Page 189 - An Introduction to Analytical Atomic Spectrometry - L. Ebdon

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Table B.2 Instrumental conditions for hydride generation atomic fluorescence spectrometry.
Carrier gas flow rate 250 ml min -1
Membrane drier purge gas 500 ml min -1

Reductant 1% NaBH in 0.1 M NaOH
4
Acid blank 3 HCl
M
Lamp Boosted arsenic hallow -cathode lamp
Lamp primary current 27 mA
Lamp boost current 35 mA

Figure B.1

2 Inject the standard into the sample loop of the HPLC instrument and observe the output of the
atomic fluorescence instrument on the chromatographic integrator. On elution of the first arsenic
species, switch the mobile phase from 0.0001 M K SO4 to 0.1 M K SO4 (step gradient elution).
2
2
3 Switch back to the 0.0001 M K SO mobile phase and allow the column to re-equilibrate for 15 min
4
2
after the chromatographic run (each run lasts about 25 min).
4 Insert a 10 m long Teflon reaction coil between the HPLC column and the gas-liquid separator with
a Teflon T-piece between the reaction coil and the HPLC column, as shown in Fig. B.1.

5 Pump a 0.7% solution of -cysteine in 0.05 M HCl at a rate of 0.2 ml min into the T-piece.
-1
L
6 Repeat steps 2 and 3 above.

B.6.4 Discussion

1 What were the main advantages of using AFS as the method of detection for this analysis?