Non-destructive detections

Radiation Personnel Accident. Radiation exposure in accidents of personnel in nuclear facilities and non-destructive detection have been evaluated with ESR dosimetry. For example, the amputated medium fibre bone of a worker in Peru, who tried to solve the problem by directly touching the source of 60Co unit for a few seconds, was measured four years later.The dose was measured by 6.4 + 0.5 Gy, while 20 + 3 Gy was obtained from fluorescence in situ hybridization method. The result would suggest diagenic decay of the signal due to the metabolism of bone.96 Thus, ESR gives the retrospective dose for radiation accidents. 

Ion detection in FT-ICR instruments is unique (Fig. 18). It is a non-destructive detection method, which means multiple measurements can be performed on the same ions. 

Nuclear magnetic resonance spectroscopy (NMR) is one of the most powerful analytical methods for identification and structure elucidation of organic compounds. Since NMR spectra are recorded in solution, no phase transfer like in MS is necessary when coupled with LC techniques. Additionally, NMR is a non-destructive detection technique, allowing the analyte to be transferred for characterization using additional methods. As of today, LC—NMR coupling was used in a wide range of applications [65,66,67,68,69,70,71],... 

Illuminated alternately with UV and visible light, the porphyrinic dithienylethene underwent a reversible photoisomerization reaction (Scheme 1). Meanwhile, the fluorescence intensity of the porphyrin macrocycles could be regulated by alternate irradiation with UV (313nm) and visible light (longer than 480 nm). Moreover, the selective excitation band of the fluorophore was beyond the spectral band which could induce the photoisomerization reaction. Therefore, the authors asserted that this compound could act as a system for reversible data processing using fluorescence as the non-destructive detection method. 

Thomas, P., Kannan, A., Dagowekar, V.H., and Ramamurthy, M.S. 1995. Non-destructive detection of seed weevil-infested mango fruits by X-ray imaging. Postharvest Biol. Technol. 5, 161-165. 

The reflective wavelength of cholesteric liquid crystals varies according to temperature. Such an effect has been made useful in thermography. It has been applied in the diagnosis of cancers by displaying the skin temperature distribution. It has also been applied to test faults in integrated circuits. The applications also include thermometers and temperature warning indicators and non-destructive detection. 

Lacey R. J., Direct non-destructive detection and identification of contraband using Raman microscopy, lEE Conf. Publ., 408, 138-141, 1995. 

While the relative mass resolution of ca 10 of the SCSl-MS technique can compete very well with standard QMF and TOF mass spectrometers, the mass accuracy of the SCSI-MS technique will probably never be able to challenge that of FT-ICR mass spectrometry nevertheless, this shortcoming does not mean that the new technique is irrelevant. On the contrary, the SCSI-MS technique encompasses the advantages of high spatial and tanporal resolution from QMF and TOF together with the ability to perform non-destructive detection from FT-ICR. 

Other non-destructive detection methods use iodine vapors or iodine-potassium iodide reagents (Mylius s reaction). Yellow, orange, or brown zones will appear on the layer. The zones will have to be marked, because the iodine will eventually evaporate. The sensitivity of the iodine test can be greatly increased by the use of layers containing rhodamine 6G. Most of the steroids are recovered unchanged after exposure for 30 min with iodine vapor, except for estrogen and Vitamin D. 

Stannic chloride (Rgt. No. 236) is now only rarely used for detection. If no success is obtained with fluorescence layers, iodine vapour (Rgt. No. 141) or rhodamine B reagent (No. 220) can be used for non-destructive detection. 

Non-destructive detection, so important for preparative TLC, can be achieved by using known fluorescent adsorbents the fluorescence is quenched by UV-absorbing substances. The regular use of such adsorbents is recommended. Convenient fluorescent properties can be imparted to the layer after TLC, e. g., by spraying with morin [32] (No. 169), 2, 7 -dibromo- or 2, 7 -dichlorofluorescein [43, 127] (No. 63), various dyes [193] or an optical bleach like UVITEX [131] (Nos. 258,259). Visualisation with iodine is very useful [1, 12, 122, 125, 218] (No. 141), yielding unstable coloured addition products. The zones of hpophilic substances in preparative TLC can be rendered visible also by means of a fine spray of water [10, 69]. 

Detection is carried out with cerium (IV) stdphate (Bgt. No. 37). It cannot be used with layers impregnated with silver nitrate, nor with alumina layers. Iodine vapour or solution (Rgt. No. 143) or para-formaldehyde-phosphoric acid (Rgt. No. 194) can be used also and 2,4-dinitrophenylhydrazine (Rgt. No. 82) with alkaloids containing a keto group. The cerium (IV) sulphate reagent is recommended as a universal detection agent zl -unsaturated compounds yield a colour reaction even in the cold. Iodine vapour permits non-destructive detection of the sterol alkaloids, so that they may be subsequently isolated unchanged. 

Q. Chen, C. Zhang, J. Zhao and Q. Ouyang, Recent Advances in Emerging Imaging Techniques for non-Destructive Detection of Food Quality and Safety, TrAC, Trends Anal. Chem., 2013, 52, 261. 

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