Determination of macro and micronutrients in plants using the Agilent 4200 MP AES

Significance of the Topic

Adequate plant nutrition underpins crop health and productivity by ensuring essential macro and micronutrient supply. Rapid and accurate determination of elements such as N, P, K, Ca, Mg and trace elements B, Cl, Fe, Mn, and Zn in plant tissues enables timely agronomic interventions. Traditional techniques include FAAS and ICP OES but operational drawbacks like flammable gases and limited detection for certain elements persist.

Study Objectives and Overview

This application evaluates the performance of the Agilent 4200 MP AES based on nitrogen plasma for simultaneous quantification of twelve nutrients in plant leaves. The study compares sensitivity, linear dynamic range, detection limits and accuracy against established methods, using certified reference materials and real corn samples.

Instrumentation Used

• Agilent 4200 MP AES fitted with 4107 nitrogen generator
• Double pass cyclonic spray chamber and OneNeb nebulizer
• Solvaflex pump tubing and Easy-fit torch for sample introduction
• MP Expert software for auto-optimization and background correction

Methodology and Instrumentation

Plant samples and apple leaf CRM were acid digested using microwave assistance with HNO3 and H2O2 in TFM-PTFE vessels under controlled temperature and pressure ramps. Calibration standards for macronutrients were prepared from 5 to 75 mgL-1 and for micronutrients from 0.05 to 4 mgL-1 in 1 percent HNO3. The MP AES operating parameters included pump speed 15 rpm, read time 15 s, and three replicates per sample. Emission wavelengths and nebulizer gas flows were optimized for each element.

Results and Discussion

Calibration curves exhibited excellent linearity across 0 to 75 mgL-1 for macronutrients and 0 to 4 mgL-1 for micronutrients. Method detection limits ranged from low µgkg-1 levels for elements like Mg and Zn to under 6 µgkg-1 for phosphorus. Recoveries for CRM analysis were within 90 to 110 percent, confirming accuracy. Corn leaf analysis revealed macroelements in the gkg-1 range and microelements in mgkg-1. The nitrogen plasma technology eliminated flammable gases, reduced costs, and provided wider linear dynamic range than FAAS, obviating multiple dilutions and streamlining workflow.

Benefits and Practical Applications

• Enhanced safety by using nitrogen plasma instead of flammable gases
• Lower operating costs and simpler gas supply requirements
• Improved sensitivity for challenging elements such as P, Si and B
• Broader dynamic ranges reduce dilution steps and contamination risk
• High throughput with automated optimization and background correction

Future Trends and Potential Applications

Integration of MP AES into automated sample handling and laboratory information management systems will enhance throughput in agricultural and environmental labs. Advances in plasma generation and detector technology may further lower detection limits and expand the element set. Coupling with speciation tools and direct solid sampling approaches could broaden applications beyond plant analysis, including soils and fertilizers.

Conclusion

The Agilent 4200 MP AES with nitrogen plasma demonstrates robust analytical performance for macro and micronutrient determination in plant tissues. Its safety, cost advantages, sensitivity and wide dynamic range make it a compelling alternative to traditional FAAS and ICP OES methods in agricultural laboratories.

References

1. DECREE 4954/2004 January 14th 2004 Regulation of Law 6894 Brasil Ministerio da Agricultura Pecuaria e Desenvolvimento
2. AGRIBOOK Agrichem do Brasil Ltda 2010
3. Nogueira A R A Manual de Laboratorio Solo Agua Nutricion Vegetal Nutricion Animal y Alimentos Sao Carlos 2005 p 334