Determination of Arsenic Species in Apple Juice by LC-ICP-MS Analysis

Importance of the topic

Arsenic occurs ubiquitously in the environment in multiple chemical forms with widely varying toxicities. Speciation analysis is critical because inorganic arsenite and arsenate pose greater health risks than organic species. Regulatory bodies such as the U.S. FDA have set action levels for inorganic arsenic in food and beverages, making sensitive and selective analytical methods essential for food safety assessments.

Objectives and overview of the study

This application note demonstrates the use of an LC-ICP-MS system to separate and quantify six arsenic species in apple juice. The study aims to validate method sensitivity, accuracy, and compliance with FDA action limits through spiked recovery experiments and detection limit assessment.

Methodology and instrumentation

Sample pretreatment involved acidification with phosphoric and nitric acids followed by dilution. Chromatographic separation employed a Shimadzu Nexera HPLC with a Sigma-Aldrich Discovery HS F5 column and formic acid–methanol mobile phase containing tetramethylammonium hydroxide. The LC was coupled on-line to a Shimadzu ICPMS-2040/2050 mass spectrometer controlled by LabSolutions ICPMS TRM software. Key ICP-MS settings included 1.2 kW RF power, helium collision gas, and a cooled cyclone chamber.

Main results and discussion

The method achieved baseline separation of arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, and arsenocholine in under six minutes. Detection limits (3σ) were below 0.04 µg/L for all species. Spike recovery rates ranged from 101 % to 106 %, demonstrating excellent accuracy. Analysis of apple juice showed inorganic arsenic concentrations well below the FDA action level of 10 µg/kg, confirming product safety.

Benefits and practical applications

• High sensitivity and selectivity for trace-level arsenic speciation.
• Integrated LC-ICP-MS workflow streamlines method setup and data analysis.
• Comprehensive method package reduces development time and ensures reproducibility.
• Applicable to routine food safety monitoring and regulatory compliance.

Future trends and applications

Advances may include:

• Expanding speciation panels to emerging arsenic compounds.
• Automated sample prep and data processing to enhance throughput.
• Portable or miniaturized hyphenated systems for on-site testing.
• Integration with chemometric and AI tools for deeper insight into complex matrices.

Conclusion

The LC-ICP-MS approach provides a robust, accurate, and efficient tool for arsenic speciation in food matrices, delivering results that support regulatory compliance and consumer safety. The method’s sensitivity and ease of use make it well suited for routine laboratory applications.

References

1. U.S. FDA. FDA Issues Final Guidance to Industry on Action Level for Inorganic Arsenic in Apple Juice. June 8, 2023.
2. U.S. FDA. Guidance for Industry: Action Level for Inorganic Arsenic in Apple Juice. June 8, 2023.