Magnetite-based SPME-SQT-FAAS for trace chromium determination in rice

Rice, an essential carbohydrate and nutrient source grown in aquatic environments, is a staple food globally. Due to the high toxicity of chromium (Cr), monitoring its trace levels in agricultural products is critical for human health. In this study, Total Cr concentrations were determined in two distinct rice varieties: Karacadağ rice (Turkey) and Baldo rice (Italy). A novel Magnetic Solid-Phase Extraction (MSPE) protocol using oleic acid-coated magnetic nanoparticles (OAMNPs) was developed and coupled with slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) for trace chromium quantification. Following systematic optimization of key operational parameters such as sample pH, eluent and buffer volumes, and magnetic nanoparticle (MNP) dosage, the method yielded a limit of detection (LOD) of 1.30 µg/L, a limit of quantification (LOQ) of 4.33 µg/L, and a linear range of 5–100 µg/L (R 2 = 0.9989), delivering a remarkable enhancement factor of 104.78. High precision was confirmed with a relative standard deviation (RSD) of 5.78%. The method demonstrated excellent accuracy and robustness, supported by recovery values ranging between 93 and 105% in the presence of common interfering ions. These quantitative outcomes underscore that the developed analytical platform is highly sensitive, precise, and efficient for monitoring trace chromium in complex food matrices. Methodological accuracy and robustness were successfully validated through recovery assays. These outcomes underscore that the proposed OAMNP- MSPE-SQT-FAAS framework represents a highly sensitive, precise, and efficient analytical platform for detecting trace chromium within complex matrices.