Page 188 - An Introduction to Analytical Atomic Spectrometry - L. Ebdon

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Table B.1 HPLC conditions.
Mobile phase 1 0.0001 M K SO (pH 10)
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2
Mobile phase 2 0.1 M K SO (pH 10)
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2
Column Strong ion exchange
Column size 300 mm x 4.6 mm i.d.
Column temperature 58°C

Column packing material Benson BA-X10
Mobile phase flow rate 1.2 ml min -1
Sample loop 200 µl

B.6.2.2 Hydride Generation Atomic Fluorescence

Hydride generator: PS Analytical continuous flow hydride generator.

Atomic fluorescence spectrometer: PS Analytical Excalibur atomic fluorescence spectrometer (AFS).

Reductant: A solution of 1% w/v sodium borohydride (NaBH ) should be freshly prepared in 0.1 M
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sodium hydroxide (NaOH), and placed in the 'reductant' reagent compartment of the PS Analytical
continuous flow hydride generator.

Acid blank: A solution of 3 M hydrochloric acid should be prepared and placed in the 'acid blank'
reagent compartment of the AFS.

The inlet line to the gas-liquid separator should be removed and connected to a plastic T-piece, which is
also connected to the outlet from the HPLC column. The T-piece should then be connected to the gas-
liquid separator with 7 cm of Teflon tubing.

When the hydride generation apparatus is then switched on, the NaBH and HCl solutions are pumped,
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via a peristaltic pump, to the T-piece where they are mixed with the column eluent before entering the
gas-liquid separator. The gases formed in the separator are swept, through a membrane drier, into the
AFS using an argon carrier flow. The AFS instrument should be connected to a chromatographic
integrator.

The instrumental conditions for the hydride generation atomic fluorescence instrument are given in
Table B.2. A diagram of the instrumental set-up is shown in Fig. B.1.

B.6.3 Procedure.
1 Prepare a 100 ng ml mixed standard solutions of arsenic by serial dilution of 1000 µg ml stock
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solutions of dimethylarsenic (DMA), monomethylarsenic (MMA), arsenic(III) and arsenic(V)