Simultaneous Analysis of Trace and Major Elements in Rice by ICPE-9820

Importance of the Topic

Rice is a primary food source worldwide, especially in Asia, and its nutritional profile—including proteins, lipids, vitamins, minerals, and dietary fiber—makes it vital for health. However, environmental contamination, particularly with toxic metals such as cadmium (Cd), poses significant health risks. Ensuring both beneficial and harmful elements are monitored accurately in rice supports food safety, regulatory compliance, and public health.

Objectives and Study Overview

This work demonstrates the simultaneous determination of major elements (e.g., potassium, phosphorus) and trace toxic elements (e.g., cadmium) in brown rice using the Shimadzu ICPE-9820 inductively coupled plasma atomic emission spectrometer (ICP-AES). The instrument’s dual-view capability (axial and radial) enables high-sensitivity measurement of trace elements and accurate quantification of high-concentration elements in a single analysis.

Methodology and Sample Preparation

Brown rice powder standard samples (NIES No.10-a, ‑b, ‑c) were weighed (0.4 g) and digested with a mixture of 4.5 mL nitric acid and 0.5 mL hydrochloric acid in a microwave digestion system. After cooling, digests were diluted to 20 mL with distilled water and used for analysis. Quantitative determinations were performed by calibration-curve methodology.

Used Instrumentation

The Shimadzu ICPE-9820 ICP-AES was operated under the following conditions:

• Radio frequency power: 1.2 kW
• Plasma gas flow rate: 10 L/min
• Auxiliary gas flow rate: 0.6 L/min
• Carrier gas flow rate: 0.7 L/min
• Sample introduction: Nebulizer with cyclone mist chamber
• Plasma torch: Mini Torch
• Observation modes: Automatic axial (AX) and radial (RD) view switching

Calibration curves for elements such as K were established up to 200 mg/L, showing excellent linearity (r=0.99999) in both views.

Main Results and Discussion

Trace cadmium was measured with high sensitivity in axial mode, while major elements (K, P) were quantified accurately in radial mode. Analysis of NIES standard rice powders yielded element concentrations closely matching certified values. Cadmium levels in all samples remained below the regulatory limit of 0.4 mg/kg, indicating low contamination. Other elements (Al, Ca, Cu, Fe, Mn, Mo, Pb, Zn) also showed strong agreement with reference data.

Benefits and Practical Applications of the Method

• Simultaneous multi-element analysis reduces sample handling and analysis time.
• Wide dynamic range accommodates both high and trace concentrations in a single run.
• Automated view switching ensures optimal sensitivity and accuracy without manual adjustment.
• Suitable for routine quality control of rice and other food products to meet safety standards.

Future Trends and Potential Uses

The dual-view ICP-AES approach can expand into high-throughput screening of diverse food matrices, environmental samples, and biological tissues. Integration with automated sample preparation systems and advanced data analysis software will further enhance throughput and robustness. Emerging applications include speciation studies, nano-particle analysis, and real-time monitoring of contaminants in agricultural products.

Conclusion

The Shimadzu ICPE-9820, with its axial/radial auto-switching capability, provides a reliable, efficient platform for simultaneous quantification of both major nutrients and trace toxic elements in brown rice. The method delivers accurate, reproducible results that support food safety assessments and regulatory compliance.

References

• CODEX GENERAL STANDARD FOR CONTAMINANTS AND TOXINS IN FOODS (CODEX STAN 193-1995, Rev. 3-2007)