Peristaltic pumps-Fourier transforms: a coupling of interest in continuous flow flame atomic absorption spectrometry

The use of a simple continuous manifold, together with data treatment by means of Fourier transforms, permits the dynamic range of flame atomic absorption spectrometry to be extended. A peristaltic pump is used to move the analyte solution, the difference between the pumping flow rate and the nebulizer uptake rate being compensated by aspirating solvent through a T-piece. The time-variable absorbance profile which results from the action of the rollers is transformed into a frequency spectrum, the large signal caused by the periodical roller movement being used as the analytical signal. The effect of different experimental conditions on the signal is studied and the improvement in the signal/noise ratio lowers the determination limit. The dynamic range can be further extended, since the system also permits the measurement of solutions which are too concentrated to be measured by direct aspiration. Calibration is performed by means of a single standard solution.