Automatic sample handling and calibration methods for analysis by flame atomic absorption spectrometry using discontinuous flow analysis

Abstract

The method of discontinuous flow analysis (DFA) is presented as a rapid, automated method of sample handling and analysis in flame atomic absorption spectrometry (FAAS). Three DFA arrangements for combined DFA-FAAS are described. The first provides automatic calibration in approximately 30 s using a single solution, the second provides rapid automated standard additions and the third provides an automated version of the sample bracketing procedure. The last two methods allow for concurrent calibration and determination of samples in a single operation lasting around 30 s. This continual re-calibration minimizes the effects of instrument drift and ensures accurate and precise measurement. The DFA-FAAS combination provides a great deal of information that could be used to advantage, for quality assurance purposes. However, this extra information gathering does not require additional labour on the part of the operator because only one or two standard solutions need to be employed to construct complete analytical calibration curves. In contrast to other automated methods of sample handling, the DFA technique uses high-precision cam-driven piston pumps and a valve arrangement to manipulate flowing streams containing reagents, diluents, standards and samples in a controlled and rapid fashion.