Analysis of algae using Pyrolysis and THM

Significance of the topic

Understanding the composition of complex biological materials such as algae and characterizing multicomponent polymer formulations are critical in both environmental and industrial contexts. Analytical pyrolysis coupled with GC/MS enables rapid profiling of biofuel precursors from algae, while GPC-IR hyphenation provides detailed molecular information on polymer blends used in specialty inks and coatings. Together, these approaches support bioenergy research, quality control and the development of advanced materials.

Objectives and study overview

The application note presents two complementary analytical strategies:

• Assessment of dried algae samples by analytical pyrolysis and thermally assisted hydrolysis/methylation (THM) to profile biopolymers and fatty acid content.
• Separation and identification of individual polymer and additive components in a silver-ink paste using gel permeation chromatography with infrared detection (GPC-IR).

Methodology

Samples of dried algae were subjected either to direct pyrolysis at elevated temperature or to THM in the presence of tetramethylammonium hydroxide (TMAH). In direct pyrolysis large biopolymers are thermally cracked into smaller volatile fragments, whereas THM converts fatty acids into methyl esters with minimal backbone degradation. In the polymer study, a GPC system equipped with an infrared detector collected IR spectra of size-fractionated components, enabling component-specific identification via characteristic absorption bands.

Used Instrumentation

• Pyroprobe 5250 Autosampler interfaced to GC/MS
• Quartz spacer rods and quartz wool containment
• Pyrolysis conditions: 600°C for 15 seconds
• THM conditions: 400°C for 20 seconds, with 2 μl of 25% TMAH in methanol, 5-minute dwell
• GC/MS parameters: Helium carrier, 50:1 split, 25 m × 0.25 mm 5% phenyl column; oven program 40°C (2 min) ↑ 10°C/min to 300°C (5 min); mass range 35–550 amu
• GPC-IR: DiscovIR-LC system capturing full FT-IR spectra of eluting fractions

Main results and discussion

Pyrolysis of algae at 600°C yielded complex pyrograms containing aromatic, nitrile and aliphatic fragments alongside intact desorbed compounds. Fatty acid moieties appeared as a series of normal alkanes and alkenes. In contrast, THM at 400°C produced simplified chromatograms dominated by fatty acid methyl esters, facilitating quantification of lipid content. In the polymer analysis three major components were resolved:

• Polymer A: a high-molecular-weight aliphatic polyester resin with broad MW distribution and strong adhesion properties.
• Polymer B: a medium-MW aliphatic polyurethane exhibiting elastomeric flexibility, cross-linkable via tri-functional isocyanates.
• Component C: a latent cross-linker (Desmodur LS-2800) stable at ambient conditions but activated thermally to generate tri-isocyanate species.
• Additive C: a ketooxime-blocked HDI trimer that deblocks above 150°C to cross-link with polyurethane segments, forming a robust 3D network capable of retaining conductive silver particles.

Benefits and practical applications

These analytical workflows enable rapid screening of algae strains for biofuel potential and detailed lipid profiling without extensive sample preparation. GPC-IR analysis equips formulators with insight into polymer architectures and additive functionality, supporting quality control, intellectual property evaluation and competitive differentiation of specialty inks and coatings.

Future trends and potential applications

• Integration of hyphenated techniques such as GC-IR, LC-IR and GPC-MS for real-time monitoring of bioprocesses and polymer curing.
• Expansion of spectral libraries and chemometric approaches to increase confidence in component identification and quantitation.
• Application to emerging feedstocks, biodegradable polymers and multilayer packaging systems for sustainability assessment.

Conclusion

The combination of analytical pyrolysis/THM-GC/MS and GPC-IR extends the analytical toolbox for both biofuel research and polymer formulation. By tuning thermal conversion conditions and leveraging spectral detection, complex mixtures can be deconvoluted into actionable molecular insights, accelerating development in energy, materials and manufacturing sectors.

Reference

• Challinor, J. M., The development and application of thermally assisted hydrolysis and methylation reactions, Journal of Analytical and Applied Pyrolysis, 61 (2001) 3–34.