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Sample Handling in Infrared Spectroscopy — An Overview
Published in Patricia B. Coleman, Practical Sampling Techniques for INFRARED ANALYSIS, 2020
The most commonly used mulling agent is a clear white mineral oil sold under the trade name of Nujol™. The spectrum of Nujol™ (shown in Figure 11) exhibits C–H stretching frequencies in the region of 3000 to 2800 cm−1 and deformations at 1460 and 1375 cm−1. A weaker methylene rocking vibration occurs at 720 cm−1. These bands will all be observed in the spectrum of the mull and will overlap any corresponding carbon-hydrogen frequencies in the sample. In most cases, this is not a serious problem for identification since all of the other sample bands are free from interference by the Nujol™. If detailed information is needed at these wavelengths, a different mulling agent — one containing no C–H bonds — must be used. Fluorolube™ (a perfluorinated hydrocarbon) serves this purpose. Its spectrum is also shown in Figure 11, and it will be noted that it has no appreciable absorptions between 4000 and 1350 cm−1. If a full-range spectrum, completely free of any mulling agent bands, is required, it can be obtained by merging spectra of a Fluorolube™ mull (4000 to 1350 cm−1) and a Nujol™ mull (below 1350 cm−1) to give a “split-mull” spectrum. Care must be taken to match the thicknesses of the two mulls; this can be done with computer processing by normalizing on a band free of interference in both spectra. Figure 12 shows spectra of stearic acid run both as a Fluorolube™ mull and as a Nujol™ mull.
Application of a PLA/PBAT/Graphite sensor obtained by electrospinning on determination of 2,4,6-trichlorophenol
Published in Environmental Technology, 2023
Mario Cezar Pozza Junior, Andressa Giombelli Rosenberger, Franciele Fernanda da Silva, Douglas Cardoso Dragunski, Edvani Curti Muniz, Josiane Caetano
Sensor 3: A portion of 25 mg of graphite powder was heat treated under 500°C for 3 h using a tubular furnace (EDG10P-S) with N2 atmosphere (flow rate of 0.5 L min−1). Then, calcined graphite was mixed with mineral oil (wetting agent – Nujol®) in the proportion of 70:30 (m/m). The homogeneous paste formed was packed into the bottom of a hypodermic plastic syringe of 1 mL and manually pressed until the maximum compaction of the paste. To connect the graphite paste and the extremity, a silver filament was inserted inside the syringe.