Peristaltic pumps and Fourier transforms in flame atomic absorption spectrometry: use of standard additions method and on-line dilution procedures

The use of periodically pulsed peristaltic pumps to introduce samples in fl ame atomic absorption spectrometry allows the signal obtained during the sa mpling time to be treated with Fourier transform. In this work two applicat ions of this methodology are presented: the standard additions method and t he on-line dilution of the sample. In both cases two peristaltic pumps are used. For the standard additions method, the process is carried out in two experiments using three standards. The developed procedure has been applied to copper, calcium and chromium determination in the presence of several i nterferents. The RSD and accuracy were lower than +/- 2% and 5%, respective ly. The second application permits high on-line dilutions of sample. In thi s case, two periodically pulsed peristaltic pumps rotate in opposite ways. This method and the use of 0.5 mm id tubes and a sampling time of 13 s, per mits copper concentrations as high as 2000 mug ml(-1) to be determined.