Analysis of Microalgae Biomass by TOC and TG

Significance of the Topic

Microalgae biomass analysis plays an essential role in advancing sustainable biofuel production and understanding cellular carbon dynamics. Accurate determination of organic and inorganic carbon content informs process optimization, productivity assessment, and environmental impact evaluations in industrial and research applications.

Objectives and Study Overview

This study aimed to establish a rapid and accurate approach for quantifying total carbon (TC) and moisture content in three microalgae species (Emiliania huxleyi, Tisochrysis lutea, and Chlorella vulgaris). By combining total organic carbon (TOC) solid sample analysis with thermogravimetric (TG) measurements, the method enables direct analysis of wet pellets and calculation of dry-cell carbon content.

Methodology and Instrumentation

TOC analysis was performed using a Shimadzu TOC-LCPH coupled with an SSM-5000A solid sample combustion unit under 500 mL/min oxygen at 900 °C, calibrated with 40 % glucose carbon powder. Moisture content was determined using a DTG-60 simultaneous thermogravimetric/differential thermal analyzer, heating samples from ambient temperature to 800 °C at 20 °C/min in air. Microalgae suspensions were centrifuged, washed, and pellet weights (20–100 mg) recorded for analysis.

Main Results and Discussion

• TC versus pellet weight exhibited excellent linearity across all species, indicating uniform carbon recovery and reliable sampling.
• TGA profiles revealed moisture contents of 69.9–71.6 %, with primary water loss below 200 °C and minor weight changes at higher temperatures due to cellular component transformations.
• Combining TC data with moisture corrections produced a linear relationship between dry cell weight and total carbon, validating the method for dry biomass assessment.

Benefits and Practical Applications

The proposed procedure significantly reduces analysis time compared to traditional dry weight methods by eliminating lengthy drying steps. It enhances sampling precision, allows direct analysis of wet pellets, and offers robust monitoring of microalgae growth in biofuel research, QA/QC operations, and industrial analytics.

Future Trends and Potential Applications

• Integration into real-time monitoring systems for continuous carbon content assessment during cultivation.
• Extension to diverse microalgae strains and evaluation of additional biochemical targets such as lipids and pigments.
• Application in environmental biotechnology and wastewater treatment for rapid biomass and carbon flux characterization.

Conclusion

The integration of TOC solid sample analysis with thermogravimetric measurements provides a fast, accurate, and user-friendly strategy for total carbon quantification in microalgae. This approach overcomes limitations of conventional dry weight assays and supports precise, high-throughput evaluation of biomass productivity.

References

Shimadzu Review, Vol. 75, No. 1/2, pp. 33–39 (2018)