Colorimetric sensors are essential in various chemical, biological, and environmental processes due to their ease of use, affordability, and environmental compatibility [1]. Detecting anions is crucial for health and safety, as certain anions can be hazardous to the environment. However, distinguishing between different anions can be challenging, highlighting the need for effective identification methods [2,3]. Anthraquinone-based sensors, especially those using hydroxyanthraquinone derivatives, show strong sensitivity and selectivity for detecting anions [4] In this study, we investigated the absorption properties of 1,8-dihydroxyanthraquinone, in different percentages of water/acetonitrile solutions (10:90, 60:40,70:30,10:90) in the presence of analytes such as carbonate, phosphate, cyanide, sulfite, and bicarbonate. Statistical methods such as principal component analysis (PCA) and hierarchical clustering analysis (HCA) were used to classify absorption data at various anion concentrations. The score plots generated from the analysis revealed distinct clusters with no overlap among them. The sensor could distinguish between different anions not only in individual solutions, but also in binary and ternary mixtures, as well as in real water samples. The optimal concentration range for accurate classification was 100-1000 µM, achieving an accuracy between 97-100%. Concentrations lower than 100 µM resulted in some overlap between classes. This concept proposes the development of multidimensional sensing platforms based on a single indicator capable of displaying various color and absorption responses upon the addition of different anion targets
