Development of a new method for tellurium analysis in environmental samples using different nanoparticles

In this study, a solid phase microextraction (SPME) approach based on two different magnetic nanoparticles was developed and optimized for the determination of trace levels of tellurium (Te). Oleic acid-modified magnetic iron oxide nanoparticles (OAMNPs) and MnFe₂(SiO₄)₂-based nanoparticles were used as adsorbents. Both systems were evaluated in combination with slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS). Parameters such as pH, buffer volume, nanoparticle amount, shaking mode and time, temperature, contact time and eluent volume were individually investigated and experimentally optimized. For the OAMNP adsorbent, the optimum conditions were pH 8.0, 1.0 mL buffer, 50 mg nanoparticles, 120 s manual shaking and 60 s contact time. Under these conditions, a LOD of 0.02 µg/L and a LOQ of 0.07 µg/L were obtained. The incorporation of the SQT increased the analytical sensitivity by approximately 9.1-fold compared to classical FAAS. For the MnFe₂(SiO₄)₂ nanoparticles, the optimum conditions were pH 5.0, 0.5 mL buffer, 75 mg adsorbent, 105 s vortex shaking and 60 s contact time. Under these conditions, LOD and LOQ values of 7.733 µg/L and 24.776 µg/L, respectively, were obtained. Selectivity was evaluated by interference studies in the presence of foreign ions, and recovery values were found to be in the range of 92–105%. In the analysis of commercial cold tea samples, Te levels were below the detection limit; however, after standard addition, recoveries ranged from 92–108%. In conclusion, the developed SPME–SQT–FAAS method offers a sensitive, selective and applicable analytical alternative for the determination of trace Te in complex environmental matrices using both types of nanoparticles.