Nondestructive instrumental technique INAA

Photo-acoustic spectroscopy has been used for ultratrace levels of Hg in air and snow (de Mora etal. 1993). X-ray fluorescence is nondestructive, rapid, requires minimal sample preparation, and was, for example, used successfully to determine the maximal level of mercury in maternal hair to assess fetal exposure (Toribora et al. 1982). However, the procedure is less sensitive compared to AAS and INAA if no pre-concentration is used. Electrochemical methods have been replaced as detectors in chromatography by other instrumental techniques because of poorer detection limits. High-performance liquid chromatography (HPLC) with reductive amperometric electrochemical reduction, however, was shown to be capable of speciating Hg(II), methyl- ethyl- and phenylmercury, with detection limits <2pgL (Evans and McKee 1987). 

Making an Activation-Analysis Measurement. The most prominent technique in nuclear analytical chemistry is Instrumental neutron activation (INAA), in which thermal neutrons from a nuclear reactor are used to irradiate the sample and the induced radionuclides are measured nondestructively with a germanium gamma-ray spectrometer. Sensitivity may be enhanced by chemically separating the elements of interest before radionuclide assay. 

Several analytical methods have been deployed for the determination of uranium in ores. Among the older methods that were used are radiometric methods that were already used over 50 years ago for ore sorting (Mal tsev 1960), titrimetric methods in which the nraninm content in the ore was determined with ferrous ion-phosphoric acid reduction (Hitchen and Zechanowitsch 1980), colorimetric methods where complexes of nraninm are formed with standard arsenazo 111 (Onishi and Sekine 1972), exotic siderophores (Renshaw et al. 2003) reagents and instrumental neutron activation analysis (INAA) based on measurement of Np in the ore (Chaudhry et al. 1978) in addition to nnmerons other approaches. Many modem techniques are now employed for destrnctive and nondestructive determination of uranium in ores. 

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