Determination of Moisture in Plant Tissue

Significance of the Topic

The accurate determination of moisture in plant tissue is critical for ensuring product quality in agricultural and botanical industries. Moisture content influences drying, curing, and storage processes, with both excessive moisture and over-drying leading to deterioration, mold growth, and compromised analytical results. Reliable moisture data also serve as essential corrections for compositional analyses of plant constituents such as carbon and nitrogen.

Objectives and Study Overview

This application note demonstrates the use of LECO's TGM800 and TGA801 macro thermogravimetric analyzers for loss-on-drying measurements in various plant matrices. The primary aim is to establish a robust, high-throughput method capable of delivering precise moisture content values for routine quality control and research applications.

Methodology

• Sample Preparation: Uniform plant tissue samples (leaf material) with masses between 1.0 and 5.0 g are loaded into appropriate crucibles.
• Thermogravimetric Conditions: Temperature ramp from 25 °C to 80 °C at 6 °C/min, followed by a 120-minute isothermal hold; analysis duration up to 240 minutes.
• Atmosphere and Ventilation: Measurements conducted in air with flow rates of 4.0 LPM for the TGM800 and 10.0 LPM for the TGA801; constancy criteria set at a 9-minute window and 0.0005 g mass stability.
• Moisture Calculation: Moisture content determined by the ratio of mass loss to initial sample mass, following preset method calculations.
• Optional Acceleration: A higher ramp rate (20 °C/min) can be employed to shorten analysis time without compromising accuracy.

Used Instrumentation

• TGM800 Macro Thermogravimetric Analyzer (up to 16 samples; aluminum foil crucibles, small and large sizes).
• TGA801 Macro Thermogravimetric Analyzer (up to 19 samples; ceramic crucibles).
• Accessories: Carousels, double-sided spoons for sample handling.

Key Results and Discussion

• Reproducible moisture values were obtained for reference materials such as alfalfa (≈6.4%), tobacco (≈2.8%), and orchard leaves (≈4.2%) across both instruments.
• Standard deviations remained below 0.05% moisture, highlighting the precision of the loss-on-drying approach.
• Comparable performance between small and large crucible formats and between TGM800 and TGA801 indicates method robustness and flexibility for different sample throughputs.

Benefits and Practical Applications of the Method

• High-throughput analysis with parallel processing of up to 19 samples reduces laboratory bottlenecks.
• Accurate moisture determination supports quality assurance during drying and curing, preventing product spoilage.
• Data integration for moisture correction enhances the reliability of downstream compositional analyses.

Future Trends and Potential Applications

• Integration of rapid heating profiles and automation to further decrease analysis times.
• Coupling thermogravimetric data with spectroscopic or mass spectrometric detectors for comprehensive plant tissue characterization.
• Implementation of remote monitoring and IoT-enabled data logging for real-time process control in industrial drying operations.
• Expansion of validated methods to additional botanical matrices, including seeds and roots, for broader agricultural applications.

Conclusion

The TGM800 and TGA801 thermogravimetric analyzers provide a reliable, precise, and high-throughput solution for moisture determination in plant tissues. By maintaining tight control over temperature, airflow, and end-point criteria, the method ensures reproducible results critical for quality control and research. Ongoing developments in automation and analytical coupling promise to extend the utility of this approach within the life sciences and industrial sectors.