Fabrication of Atom Trapping, Vapor Generating and Hydride Generating Devices for Flame Atomic Spectrometer and Determination of Cadmium, Mercury and Arsenic with Higher Sensitivity

Document Type : Research Note


Department of Clean Technologies and Environment, Chemistry and Chemical Engineering Research Center of Iran, Tehran, I.R. IRAN


Presence of toxic elements like cadmium, mercury and arsenic at ppb range in environmental resources may increase the risk to human health. Determination of these elements at such ranges needs a relative sensitive technique with enough low detection limit. Atomic absorption spectrometric methods provide simple and low cost techniques for such measurements. However, their detection limits in simple instrumentations lies in ppm ranges. At present work, sensitivity enhancement in determination of cadmium, mercury and arsenic using atom trapping and vapor generation techniques in atomic absorption spectrometry is investigated. In first step, an atom trapping device using a slotted quartz tube is fabricated. The device is then employed to analyzing those elements in aqueous solutions and a 2-3 enhancement is achieved. The detection limit of cadmium is improved from 20 ppb in simple FAAS to 5 ppb in atom trapping AAS. At second step, sensitivity enhancement for analyzing mercury and arsenic is investigated. A cold vapor generator is fabricated to analyzing mercury in aqueous solutions. The detection limit achieved by this method is 0.1 ppb which is 3 orders of magnitude better than flame one. The third step is determination of arsenic by hydride generation method, because cold vapor technique cannot be applied to this element. So, a hydride generator is fabricated with a slight modification of previously made cold vapor generator. A detection limit of 1 ppb is achieved by this method. In summary, such techniques provide simpler and cheaper analyzing methods for determination of volatile elements in aqueous samples. One may use specific digestion procedure for analyzing samples rather than aqueous one by such methods.


Main Subjects

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