ELEMENTAL ANALYSIS OF DTPA-EXTRACTED MICRONUTRIENTS IN SOILS USING AN AGILENT 4210 MP-AES

Significance of the Topic

Soil micronutrient levels directly affect plant health and crop yields. Accurate determination of trace metals such as Cu, Fe, Mn and Zn is essential for soil fertility management and environmental monitoring. The DTPA extraction method is widely accepted for assessing plant available micronutrients. Coupling this extraction with a robust analytical technique ensures reliable data for agricultural decision making.

Objectives and Overview of the Study

This study aims to evaluate the performance of the Agilent 4210 Microwave Plasma Atomic Emission Spectrometer for measuring DTPA extracted soil micronutrients. Key goals include assessing calibration linearity, detection limits, spike recoveries and long term stability under conditions typical of soil extracts.

Methodology and Instrumentation

A standard DTPA soil extraction procedure was applied to dried and ground soil samples using diethylenetriaminepentaacetic acid buffered at pH 7.3. Extracts were analyzed on the Agilent 4210 MP AES equipped with a microwave plasma source operating on nitrogen gas supplied by a Dewar or a nitrogen generator. MP Expert software and a plug and play torch enabled streamlined workflow and minimal training. Main analytical parameters included wavelengths 324.754 nm for Cu, 259.940 nm for Fe, 257.610 nm for Mn and 213.857 nm for Zn.

Main Results and Discussion

Calibration curves for all elements demonstrated excellent linearity over the tested ranges (Cu and Zn 0.5–5 µg/mL, Mn 5–50 µg/mL, Fe 10–100 µg/mL) with correlation coefficients from 0.999 to 1.000. Method detection limits at a 10 g sample weight were low (0.03–0.06 mg/kg), supporting trace level analysis. Spike recovery studies at relevant soil concentrations yielded recoveries between 90 and 92 percent. Signal stability was maintained with less than 2 percent RSD over a three hour run, indicating reliable performance for extended sample batches.

Advantages and Practical Applications

The Agilent 4210 MP AES offers cost savings through use of nitrogen plasma gas and eliminates flammable gases, improving laboratory safety and reducing supply costs. Its high tolerance to matrix effects and capacity for multi element analysis make it suitable for routine soil testing in agronomy, environmental monitoring and quality control laboratories.

Future Trends and Potential Applications

Advances in plasma spectrometry and software automation will further enhance throughput and data quality. Integration with robotic sample preparation and coupling with geospatial analysis can create comprehensive soil health management systems. Potential extensions include analysis of other trace elements and adaptation to field deployable instrumentation.

Conclusion

The Agilent 4210 MP AES in combination with DTPA extraction provides a robust, accurate and cost effective solution for soil micronutrient analysis. High sensitivity, excellent precision and user friendly operation support its adoption in diverse agricultural and environmental laboratories.

Reference

• Agilent Technologies. Elemental analysis of DTPA extracted micronutrients in soils using an Agilent 4210 MP AES. Application Note 5991-7787EN, May 2017.