Rapid Wood Species Identification Using RADIAN™ ASAP Direct Mass Detector

Importance of the Topic

Accurate and rapid wood species identification is critical for enforcing forestry regulations, preventing illegal logging and timber substitution, and supporting sustainable supply chains. Conventional anatomical identification requires expert training and is often inadequate for processed wood products. Chemical fingerprinting by mass spectrometry offers objective, reproducible species discrimination; however, many MS workflows rely on laboratory infrastructure and chromatographic separation. The workflow presented here demonstrates a compact, chromatography-free mass spectrometric approach that can deliver near‑field, rapid screening suitable for regulatory, forensic, and industrial screening use.

Objectives and Study Overview

The study aimed to evaluate a rapid chemotyping workflow based on the RADIAN ASAP Direct Mass Detector combined with LiveID software to classify tropical hardwood species prone to substitution. Four commercially important heartwood species were analyzed: Swietenia macrophylla (mahogany), Cedrela odorata (cedar), Carapa guianensis (andiroba), and Hymenaea courbaril (jatoba). A total of 60 heartwood samples from multiple Amazonian sources provided realistic natural variability. The goals were to establish reproducible mass‑spectral fingerprints from solvent extracts, build chemometric classification models, and assess predictive performance for unknown samples.

Methodology

Sample preparation was intentionally simple to support rapid throughput and decentralized use: 3–5 mg of heartwood was extracted in methanol:water (3:1 v/v) and vortexed for 30 seconds. A pre‑cleaned glass capillary was dipped into the extract vial and used to introduce the sample into the RADIAN ASAP source.

Instrumental parameters used for method development included ASAP+ ionization, cone voltage 35 V, source temperature 120 °C, a temperature ramp from 100 °C to 600 °C at 100 °C/min, mass acquisition range m/z 200–1200, scan rate 2 Hz, and corona current 5 µA. Spectra were recorded across the programmed temperature gradient to identify the most informative thermal desorption window.

Used Instrumentation

The analytical platform comprised the RADIAN ASAP Direct Mass Detector for direct thermal desorption ionization without chromatographic separation, and LiveID software for automated spectral processing, dimensionality reduction, classification, cross‑validation and outlier detection. Routine consumables included autosampler vials and glass capillaries for sample introduction.

Data Processing and Chemometrics

Raw spectra (total 248 spectra) covering m/z 200–1200 were processed in LiveID. A two‑step chemometric pipeline was applied: principal component analysis (PCA) to reduce dimensionality and capture dominant variance, followed by linear discriminant analysis (LDA) as a supervised classifier to maximize inter‑class separation. Cross‑validation and outlier detection were implemented to quantify model robustness and avoid forced assignments for non‑represented samples.

Main Results and Discussion

RADIAN ASAP analysis of methanol/water extracts produced rich, information‑dense mass spectra with reproducible, species‑specific ion distributions across m/z 200–1200. Thermal profiling showed increasing higher‑m/z ion intensity up to ~400 °C with evidence of fragmentation or signal loss at higher temperatures; consequently 400 °C was selected as an optimal operating point for routine runs. Each species displayed distinct dominant ion regions reflecting differences in secondary metabolite composition; these metabolite‑driven fingerprints enabled clear visual and computational discrimination even where anatomical markers are lost.

The PCA‑LDA model demonstrated strong class separation and stability: cross‑validation yielded approximately 95% overall classification accuracy, with misclassifications concentrated in samples showing less distinctive spectral profiles. In a held‑out blind test simulating real‑world unknowns, all withheld samples were correctly identified with 100% confidence. The solvent‑extraction approach reduced source contamination relative to direct solid sampling and improved reproducibility. The fixed RADIAN ASAP source geometry and automated LiveID routines minimized method optimization needs and lowered the training barrier for non‑specialist operators.

Practical Benefits and Applications

• Very rapid screening: end‑to‑end analysis in minutes and under one minute per sample for routine screening.
• Minimal sample preparation: mg‑scale material and a short methanol:water extraction step.
• Chromatography‑free workflow: direct ASAP ionization eliminates the need for LC separation.
• Robust chemometric classification: PCA‑LDA with cross‑validation and outlier detection provided ~95% accuracy and 100% success on held‑out unknowns in this dataset.
• Compact and deployable: instrument platform and fixed source geometry support decentralized or near‑field deployment outside traditional HRMS labs.
• Accessible to non‑experts: automated software reduces the requirement for specialist spectral interpretation.
• Scalable: species libraries and classification models can be expanded to broaden application scope.

Future Trends and Potential Applications

Potential developments and extensions include expanding the reference spectral library to cover more species, geographic provenances, and processed wood products to increase applicability in customs and field enforcement. Integration with complementary methods — anatomical microscopy, DNA barcoding, or higher‑resolution MS for confirmatory testing — would create tiered workflows balancing speed and definitive identification. Advances in machine learning could improve classification robustness across larger libraries and noisy field data. Further miniaturization and ruggedization of direct MS platforms, as well as portable sample preparation kits, would enhance true near‑field deployment for customs checkpoints, logging operations, and supply‑chain verification.

Conclusion

The described RADIAN ASAP + LiveID workflow provides a fast, simple and robust route to wood chemotyping without chromatographic separation. Methanol:water extracts yield reproducible mass spectral fingerprints that, when modeled by PCA‑LDA, enable high‑confidence species discrimination suitable for screening and rapid decision support. The approach is particularly valuable for decentralized applications where rapid triage is needed before more resource‑intensive confirmatory analyses.

References

1. Cojocariu C., Baker R., Hanauer F., Wilson M., Langley G., Herniman J. Routine Chemicals and Materials Testing with RADIAN ASAP Direct Mass Detector. Waters Application Note, 2022.
2. Thays V. C.; Fioramonte M.; Pirolla R.; Gontijo A. B.; Nascimento C. S.; Higuchi N.; Jardim M. A. G.; Fasciotti M. Real‑Time Wood Chemotyping Using a Low‑Cost and Compact Mass Spectrometer. ACS Omega 2026, 11 (10), 16687–16699. DOI: 10.1021/acsomega.5c13161.