ONLINE DILUTION SYSTEM FOR EXTENDING THE CALIBRATION RANGE OF FLAME ATOMIC-ABSORPTION SPECTROMETRY

A flow injection manifold to extend the determination range of flame atomic absorption spectrometry is described. The sample plug is transported by the carrier to a variable volume (2-10 ml) mixing chamber. A plug of air displaces the diluted solution from the chamber, while facilitating mixing, and a constant signal is obtained for the absorbance-time relationship. The plateau height or integrated absorbance can be used as the analytical signal. The time needed to perform the measurements is only dependent on the volume of the chamber and the flow rate. The reliability of the manifold is checked by using concentrated solutions of copper and calcium. Repeatability of the integrated absorbance measurements is in the 1-4% range.