Fluorescent sensing arrays for cations and anions

Array-based sensing methods can be used to distinguish sets of similar analytes, by using a number of non-specific or cross-reactive probes. Following subsequent statistical analysis, patterns or components can be isolated that can be used to unambiguously identify the specific analyte(s) present. Over the past two decades, various arrays for the identification of cations and anions have been reported. These often employ fluorescence methods, owing to good sensitivity and a versatile, easy to read output. The past few years have seen an increase in the number of such studies reported in the literature. This critical review will summarise this recent work, and identify the criteria required for a successful array system. In particular, it will focus on the different types of molecular structures that can be used, the breadth of ions that can be distinguished in a single array, the sensitivity and dynamic range to which they can be identified, and how successfully these aims have been met.