Multi-Element Analysis of Trace Metals in Animal Feed using ICP-OES

Importance of Multi-Element Analysis in Animal Feed

Animal feeds must meet strict safety and quality standards due to potential contamination by trace metals that can affect animal health and product quality. Rapid, routine screening of both major and trace elements supports raw material evaluation, in-process monitoring, and final product QA/QC to detect contamination sources early and ensure compliance with regulatory limits.

Objectives and Study Overview

This work presents a streamlined method for simultaneous determination of 23 elements in animal feed using an Agilent 5110 VDV ICP-OES equipped with the Advanced Valve System (AVS 7). Method development considered AOAC 985.01 recommendations for eight key elements and extended to additional targets, aiming to deliver high throughput, low cost analysis suitable for QA/QC laboratories.

Methodology and Instrumentation

An Agilent 5110 Vertical Dual View ICP-OES with optional AVS 7 valve was used. Key features include:

• Integrated torch alignment and mass flow controllers for stable plasma operation
• AVS 7 switching valve and positive displacement pump to minimize uptake times and rinse delays
• Yttrium (371.029 nm) and bismuth (223.061 nm) as internal standards to correct ionic and atomic interferences
• Mixed use of radial view for major elements and axial view for trace elements

Sample preparation employed microwave digestion of certified reference materials (0.5 g in 50 mL) using HNO₃ and HCl to minimize volatile losses. Calibration was performed with linear standards across optimized concentration ranges, and background correction employed Fitted Background Correction (FBC) and Fast Automated Curve Fitting Technique (FACT) to handle complex spectral structures.

Key Results and Discussion

Limit of detection (MDL) and quantitation (LOQ) ranged from sub-0.1 mg/kg for trace elements to single-digit mg/kg for major constituents, ensuring suitability for regulatory thresholds. Calibration curves for all 23 elements showed correlation coefficients >0.999. Method accuracy was validated via:

• Spike recovery in corn bran CRM within ±10%
• Analysis of four feed CRMs with recoveries of certified elements within ±10% after moisture correction
• Long-term stability over 6 hours (330+ samples) with QC recoveries within ±10% and RSD <3%

A productivity comparison between the VDV and Synchronous VDV (SVDV) configurations demonstrated that SVDV reduced analysis time by 25%, lowered argon consumption by 25%, and increased sample throughput by approximately 34% under identical operating conditions.

Benefits and Practical Applications

This method offers:

• High-throughput multi-element screening with rapid startup and minimal operator variability
• Robust interference correction via automated background and FACT modeling
• Cost-efficient operation with moderate argon consumption and short analysis times (64 s per sample)
• Scalable productivity by upgrading to SVDV without altering chemistry or calibration

Future Trends and Potential Applications

Advances in ICP-OES hardware and software are expected to enhance sensitivity and further reduce consumable costs. Coupling VDV/SVDV instruments with automated sample handling and data analytics could enable real-time monitoring in feed mills. Emerging guidelines may extend to additional contaminants, necessitating flexible multi-element platforms.

Conclusion

The presented Agilent 5110 ICP-OES method provides a fast, reliable, and economical approach to comprehensive trace metal analysis in animal feeds. Its accuracy, precision, and scalability support routine QA/QC applications, and the option to adopt SVDV mode offers further gains in throughput and efficiency.

Reference

1. Agilent Technologies Inc. "Benefits of a Vertically Oriented Torch—Fast, Accurate Results, Even for Your Toughest Samples." Publication 5991-4854EN, 2016.
2. Agilent Technologies Inc. "Reduce Costs and Boost Productivity with the Advanced Valve System (AVS) 6 or 7 Port Switching Valve System." Publication 5991-6863EN, 2016.
3. AOAC International. AOAC 985.01 "Metals and Other Metals in Plants and Pet Foods." 2005.
4. Agilent Technologies Inc. "Fitted Background Correction (FBC) – Fast, Accurate and Fully Automated Background Correction." Publication 5991-4836EN, 2016.
5. Agilent Technologies Inc. "Real-Time Spectral Correction of Complex Samples Using FACT Spectral Deconvolution Software." Publication 5991-4837EN, 2016.