This thesis describes a study of existing calibration methods and a comparison of them, with novel calibration and sample pre-treatment methods for flame atomic absorption spectrometry (FAAS) developed by the author. A comparison of commercially available curve fitting algorithms was carried out to show how concentration errors arise and vary, due to the use of different empirical models for the calibration curve. Novel online dilution manifolds were designed. Using flow injection and continuous flow techniques, different calibration procedures were developed to allow null methods of calibration to be used and to extend the calibration range. Methods of sample pre-treatment were developed, including online dissolution and species separation, using flow injection analysis techniques. Members of the atomic spectroscopy group of the Royal Society of Chemistry were surveyed to discover calibration practices used in commercial laboratories. Respondents were asked questions on sample type, treatment and presentation, and data reduction for calibration. During the research, several papers were published and lectures given on the topics described.