Surface-functionalized palladium nanoparticles as chemical modifier for cadmium determination by graphite furnace atomic absorption spectrometry

Cadmium determination in environmental samples by graphite furnace atomic absorption spectrometry (GF AAS) can be limited by matrix effects and analyte volatility. In this work, 3-mercaptopropionic acid-functionalised palladium nanoparticles (MPA-Pd-NPs) were evaluated as chemical modifier and compared with the conventional palladium/magnesium (Pd/Mg) system. In natural water, MPA-Pd-NPs provided higher integrated absorbance than Pd/Mg at lower pyrolysis temperatures, whereas Pd/Mg maintained a more stable response over a broader range. Under optimised conditions for MPA-Pd-NPs (700°C pyrolysis and 1,400°C atomisation), the calibration slopes were 0.10239 and 0.10666 L µg−1 s−1 for MPA-Pd-NPs and Pd/Mg, respectively, corresponding to a difference of approximately 4%. The method provided a limit of detection (LOD) of 0.01 µg L−1, a limit of quantification (LOQ) of 0.04 µg L−1 and a relative standard deviation (RSD) below 3%. Recovery tests at 3, 5 and 7 µg L−1 yielded recoveries from 96 to 111%. The results agreed with those obtained by inductively coupled plasma mass spectrometry (ICP-MS), and the analysis of water reference materials further confirmed the accuracy of the proposed method (paired t-test, p > 0.05). These results show that surface-functionalised Pd nanoparticles can deliver analytical performance comparable to that of conventional Pd/Mg while exhibiting a distinct thermal profile.