ABSTRACT
Metal ion speciation involves the use of various spectroscopic techniques, such as ultraviolet-visible, flame atomic absorption, atomic emission, hydride generation, graphite furnace, inductively coupled plasma (ICP), and x-ray. In spite of the development of advanced chromatographic and electrophoresis methods for metal ion speciation, spectroscopic methods continue to be utilized for metal ion speciation due to certain advantages. The spectroscopic method of arsenic determination is based on the reaction of ammonium molybdate with arsenate in acidic medium to form an arsenatecontaining molybdenum heteropolyacid that can be reduced to molybdenum blue with stannous chloride, hydrazine, or ascorbic acid. Mass spectrometry has been coupled to ICP, resulting in a delicate research tool intended for the well-trained scientist only, in a more robust and well-established analytical technique for trace and ultra-trace determination, with a few thousand instruments in use worldwide. Hollow cathode lamps for different elements are used as the radiation sources.
