Determination of Moisture and Ash in Plant Tissue (TGA801)

Importance of the Topic

Determining moisture and ash content in plant tissue is essential for maintaining product quality, ensuring safe storage, and supporting accurate downstream analyses. Moisture control prevents microbial growth and over-drying, while ash measurement evaluates cleaning efficiency and informs compositional corrections for elements such as carbon, nitrogen, and sulfur.

Study Objectives and Overview

This application note describes a thermogravimetric analysis (TGA) method using the LECO TGA801 to quantify moisture and ash in plant materials. The protocol covers method parameters, sample preparation, calculation formulas, and typical performance data for reference materials.

Methodology

The analytical approach relies on TGA to record mass changes as a function of temperature under controlled atmospheres. Separate temperature ramps and hold times are applied for moisture removal (25 – 80 °C, 6 °C/min, 120 min in air) and ash determination (80 – 500 °C, 6 °C/min, 60 min in oxygen). Key calculation formulas include:

• % Moisture = (Initial Mass – Post-dry Mass) ÷ Initial Mass × 100
• % Ash = (Residual Mass ÷ Initial Mass) × 100
• % Ash Dry Basis = Ash ÷ (1 – Moisture Fraction)

Used Instrumentation

• LECO TGA801 Macro Thermogravimetric Analyzer
• Ceramic crucibles (density 3.0 g/cm³)
• Double-sided sample spoon

Results and Discussion

Typical data for certified reference materials show consistent performance with low standard deviations: 6.46 % moisture and 9.98 % ash (Alfalfa), 2.92 % moisture and 9.43 % ash (Tobacco), and 4.17 % moisture and 5.66 % ash (Orchard Leaves). Repeatability (s ≤ 0.03 %) confirms the method’s reliability. Temperature control and atmosphere selection effectively separate moisture loss from combustion processes.

Benefits and Practical Applications

• Quality control in drying operations to prevent spoilage or over-processing
• Assessment of cleaning and separation steps in biomass and agricultural products
• Accurate moisture correction for elemental analysis and compositional studies

Future Trends and Potential Applications

Emerging developments include coupling TGA with evolved gas analysis (EGA) for detailed volatile profiling, automating sample handling for higher throughput, and integrating remote monitoring for real-time process control in industrial drying systems.

Conclusion

The LECO TGA801 method provides a robust, reproducible approach for simultaneous moisture and ash determination in plant tissue. Its straightforward workflow and reliable performance make it suitable for lab and production environments where precise moisture control and compositional assessment are critical.

Reference

• LECO Corporation. Determination of Moisture and Ash in Plant Tissue. Application Note, Form No. 203-821-607, Rev. 2, 2020.