Determination of Elemental Composition of Animal Feed by ICP-OES According to EN 15621

Importance of the Topic

Accurate quantification of nutrients and trace elements in animal feed is essential for ensuring animal health, optimizing feed formulation and meeting regulatory standards. Monitoring both essential minerals and toxic contaminants helps feed manufacturers maintain product quality and safeguard the food chain.

Objectives and Study Overview

This study aimed to develop and validate a rapid, robust ICP-OES method on the Shimadzu ICPE-9820 for simultaneous determination of 22 elements in various commercial animal feeds. The method follows the European Standard EN15621 for sampling and analysis of animal feeding stuffs and addresses the needs for high throughput and wide concentration range analysis.

Methodology

Sample Preparation

• Weighed 1.0 g of dried feed into microwave vessels.
• Added 6 mL HNO₃ and 1 mL H₂O₂.
• Applied a three-step microwave digestion program: ramp to 200 °C (15 min at 1 800 W), hold at 200 °C (15 min), cooling (30 min).
• Transferred digests to 100 mL with ultrapure water.

Calibration

• Prepared two sets of external standards in 1% HNO₃ covering low (0.08–2 mg/L) and high (4–500 mg/L) concentration ranges.
• Used yttrium at 1 mg/L as internal standard.

Analytical Conditions

• Instrument: Shimadzu ICPE-9820 with mini plasma torch, concentric nebulizer and cyclonic spray chamber.
• RF power 1.20 kW; plasma gas 10.0 L/min; auxiliary/carrier gas 0.60 L/min.
• Dual view (axial for trace, radial for major elements); exposure time 15 s.
• Sensitivity set to wide range; rinse times adjusted for concentration.

Used Instrumentation

• ICP-OES: Shimadzu ICPE-9820
• Mini plasma torch
• Concentric nebulizer
• Cyclonic spray chamber
• Microwave digestion system

Main Results and Discussion

Calibration curves for all 22 elements exhibited excellent linearity (r > 0.9995). Method detection limits ranged from low µg/L levels to address trace contaminants. Analysis of eight feed samples (three dog, three cat, two rabbit) showed:

• Essential elements (Ca, P, K, Na, Mg, Fe, Zn, etc.) at levels consistent with feed formulation.
• Toxic elements (As, Cd, Pb, Se, etc.) were below detection or at minimal concentrations.

Precision studies demonstrated RSD < 3% for all analytes. Spike recoveries between 83% and 115% across different feed matrices confirmed method accuracy. Long-term stability tests showed intensity drift < 5% for yttrium over 4 hours and normalized recoveries within ±20% over 2.5 hours for all target elements.

Benefits and Practical Applications

The optimized ICP-OES method offers:

• Simultaneous multi-element detection from trace to major concentrations.
• High throughput compatible with routine feed quality control.
• Robust performance under complex sample matrices.
• Compliance with EN15621, facilitating regulatory acceptance.

Future Trends and Applications

Potential developments include automated sample handling, integration with chemometric data analysis, expansion to specialty feed matrices, and coupling with hyphenated techniques for speciation studies. Implementation of advanced software for spectral deconvolution may further improve accuracy and workflow efficiency.

Conclusion

A validated ICP-OES method on Shimadzu ICPE-9820 successfully quantified 22 elements in animal feed with high accuracy, precision and stability. The approach meets regulatory guidelines and supports feed manufacturers in delivering safe, well-balanced nutrition.

References

1. De Jonge LH, Jackson FS. The feed analysis laboratory: establishment and quality control. FAO Animal Production and Health Guidelines No. 15; 2013.
2. Da Costa SSL, Pereira ACL, Passos EA, Alves JD, Garcia CAB, Araujo RGO. Multivariate optimization of an analytical method for the analysis of dog and cat foods by ICP-OES. Talanta. 2013;108:157–164.
3. European Committee for Standardization. EN 15621:2017. Methods of sampling and analysis for animal feeding stuffs.