title: Colorimetric sensing of anions in water using ratiometric indicator-displacement assay.
abstract: The analysis of anions in water presents a difficult challenge due to their low charge-to-radius ratio, and the ability to discriminate among similar anions often remains problematic. The use of a 3×6 ratiometric indicator-displacement assay (RIDA) array for the colorimetric detection and identification of ten anions in water is reported. The sensor array consists of different combinations of colorimetric indicators and metal cations. The colorimetric indicators chelate with metal cations, forming the color changes. Upon the addition of anions, anions compete with the indicator ligands according to solubility product constants (K(sp)). The indicator-metal chelate compound changes color back dramatically when the competition of anions wins. The color changes of the RIDA array were used as a digital representation of the array response and analyzed with standard statistical methods, including principal component analysis and hierarchical clustering analysis. No confusion or errors in classification by hierarchical clustering analysis were observed in 44 trials. The limit of detection was calculated approximately, and most limits of detections of anions are well below μM level using our RIDA array. The pH effect, temperature influence, interfering anions were also investigated, and the RIDA array shows the feasibility of real sample testing.
authors.affiliation: Laboratory of Instrumentation and Analytical Chemistry, Key Laboratory of Separation Science for Analytical Chemistry of CAS, Dalian Institute of Chemical Physics, CAS, Dalian, Liaoning, PR China. fengl@dicp.ac.cn
authors.forename: Liang
authors.initials: L
authors.lastname: Feng
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Xiao
authors.initials: X
authors.lastname: Li
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Zheng
authors.initials: Z
authors.lastname: Shen
authors.forename: Yafeng
authors.initials: Y
authors.lastname: Guan
mesh_terms: D000838:Anions / Q000032:analysis*; D003124:Colorimetry / Q000379:methods*; D057166:High-Throughput Screening Assays; D057230:Limit of Detection; D014867:Water / Q000737:chemistry*
chemical_list: D000838:Anions; D014867:Water