Determination of thallium by solution anode glow discharge atomic emission spectrometry with an interference filter for spectral discrimination

Abstract

A novel, cost-effective solution anode glow discharge atomic emission spectrometry system with an interference filter (SAGD-IF-AES) is reported for the determination of trace thallium (Tl) in water. The system integrates a SAGD excitation source with a low-cost interference filter as a compact spectral discrimination device, addressing the limitations of conventional bulky and expensive spectrometers. Key operational parameters, including solution flow rate, pH, discharge gap, and current, were systematically optimized. Under the optimal conditions (3.6 mL min⁻¹, pH = 2, 2 mm gap, and 60 mA current), the system achieved a low detection limit of 0.53 µg L⁻¹ for Tl with excellent linearity (R² > 0.999) and high precision (RSD of 1.1%). This performance, comparable in order of magnitude to that of spectrometer-based SAGD-AES, confirms the feasibility of the filter-based approach. However, significant signal suppression from common matrix ions (Na⁺, K⁺, Ca²⁺, and Mg²⁺) was observed, indicating a challenge for the direct analysis of complex samples. The method's accuracy was validated using a certified reference material, yielding satisfactory recoveries of 95–105%. This work provides a technical pathway toward developing portable analytical devices for on-site heavy metal monitoring.