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Chemometrics can be very useful for the classical field of UV–Vis determination of metals in aqueous solutions. A conventional approach consisting of using selective bands in a univariate mode is often not applicable to the real-world samples from e.g. hydrometallurgical processes, because of overlapping signals, light scattering on foreign particles, gas bubble formation, etc. And this is where chemometrics can do a good job. This paper overviews certain contributions to the field of multivariate data processing of UV–Vis spectra for seemingly simple case of metal detection in aqueous solutions. Special attention is given to applications in nuclear technology field.

A sensor array comprising potentiometric chemical sensors with solvent polymeric and chalcogenide glass membranes was developed and applied to the determination of copper, zinc, lead and cadmium ions’ activity at the nmol L−1 concentration levels. Sensors were able to detect copper down to the 0.2 nmol L−1, lead 0.4 nmol L−1, cadmium 0.06 nmol L−1 and zinc 30 nmol L−1 in individual buffer solutions. Collinearity of the sensors’ responses in the buffer and non buffer solutions confirms sensors’ sensitivity to these metals at the very low activity levels. Sensor array was capable to determine simultaneously these cations in the mixed buffer solutions at the background of 0.5 mol L−1 sodium chloride or artificial seawater with the accuracy of about 20%. Copper and zinc could be detected in the mixed solutions down to the concentration of 1 nmol L−1 and lead and cadmium at the concentration of 2 nmol L−1. Therefore, the sensor array is suitable for the detection of copper and zinc at the concentrations corresponding to the chronic seawater criteria, and lead and cadmium at the concentrations corresponding to the acute seawater criteria. The sensor array based on the potentiometric chemical sensors demonstrated a good promise as an instrument for rapid measurements of the ultra-low activities of copper, lead, zinc and cadmium in seawater.

A variety of novel sensing materials on the basis of phosphine oxides for solvent polymeric sensors have been developed and studied. It was found that phosphine oxide sensors exhibit good sensitivity to rare earth metal cations, such as La3+, Pr3+, Nd3+, Eu3+ and also to Y3+. Polymeric sensors can be comprised into electronic tongue sensor arrays that may allow detection of several rare-earth metal ions simultaneously in mixed solutions. Such sensor arrays are highly promising for environmental and industrial sensing, e.g., for analysis of spent nuclear fuel.

Application of chemometric methods to processing of the dynamic response of a flow-injection multiple-sensor system of the “electronic tongue” type is described. A through flow-injection multiple-sensor system of a new type is developed. The data processing is carried out using the method of projection to latent structures and the n-variate method of projection to latent structures (in processing of three-dimensional data). The results obtained in determining ions of lead and zinc in the case of their simultaneous presence in solution and comparative characteristics of various calibration models are presented.

Electronic tongues for liquid analysis, based on the organizational principles of biological sensory systems, developed rapidly during the last decade. A brief historical overview of the research and development in the field of electronic tongue systems is presented. Current achievements of scientific groups working in this field are outlined and critically reviewed. The performance of electronic tongues in quantitative analysis and in classification of multicomponent media is considered. The exciting possibility of establishing a correlation between the output from an electronic tongue and human sensory assessment of food flavour, thereby enabling quantification of taste and flavour, is described. Application areas of electronic tongue systems including foodstuffs, clinical, industrial, and environmental analysis are discussed in depth. Prospective research and development in the field of electronic tongues is discussed.

Development and analytical evaluation of a multisensor system based on the principles of “electronic tongue” for the determination of low contents of uranium(VI), uranium(IV), iron(II) and iron(III) in complex aqueous media have been carried out. A set of 29 different chemical sensors on the basis of all-solid-state crystalline and vitreous materials with enhanced electronic conductivity and redox and ionic cross-sensitivity have been incorporated into the sensor array. Multidimensional data have been processed by pattern recognition methods such as artificial neural networks and partial least squares. It has been demonstrated that Fe(II) and Fe(III) contents in the range from 10−7 to 10−4 mol L−1 of total iron concentration can be determined with the average precision of about 25%. U(VI) and U(IV) contents can been determined with the average precision of 10–40% depending on the concentration. The developed multisensor system can be applied in future for the analysis of mining and borehole waters as well other contaminated natural media, including on-site measurements.