Screening Analysis for Hazardous Heavy Metals in Foods and Food Additives

Significance of the Topic

Ensuring the absence of toxic heavy metals such as cadmium, arsenic and lead in foods and additives is vital for consumer health. Conventional atomic absorption methods require complex sample digestion, whereas energy dispersive X-ray fluorescence (EDXRF) enables direct analysis of solids, simplifying preparation and reducing analysis time.

Study Objectives and Overview

This study evaluates the performance of Shimadzu’s ALTRACE EDXRF spectrometer for high-sensitivity screening of cadmium in rice and arsenic and lead in food additives. The goal is to demonstrate improved detection limits, analysis throughput, and user-friendly operation for routine food safety testing.

Methodology and Instrumentation

• Instrumentation: ALTRACE spectrometer equipped with a rhodium-target X-ray tube, a silicon drift detector (SDD), and optimized optics for enhanced sensitivity.
• Calibration: Standard solutions for Cd, As and Pb at 0, 0.5, 1 and 5 µg/g; corrections for sample shape, matrix effects, and inter-element overlap.
• Sample Preparation: Powdered or crushed samples (rice, adipic acid, vitamin C, citric acid) compressed in a polypropylene-film cell without acid digestion.
• Analysis Conditions: Tube voltage 65 kV for Cd and 50 kV for As/Pb; automatic tube current; primary filters (#1 for Cd, #5 for As/Pb); air atmosphere; 300 s counting time; maximum 40% dead time.

Main Results and Discussion

• Detection Limits: 0.08 µg/g for Cd and As, and 0.10 µg/g for Pb based on theoretical 3σ criteria.
• Calibration Performance: Standard deviation of 0.037 µg/g for CdKα, 0.030 µg/g for AsKα, and 0.066 µg/g for PbLβ1.
• Repeatability: Ten-repeat measurement of 0.548 µg/g Cd in rice yielded a relative standard deviation of 9.4%.
• Quantitative Screening: As and Pb levels in various additives were below quantitation limits (<0.17–0.28 µg/g), meeting regulatory thresholds for food additives.

Benefits and Practical Applications

• High sensitivity with no need for acid digestion, preserving sample integrity.
• Ability to process up to 48 samples continuously increases laboratory throughput.
• Simple sample prep and rapid analysis support routine compliance monitoring and QA/QC in the food industry.

Future Trends and Potential Applications

Advances in EDXRF detector technology, automation and data processing are expected to further lower detection limits and enable expanded multi-element screening in diverse matrices. Integration with laboratory information systems and high-throughput workflows will enhance trace metal surveillance across the food supply chain.

Conclusion

The ALTRACE EDXRF spectrometer offers a sensitive, high-throughput solution for screening cadmium, arsenic and lead in foods and additives without complex sample digestion. Its performance and ease of use make it a valuable tool for regulatory labs and industrial QA/QC.

References

1. Ministry of Health and Welfare notification No. 370 (1959): Standards and criteria for food and food additives.
2. Public Health Bureau Food Safety Standards Division notification No. 0308-1 (2024).
3. Japan Specifications and Standards for Food Additives, 10th Edition.
4. CODEX STAN 193-1995: General standard for contaminants and toxins in food and feed.