Automatic dilution system for use in flame atomic absorption spectrometry

Abstract

A fully computer-controlled manifold allowing the automatic dilution and measurement of solutions which are too concentrated to be measured by direct aspiration in FAAS is described. The sample solution is pumped by using a peristaltic pump equipped with two pump tubes of different diameters, the difference between the nebulizer uptake rate and the flow rate delivered by the pump being compensated for with solvent through a T-piece. Absorbance data are acquired by the computer during a time interval which is an exact multiple of the period of the rollers’ pulse. The absorbance is averaged and the pump turning speed automatically increased or decreased until an absorbance value centered within the linear response of the spectrometer is obtained. Calibration is carried out using a single standard solution.