Speciation Neutron Activation Analysis (SNAA):

Chief limitation of NAA is that it cannot be used for speciation studies. However, its scope can be further extended by chemical separation of specie(s) prior to irradiation and then determining the elemental content. This is necessary because the toxicity of an element depends significantly on its physicochemical form. There is a rising interest in studying speciation by NAA because of its low detection limits. It involves two steps; first the separation of species from the sample followed by the detection of element by NAA.  A variety of methods involving liquid chromatography, ion exchange, reversed phase chromatography,  hydride generation, liquid-liquid extraction, solid phase extraction, coprecipitation etc. have been developed for the separation of various inorganic, organic and organometallic species. The main advantage of SNAA includes simultaneous speciation of elements such as Cl, Br and I that are rather hard to be determined through other techniques. A SNAA method has been developed in combination with HPLC for the determination of low levels of five arsenic species, As (III), As (V), monomethylarsonic acid (MMA),  or dimethylarsenic acid (DMA) and arsenobetaine (AsB) in natural water samples.