Explosives Analysis Using Thin-Layer Chromatography–Quantum Cascade Laser Spectroscopy
A new hyphenated technique using thin-layer chromatography (TLC) to separate analytes in mixtures, coupled with mid-infrared (MIR) laser spectroscopy for identification and quantification, is presented. The method, which provides a means for rapid screening of analytes that is practical, low-cost, f...
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| Format: | Article |
| Language: | English |
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MDPI AG
2025-04-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/30/8/1844 |
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| author | John R. Castro-Suarez Luis A. Pérez-Almodóvar Doris M. Laguer-Martínez José L. Ruiz-Caballero José A. Centeno-Ortiz Tamara Felix-Massa Leonardo C. Pacheco-Londoño Samuel P. Hernández-Rivera |
| author_facet | John R. Castro-Suarez Luis A. Pérez-Almodóvar Doris M. Laguer-Martínez José L. Ruiz-Caballero José A. Centeno-Ortiz Tamara Felix-Massa Leonardo C. Pacheco-Londoño Samuel P. Hernández-Rivera |
| author_sort | John R. Castro-Suarez |
| collection | DOAJ |
| description | A new hyphenated technique using thin-layer chromatography (TLC) to separate analytes in mixtures, coupled with mid-infrared (MIR) laser spectroscopy for identification and quantification, is presented. The method, which provides a means for rapid screening of analytes that is practical, low-cost, fast, robust, and reproducible, was tested using nitroaromatic and aliphatic nitro high explosives (HEs) as target analytes. HEs are anthropogenic contaminants containing an -NO<sub>2</sub> group. For validation of the new technique, a direct comparison of the 2,4,6-trinitrotoluene (TNT) spectrum, obtained by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy coupled with TLC, was carried out. The MIR laser spectroscopy-based method was evaluated by calculating the analytical figures of merit regarding the calibration curves’ linearity and the method’s sensitivity and precision. The TNT spectrum obtained by the MIR laser method showed two prominent and characteristic bands of the explosive at approximately 1350 cm<sup>−1</sup> and 1550 cm<sup>−1</sup> compared to the spectrum acquired by ATR-FTIR. The detection limit calculated for TNT was 84 ng, while the quantification limit was 252 ng. Multivariate analysis was used to evaluate the spectroscopic data to identify sources of variation and determine their relation. Partial least squares (PLS) regression analysis and PLS combined with discriminant analysis (PLS-DA) were used for quantification and classification. The new technique, TLC-QCL, is amenable to a smaller footprint with further developments in MIR laser technology, making it portable for fieldwork. |
| format | Article |
| id | doaj-art-63a3ddefdfb04f4794fc4474882a2691 |
| institution | OA Journals |
| issn | 1420-3049 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj-art-63a3ddefdfb04f4794fc4474882a26912025-08-20T02:18:15ZengMDPI AGMolecules1420-30492025-04-01308184410.3390/molecules30081844Explosives Analysis Using Thin-Layer Chromatography–Quantum Cascade Laser SpectroscopyJohn R. Castro-Suarez0Luis A. Pérez-Almodóvar1Doris M. Laguer-Martínez2José L. Ruiz-Caballero3José A. Centeno-Ortiz4Tamara Felix-Massa5Leonardo C. Pacheco-Londoño6Samuel P. Hernández-Rivera7Center for Chemical Sensors and Chemical Imaging and Surface Analysis Center, Department of Chemistry, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USACenter for Chemical Sensors and Chemical Imaging and Surface Analysis Center, Department of Chemistry, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USACenter for Chemical Sensors and Chemical Imaging and Surface Analysis Center, Department of Chemistry, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USACenter for Chemical Sensors and Chemical Imaging and Surface Analysis Center, Department of Chemistry, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USACenter for Chemical Sensors and Chemical Imaging and Surface Analysis Center, Department of Chemistry, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USACenter for Chemical Sensors and Chemical Imaging and Surface Analysis Center, Department of Chemistry, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USALife Science Research Center, Universidad Simón Bolívar, Barranquilla 080002, ColombiaCenter for Chemical Sensors and Chemical Imaging and Surface Analysis Center, Department of Chemistry, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USAA new hyphenated technique using thin-layer chromatography (TLC) to separate analytes in mixtures, coupled with mid-infrared (MIR) laser spectroscopy for identification and quantification, is presented. The method, which provides a means for rapid screening of analytes that is practical, low-cost, fast, robust, and reproducible, was tested using nitroaromatic and aliphatic nitro high explosives (HEs) as target analytes. HEs are anthropogenic contaminants containing an -NO<sub>2</sub> group. For validation of the new technique, a direct comparison of the 2,4,6-trinitrotoluene (TNT) spectrum, obtained by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy coupled with TLC, was carried out. The MIR laser spectroscopy-based method was evaluated by calculating the analytical figures of merit regarding the calibration curves’ linearity and the method’s sensitivity and precision. The TNT spectrum obtained by the MIR laser method showed two prominent and characteristic bands of the explosive at approximately 1350 cm<sup>−1</sup> and 1550 cm<sup>−1</sup> compared to the spectrum acquired by ATR-FTIR. The detection limit calculated for TNT was 84 ng, while the quantification limit was 252 ng. Multivariate analysis was used to evaluate the spectroscopic data to identify sources of variation and determine their relation. Partial least squares (PLS) regression analysis and PLS combined with discriminant analysis (PLS-DA) were used for quantification and classification. The new technique, TLC-QCL, is amenable to a smaller footprint with further developments in MIR laser technology, making it portable for fieldwork.https://www.mdpi.com/1420-3049/30/8/1844mid-infrared laser spectroscopythin-layer chromatography (TLC)trinitrotoluene (TNT)partial least squares regression (PLS)principal components analysis (PCA) |
| spellingShingle | John R. Castro-Suarez Luis A. Pérez-Almodóvar Doris M. Laguer-Martínez José L. Ruiz-Caballero José A. Centeno-Ortiz Tamara Felix-Massa Leonardo C. Pacheco-Londoño Samuel P. Hernández-Rivera Explosives Analysis Using Thin-Layer Chromatography–Quantum Cascade Laser Spectroscopy Molecules mid-infrared laser spectroscopy thin-layer chromatography (TLC) trinitrotoluene (TNT) partial least squares regression (PLS) principal components analysis (PCA) |
| title | Explosives Analysis Using Thin-Layer Chromatography–Quantum Cascade Laser Spectroscopy |
| title_full | Explosives Analysis Using Thin-Layer Chromatography–Quantum Cascade Laser Spectroscopy |
| title_fullStr | Explosives Analysis Using Thin-Layer Chromatography–Quantum Cascade Laser Spectroscopy |
| title_full_unstemmed | Explosives Analysis Using Thin-Layer Chromatography–Quantum Cascade Laser Spectroscopy |
| title_short | Explosives Analysis Using Thin-Layer Chromatography–Quantum Cascade Laser Spectroscopy |
| title_sort | explosives analysis using thin layer chromatography quantum cascade laser spectroscopy |
| topic | mid-infrared laser spectroscopy thin-layer chromatography (TLC) trinitrotoluene (TNT) partial least squares regression (PLS) principal components analysis (PCA) |
| url | https://www.mdpi.com/1420-3049/30/8/1844 |
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