Fundamentals and new approaches to calibration in atomic spectrometry†
Despite efforts to develop calibration-free methods for atomic spectrometry, the most successful applications of quantitative instrumental techniques involve calibration. In this review paper, we discuss the principles and applications of both traditional and some recently described calibration methods as they are used in spectrochemical analysis. We particularly focus on the fundamentals, basic conditions and statistics of linear regression based on least-squares fitting, including the impact of normality and heteroscedasticity on accuracy. Advantages and limitations of the external standard calibration (EC), internal standardization (IS) and standard additions (SA) methods are critically discussed, as well as new calibration strategies such as interference standard (IFS), standard dilution analysis (SDA), multi-energy calibration (MEC), multi-isotope calibration (MICal), multispecies calibration (MSC) and multi-flow calibration (MFC).