Preconcentration of thallium (III) by single drop micro extraction and its determination by electrothermal atomic absorption spectrometry in real samples and speciation of thallium (I) and (III)

Author:
, ,
Year
: 2011
Abstract: Abstract

Single drop micro extraction (SDME) in combination with electrothermal atomic absorption

spectrometry has been used to preconcentrate and determine thallium (III) ions followed by

speciation of thallium (I) and (III). 10.0 ml of aqueous sample of thallium containing 0.5 ml of

1% picric acid as a counter ion at pH= 6 was extracted into a 4 μl microdrop of nitrobenzene

containing dyciclohexano-18- crown-6 as complexing agent. After the extraction, the

microdrop was injected into a graphic furnace for thallium determination. Different parameters

affecting the extraction efficiency such as the type organic solvent, concentration of picric acid

and crown ether, volumes of organic and aqueous phases, pH, extraction time and temperature

were optimized. The effects of different interfering ions and methods of their eliminations were

conducted. Under the optimized conditions, thallium (III) was determined with detection limit

of 1.1 ng ml-1 and sensitivity of 0.3 ng ml-1. Relative standard deviation for five replicate

analysis of 10 ng ml-1 of thallium (III) was 4.2 percent. The calibration curve was linear in the

range of 1.1-32 ng ml-1 of thallium. The enrichment factor was calculated to be 80. Thallium (I)

and (III) speciation has been performed on the basis that thallium (III) forms a stable complex

with EDTA and would not enter into the micro drop and hence only thallium (I) can be

determined. The accuracy and validity of the method was evaluated using real samples of nail

and spiked tap water and also certified reference material.
Keyword(s): Keywords: thallium,single drop micro extraction,electrothermal atomic absorption

spectrometry,crown ether (Dicyclohexano–18– crown– 6),picric acid
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