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Identification of Microplastics and Nanoplastics and Associated Analytical Challenges
Published in Hyunjung Kim, Microplastics, 2023
The potassium bromide method is regarded as being predominantly difficult in that the attainment of a suitably transparent disc requires a very specific set of conditions to be met. For this reason, relatively large pieces of plastic are best analyzed using a reflectance technique, such as ATR. ATR only requires that the sample is in sufficiently close proximity to a small crystal. This crystal is typically composed of either germanium (Ge), diamond or zinc selenide (ZnSe). Once in contact with the crystal, an evanescent wave propagates 0.5–5 μm past the crystal surface and into the surface of the sample. Thus, the main requirement with ATR is that the sample is sufficiently in contact with this crystal to allow penetration of infrared radiation into the sample. This can be achieved by making use of a clamp to press the sample against the crystal (Figure 8.8).
Corrosion Testing: Practice
Published in Ole Øystein Knudsen, Amy Forsgren, Corrosion Control Through Organic Coatings, 2017
Ole Øystein Knudsen, Amy Forsgren
The most important FTIR techniques include Attenuated total reflectance (ATR), in which a sample is placed in close contact with the ATR crystal. ATR is excellent on smooth surfaces that do not degrade during the test.Diffuse internal reflectance (DRIFT). DRIFT uses potassium bromide pellets for sample preparation and therefore has certain limitations in use with hygroscopic materials.Photoacoustic spectroscopy (PAS). In PAS, the sample surface absorbs radiation, heats up, and gives rise to thermal waves. These cause pressure variations in the surrounding gas, which are transmitted to a microphone— hence the acoustic signal [55].
Qualitative Fourier Transform Infrared Spectroscopic Analysis of Polyether-Based Polymer Electrolytes
Published in Chin Hua Chia, Chin Han Chan, Sabu Thomas, Functional Polymeric Composites, 2017
Siti Rozana Bt. Abdul Karim, Chin Han Chan
There are different types of infrared sampling technique intended to be used for different types of samples and one of these techniques is attenuated total reflectance (ATR). This technique is used to analyze solids, liquids, semisolids, and thin films.90 ATR needs very minimal sample preparation and it is a non-destructive sampling technique. In ATR, an accessory is mounted in the sample compartment of FTIR. At the center of the ATR base assembly is a crystal (e.g., diamond, germanium, and zinc selenide (ZnSe)) which is used to reflect the IR beam from the source to the sample and then to the detector. Figure 8.5 shows the schematic diagram of an ATR base assembly.
Exploring the phytoremediation potential of water hyacinth by FTIR Spectroscopy and ICP-OES for treatment of heavy metal contaminated water
Published in International Journal of Phytoremediation, 2020
Huiling Peng, Yamin Wang, Tuck Lee Tan, Zhong Chen
Some plants have the ability to extract or remove inactive metals and metal pollutants from contaminated soil and water (Tangahu et al. 2011). The accumulation processes include heavy metal mobilization, root uptake, metal transporters, cellular compartmentation and sequestration and so on (Komal et al. 2015). In our work, FTIR was performed as a powerful analytical tool to identifies the types of chemical bonds present in a sample by measuring the absorption of infrared radiation that was rarely used for the analysis of water hyacinth tissue after heavy metal phytoremediation. To our knowledge, none of the previous studies have reported the use of FTIR in attenuated total reflection (ATR) mode for analysis. Our work could provide a novel experimental method to explore heavy metal uptake and translocation in plants. Conventional FTIR method uses the KBr technique which comes with the disadvantage of having tedious sample preparation, involving hydraulic press of dried sample with KBr to form a pellet for analysis. KBr is hygroscopic and improper handling can affect the quality of the results. The ATR technique on the other hand simply requires the sample to be clamped against a highly refractive crystal for measurement and is able to overcome the disadvantage of the KBr method, allowing for a more accurate and reproducible results.
Towards chemical imaging: Fourier transform infrared mapping on organo-mineral materials
Published in European Journal of Environmental and Civil Engineering, 2018
T. Bonnal, G. Foray, E. Prud’homme, S. Tadier
With reflective modes, accessories can be used leading to different sampling techniques (Khoshhesab, 2012). In Attenuated Total Reflectance (ATR) (Ebbert et al., 2014; Monasterio et al., 2015), a crystal is placed on the sample surface and a pressure is applied to obtain a good contact between the crystal and the surface. The incident infrared light passes through the crystal and reflects directly on the material (Figure 2(b)). This technique has widely been used because it requires little or no sample preparation. Moreover, the crystal focuses the incident infrared light leading to a better spatial resolution. In a mapping utilisation, to maintain a good signal to noise ratio, isolated contacts have to be successively made on the surface of the sample requiring a large acquisition time. With a diameter of 300 μm on the tip, the successive contacts can damage the surface in case of low hardness of the material (Figure 3(a) and (b)). Moreover, when two components have different mechanical properties, the successive contact may lead to both cross contamination and matter accumulation at their interface (arrow on Figure 3(c)). This mode leads to cartography with a 6.25 μm² up to 1.56 μm² resolution using a zoom (multiplicity of infrared acquisition on a location).
Proposing a new infrared index quantifying the aging extent of SBS-modified asphalt
Published in Road Materials and Pavement Design, 2018
Chuanqi Yan, Weidong Huang, Feipeng Xiao, Lianfang Wang, Yanwei Li
The penetration depth of the infrared beam into a sample at a given frequency (wavenumber) in the ATR is a function of this frequency and the penetration depth significantly affects the peak intensity (Harrick & Beckmann, 1968). For most ATR equipment, the depth is approximately 0.5∼2 µm, which is barely bigger than the average size of SBS particles within SBSMA. The SBS particle size within SBSMA is governed by numerous factors including SBS dosage, sulphur dosage, storage time/temperature, etc. (de Carcer et al., 2014; Dong et al., 2014; Fu et al., 2007; Larsen et al., 2009). According to fluoroscope observation, sulphur-stabilised SBSMA usually possesses an average particle size of 1∼10 µm (those without sulphur have even bigger particles) and the size shrinks greatly when SBSMA is heated. Related studies (de Carcer et al., 2014) have recorded this particle size reduction along with aging and corresponding fluorescence micrographs are cited in Figures 2 and 3.