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| Sulphuric Acid on the WebTM | Technology Manual | DKL Engineering, Inc. |
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Knowledge for
the Sulphuric Acid Industry Introduction
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There
are few methods to analyse arsenic, but the fastest and most reliable system is
determination by Atomic Absorption as volatile hydride. The sample is treated with
potassium persulphate and sulphuric acid in order to oxidize the arsenic to As(V), because
in this oxidation state, the volatile hydride of the element produces a more time-constant
signal. The reduced form of arsenic, As(III),
produces a stronger but more random signal.
Pour 50 ml of arsenic
free water in a 100 ml flask. Add about 1 to 2 grams of acid to be tested (exactly
weighed). Add 1 gram of potassium persulphate pure reagent and 1 ml of hydrochloric acid.
Heat on the water-bath for about 90 minutes to ensure all As(III) is oxidized to AS(V). Allow the sample to cool for about an hour and
make up to the mark. The solution is ready to be analysed in Atomic Absorption by hydride
system evolution. If possible use a
double beam spectrometer equipped with an automatic VHE system, like the Perkin Elmer MHS
20 or FIA one. Put 1 ml of the sample into
the VHE system, add the proper solutions, as recommended by the instrument instruction
manual and read the absorption peak (or directly concentration) at 193.7 nm. Determine,
the arsenic concentration against previously defined calibration curves. None
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Copyright© 2005,
2006, 2007, 2008 DKL
Engineering, Inc., All Rights Reserved |
