Integrated calibration method (ICM) is one of the novel approaches in the field of analytical calibration. ICM enables several (e.g., six) estimates of an analytical result to be obtained in a single calibration procedure. These values respond differently and independently to errors caused by interference and non-linearity effects, thus making it possible to: (a) determine the accuracy of the analytical results, (b) detect interference effects in a sample, and (c) find an adequate way to eliminate the interference effect and to obtain results with improved accuracy. The presented work details the construction of a novel multicommuted flow manifold designed for realization of ICM, along with its operating rules. Accuracy and repeatability of the system were examined via spectrophotometric determination of chromium(III), and the obtained results are shown. Moreover, ICM used in this novel way was tested to verify the presence of, and to eliminate, systematic errors in the case of selenium determination, by using hydride generation-atomic fluorescence spectrometry (HG-AFS) in the presence of copper as an interferent. The procedure was also investigated for three real samples containing selenium, namely a diet supplement in the form of tablets, an energy drink and natural thermal water.

An original strategy to evaluate analytical procedures is proposed and applied to verify if the flow-based methods, generally favorable in terms of green chemistry, are competitive when their evaluation also relies on other criteria. To this end, eight methods for the determination of zinc in waters, including four flow-based ones, were compared and the Red–Green–Blue (RGB) model was exploited. This model takes into account several features related to the general quality of an analytical method, namely, its analytical efficiency, compliance with the green analytical chemistry, as well as practical and economic usefulness. Amongst the investigated methods, the best was the flow-based spectrofluorimetric one, and a negative example was that one involving a flow module, ICP ionization and MS detection, which was very good in analytical terms, but worse in relation to other aspects, which significantly limits its overall potential. Good assessments were also noted for non-flow electrochemical methods, which attract attention with a high degree of balance of features and, therefore, high versatility. The original attempt to confront several worldwide accepted analytical strategies, although to some extent subjective and with limitations, provides interesting information and indications, establishing a novel direction towards the development and evaluation of analytical methods.

A simple novel calibration approach called ‘the standard addition and indicative dilution method’ (SAIDM) is presented. It consists in addition of a standard solution to a sample and in successive dilution of this solution until the signal measured is equal to the signal produced by the undiluted sample. Due to the presence of the analyte in the sample environment, SAIDM can be effectively used when interference effects occur. It has been theoretically and experimentally proved that the method proposed is capable of overcoming strong interferences in flame atomic absorption spectrometry even in such cases where the standard addition method (SAM)—conventionally used for this purpose—fails. In addition, due to the possibility of avoiding the extrapolation process, it offers better precision than SAM. However, it has also been revealed that SAIDM cannot be considered as a versatile calibration approach because it leads to worse analytical results in terms of accuracy than SAM when the interference effect is of a multiplicative character.

A new calibration methodology based on the combination of integrated calibration method (ICM) and the H-point standard addition method (HPSAM) is presented. It allows the diagnosis and correction of errors caused in an analytical system by different kinds of interference effects. Six calibration solutions consisting of mixtures of sample, diluent, and one standard are prepared in accordance with the ICM principle to integrate the external calibration method with the standard addition method and thereby to detect and eliminate proportional interferences. Absorbance increments chosen according to the HPSAM principle are proposed to correct the errors caused by additive interferences. A set of as many as six apparent estimations of analyte concentration in a single calibration procedure is calculated for validating accuracy. As a consequence, doing calibration by the ICM-HPSAM method, it is possible to obtain the final analytical results with considerably improved accuracy. The determination of calcium in several different water samples (containing amounts between 4.9 and 127 mg L⁻¹) with Arsenazo III has been chosen as an example because it is biased if the errors are not diagnosed and corrected. The results are characterized by small (not higher than 8%) relative error (RE), and good precision (RSD values smaller than 6%).