A RNAA method has been developed for the simultaneous determination of Rb and Cs in geological samples. The method is based on precipitation with sodium tetraphenylborate followed by NaI(Tl) gamma spectrometry. Three mica dust particulate samples and two USGS standard rocks, BCR-1 and W-1 were analyzed. Dipicrylamine (DPA) and 2-thenoyl-trifluoroacetone (TTA) in nitrobenzene were also used for solvent extraction. The precipitation method is better than solvent extraction.
Instrumental Neutron Activation Analysis (INAA) has been employed for the multielemental determination of an IAEA intercomparison standard Hay Powder, V-10 and some edible plant leaves consumed in India. The samples were irradiated with thermal neutrons at a flux 1012 n·cm–2·s–1 in a reactor for 5 minutes, 1, 2, 5, 10 and 15 hours and counted by high resolution -ray spectrometry. Nearly 18 elements have been determined. Good agreement is observed for most of the elements in several NBS standards and the proposed CRM V-10. Some edible vegetable plant leaves have also been analyzed.
Short-term reactor irradiation followed by successive counting over long periods has been used for the nondestructive determination of more the 20 elements in geological and biological samples. The samples, along with USGS standards and NBS SRMs, were irradiated for 5 m, 10 m, 15 m, 1 h, 2.5 h, and 10 h, followed by counting on a Ge/Li/ gamma-ray spectrometer. The technique has been employed for the determination of several major, minor, and trace constituents in geological, biological and environmental samples.
Radiochemical NAA methods have been developed for the simultaneous determination of Fe and Zn in biological samples. The method involves reactor irradiation, dissolution in 3M HCl and solvent extraction followed by counting on a scintillation gamma-ray spectrometer. Iron was separated with aqueous cupferron and extracted into chloroform while Zn was extracted with 2-thenoyl trifluoroacetone (TTA) into methyl isobutyl ketone (MIBK). Reaction conditions such as pH and the effect of solvents and various ions were studied using tracer activities. The methods have been employed for trace level determination of Fe and Zn in NBS, SRMs, Bowen's Kale, IAEA CRMs and other plant leaves.