A rapid, accurate, and ecofriendly pretreatment plays an extremely important role prior to ICP-MS for heavy metal analysis. In order to improve the pretreatment efficiency, a high-throughput and automatic magnetic solid-phase extraction of five heavy metals (Cd, Pb, Mn, Cu, and Zn) was carried out by a magnet-controlled pretreatment system with an ecofriendly diluted acid as an extracting agent and carboxyl-functionalized magnetic beads as a pretreatment material. Key conditions, including the pH, adsorption time, and eluent solution, were optimized. The time for purification and enrichment was only 8 min. The adsorption capacities of the carboxyl-functionalized magnetic beads were in the range of 152~426 mg g⁻¹. The preconcentration factor of Cu was 40, and others were 200. In the optimal conditions, the limits of detection for Mn, Zn, Cd, Cu, and Pb by ICP-MS were 3.84, 2.71, 0.16, 11.54, and 6.01 ng L⁻¹, respectively. The percentage recoveries were in the range of 80~110%, and the relative standard deviations were less than 3%. The developed method was in good agreement with traditional standard microwave digestion. Additionally, the designed system could simultaneously process up to 24 samples within 22 min, reducing the time to less than 1 min/sample. Thus, the proposed auto-MSPE-ICP-MS method was successfully applied to analyze five heavy metals in cereals and feeds with a simple operation and high precision, safety, and reliability.

A simple, rapid, sensitive, accurate, and automatic graphite furnace atomic absorption spectrometry (GFAAS) method for detecting Cd and Pb in cereals is presented. This method enables the simultaneous determination of Cd and Pb in cereals with a pre-treatment method of diluted acid extraction and a high-performance lead–cadmium composite hollow-cathode lamp (LCC-HCL), and it realizes automatic determination from sample weighing to result output through an automatic diluted acid extraction system. Under the optimization, Pb and Cd in cereals were simultaneously and automatically detected in up to 240 measurements in 8 h. The LOD and LOQ of this method were 0.012 and 0.040 mg·kg⁻¹ for Pb, and 0.0014 and 0.0047 mg·kg⁻¹ for Cd, respectively. The results of the four certified reference materials were satisfied; there was no significant difference compared with the ICP-MS method according to a t-test, and the RSDs were less than 5% for Cd and Pb. The recoveries of naturally contaminated samples compared with the ICP-MS method were favorable, with 80–110% in eight laboratories. The developed method is rapid, low-cost, and highly automated and may be a good choice for grain quality discrimination and rapid analysis of Cd and Pb in different institutions.

A rapid, simple, and accurate voltammetric method for quantifying total inorganic arsenic in rice was described in this work. The simplified sample pretreatment involved the addition of a mixed solution of nitric acid and L-cysteine, which facilitated the simultaneous extraction and speciation of arsenic (As(III)). To eliminate interference from complex rice matrices, magnetic composites were employed to absorb copper and other potential interference. Furthermore, As(III) was detected using linear stripping voltammetry with screen-printed electrodes modified in-situ with gold nanoparticles and L-cysteine, enhancing both sensitivity and selectivity. With this strategy, the methodology demonstrated good resistance to interference and high sensitivity, with a detection limit of 0.018 mg/kg. A comparative analysis between this method and liquid chromatography coupled with inductively coupled plasma mass spectrometry (ICP-MS) showed a good correlation with an R² of 0.995. Additionally, the method was successfully applied to determine total inorganic arsenic in commercial rice samples, yielding satisfactory results.