Coupling of thin layer chromatography (TLC) to quantum cascade laser spectroscopy (QCLS) for qualitative and quantitative field analyses of explosives and other pollutants

Abstract

The invention provides the use of instrumentation and methods for the rapid separation, detection, and identification of chemical compounds by coupling a well-established chromatographic separation science technique, TLC, with mid-infrared (MIR) QCLS for the analysis of explosives, pollutants, and other threat chemicals. The stationary phases were silica gel adhered to metallic aluminum supports. The mobile phases consisted of organic solvents and their mixes. The position and spot diameter of the TNT samples on the plate containing the adsorbent silica film were measured and compared before and after the chromatographic runs. The MIR vibrational identification of TNT was performed through reflectance measurements using a widely tunable three-diode source. The symmetric stretching vibration of the nitro group [νs(NO2)] centered at approximately 1350 cm−1 and the asymmetric stretching vibration of the nitro group [νas(NO2)] at approximately 1530 cm−1 were clearly observed. TLC-QCLS allows for the rapid and reproducible separation, identification, and quantification of explosives in the field in a short amount of time.

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