Highly Sensitive Determination of Cadmium by Atomic Emission Spectrometry with Miniaturized Solution Anode Glow Discharge

A solution anode glow discharge (SAGD) was established as a miniaturized excitation source of atomic emission spectrometry (AES) for the detection of Cd in rhizosphere soil, carrot, and carrot leaf samples. The working conditions, such as electrolyte pH, discharge voltage, support electrolyte, solution flow rate, and discharge distance, were systematically optimized. The effect of 31 foreign ions on the Cd determination was investigated. In addition, the influences of matrix modifiers on the Cd signal intensity and interference elimination were examined in detail. The results showed that under the optimal operating parameters, the presence of Fe³⁺, Co²⁺, Pb²⁺, Cu²⁺, Cr³⁺, and Tl³⁺ ions at 30 mg/L causes severe depression effects for the detection of Cd, and adding ascorbic acid as a matrix modifier can reduce the matrix interference, improve sensitivity, and lower the limit of detection (LOD). The LOD of Cd is 4.4 μg/L, and power is below 8 W using SAGD without any matrix modifier. Compared with the solution cathode glow discharge–atomic emission spectrometry (SCGD-AES), the sensitivity is improved about 11-fold, and the power is consumed only about one-sixth. The analysis results of SAGD-AES are in agreement with the Cd-certified reference material and verification values measured by inductively coupled plasma atomic emission spectroscopy, suggesting that proposed method has high accuracy and reliability.