Fast Determination of Inorganic Arsenic (iAs) in Food and Animal Feed by HPLC-ICP-MS

Significance of the Topic

Inorganic arsenic (iAs) species, arsenite and arsenate, pose significant health risks due to their high toxicity compared with organic arsenic forms. Regulatory bodies worldwide, including the European Union, have established maximum allowable levels of iAs in food and animal feed to protect human and animal health. Rapid and reliable analytical methods are essential for routine monitoring to ensure compliance with these regulations and to safeguard public health.

Objectives and Study Overview

This work aimed to develop and validate a fast, robust HPLC-ICP-MS method for the determination of inorganic arsenic in a range of food and feed matrices. The method was designed to comply with EU Regulation 1881/2006 and Directive 2002/32/EC, as well as with the requirements of CEN standards EN16802:2016 (food) and prEN17374:2019 (animal feed). The focus was on reducing analysis time while maintaining sensitivity, accuracy, and precision.

Methodology and Instrumentation

A variety of commercial samples and certified reference materials (rice, juices, liver, mussels, feeds, kelp) were processed following CEN guidelines. Solid samples (0.2 g) and liquid samples (5 mL) were extracted in hot 0.1 M HNO3 with 3–6% H2O2 at 90 °C for 60 min to oxidize As(III) to As(V). Extracts were centrifuged, filtered (0.45 µm), and refrigerated prior to analysis.

• Chromatography: Agilent 1260 HPLC with PRP-X100 anion-exchange column (50 × 2.1 mm, 5 µm), isocratic mobile phase (40 mM ammonium carbonate, 3% methanol, pH 9) at 0.65 mL/min, 5 µL injection, run time <2 min.
• Mass Spectrometry: Agilent 8900 ICP-QQQ in single quadrupole mode, He collision gas to remove 40Ar35Cl+ interference on m/z 75, standard cones and spray chamber, RF power 1550 W.
• Quantification: External calibration (0.05–50 µg/L) with matrix-matched checks; standard addition applied to samples showing strong matrix effects (apple juice).

Key Results and Discussion

The method achieved baseline separation of As(V) from organic arsenic species and chloride interference in under two minutes. Detection limits were 1.99 µg/kg for solids and 0.08 µg/L for liquids; quantification limits were 6.64 µg/kg and 0.27 µg/L, respectively, well below EU regulatory thresholds. Calibration curves exhibited excellent linearity over the working range. Spike recoveries ranged from 90 to 110% for most matrices, with apple juice requiring standard addition due to matrix suppression. Precision (RSD) ranged from 0.3 to 9.4%, and accuracy against certified reference materials yielded recoveries of 81.8 to 110.7%. Retention time stability within sequences remained below 2% RSD.

Benefits and Practical Applications

This fast HPLC-ICP-MS approach offers high sample throughput and cost-effective routine monitoring of inorganic arsenic in diverse food and feed matrices. It meets stringent regulatory requirements, supports quality assurance in laboratories, and enhances consumer safety by enabling timely compliance testing.

Future Trends and Opportunities

Further development could focus on:

• Integration with single-quadrupole ICP-MS platforms for broader accessibility.
• Automation of sample preparation to increase throughput.
• Expansion to additional food and environmental matrices.
• Coupling with high-resolution mass spectrometry for comprehensive arsenic speciation.
• Miniaturized and field-deployable systems for on-site screening.

Conclusion

A rapid, robust HPLC-ICP-MS method for inorganic arsenic determination was successfully optimized and validated across multiple food and feed matrices. The approach delivers high sensitivity, excellent accuracy and precision, and complies with EU regulations and CEN standards, making it suitable for official control and routine laboratory use.

References

1. EFSA Scientific Opinion on arsenic in food, EFSA Journal, 2009, 7, 1351.
2. EU Regulation (EC) No. 1881/2006 and amendments.
3. EU Directive 2002/32/EC and amendments.
4. Jackson BP. Fast ion chromatography-ICP-QQQ for arsenic speciation. J Anal At Spectrom. 2015;30:1405–1407.
5. Gray PJ et al. A fast and fit-for-purpose arsenic speciation method for wine and rice. J Anal At Spectrom. 2017;32:1031–1034.
6. Tanabe CK et al. Fast Analysis of Arsenic Species in Infant Rice Cereals using LC-ICP-QQQ. Agilent publication 5991-9488EN.
7. Tanabe CK et al. Fast Analysis of Arsenic Species in Wines using LC-ICP-QQQ. Agilent publication 5991-8454EN.
8. EN16802:2016. Determination of inorganic arsenic in foodstuffs by anion-exchange HPLC-ICP-MS.
9. prEN17374:2019. Determination of inorganic arsenic in animal feed by anion-exchange HPLC-ICP-MS.
10. EU Regulation (EC) No. 333/2007 and amendments.