Screening Analysis for Hazardous Heavy Metals in Foods and Food Additives using Energy Dispersive X-ray Fluorescence Spectrometer

Importance of the Topic

The control of hazardous heavy metals in foods and additives is critical for public health and safety. Traditional methods like atomic absorption spectrophotometry require acid digestion of samples and specialized training. Energy dispersive X-ray fluorescence offers direct analysis without dissolution, reducing preparation time and contamination risks while supporting high throughput.

Objectives and Study Overview

This study evaluates the performance of the Shimadzu ALTRACE energy dispersive X-ray fluorescence spectrometer in screening for toxic metals. Three applications were examined: cadmium determination in rice, simultaneous analysis of cadmium arsenic and lead in milk, and arsenic and lead quantification in various food additives.

Methodology and Instrumentation

The ALTRACE system uses a rhodium target X-ray tube optimized to 50 kV for arsenic and lead and 65 kV for cadmium with automatic current control. A silicon drift detector captures characteristic fluorescent X-rays. Calibration was performed with four concentration standards using scatter correction for sample shape and matrix and overlap correction for coexisting elements. Samples were loaded into polypropylene film cells (5 μm thickness) and slightly compressed; citric acid samples were also crushed to ensure uniform grain size.

Main Results and Discussion

The lower limits of detection reached sub ppm ranges, with cadmium and arsenic at 0.08 μg/g and lead at 0.10 μg/g. In rice reference material cadmium was measured at 0.532 μg/g with a standard deviation of 0.050 and coefficient of variation below 10 percent. Milk samples showed all target metals below quantitation limits (<0.21 μg/g Cd, <0.28 μg/g As, <0.23 μg/g Pb). Food additives including adipic acid vitamin C and citric acid yielded arsenic and lead levels under 0.25 μg/g. Repeatability tests over ten replicates confirmed precision with variation under 0.3 percent.

Benefits and Practical Applications of the Method

The direct solid analysis eliminates time consuming acid digestion and potential reagent contamination. The high sensitivity and optimized optics allow rapid screening of up to 48 samples continuously improving laboratory throughput. This makes the ALTRACE a viable alternative to conventional absorption spectroscopy for routine quality control and safety monitoring in the food industry.

Future Trends and Applications

Future developments may integrate automated sample handling with robotics for unattended screening. Expansion of detectable element range and enhancements in portable XRF technology could enable on site testing in processing facilities and supply chains. Coupling with data analytics platforms may support real time trend monitoring and predictive risk assessment.

Conclusion

The Shimadzu ALTRACE EDXRF spectrometer demonstrates significantly improved sensitivity for heavy metal screening in food matrices combined with simplified sample preparation and high throughput. Its performance positions it as a practical tool for ensuring food safety and compliance with regulatory standards.

References

1. Standards and criteria for food and food additives notification No 370 Ministry of Health and Welfare 1959
2. Public Health Bureau Food Safety Standards and Evaluation Division Notification No 0308-1 March 8 2024
3. Japan's Specifications and Standards for Food Additives 10th Edition
4. Codex General Standard for Contaminants and Toxins in Food and Feed CODEX STAN 193-1995