capillary and a tungsten electrode to generate microplasma wherein the juice was sprayed and the mercury ions contained in the juice were converted to mercury cold vapor (Hg⁰). The Hg⁰ was finally separated from the liquid phase and swept to an atomic fluorescence spectrometer (AFS) for rapid screening. A standard addition method coupled with μPIVG atomic fluorescence spectrometry was further used for the quantitative analysis of the suspected sample. Under the optimized conditions, the limits of detection (LODs) of 0.3, 0.5, and 0.4 μg L⁻¹ were obtained for the tested tomato, lemon, and orange samples, respectively. The proposed technique provides a simple and cost-effective tool for the rapid screening of mercury in fruits and vegetables by atomic spectrometry.