A dataset of Raman spectra with quantitative labels of mixtures of nitrate, nitrite and sulphate

This article describes a dataset of Raman spectra acquired from aqueous solutions containing nitrate, nitrite, and sulphate ions at known concentration levels. The dataset includes 694 raw Raman spectra collected in the Stokes region from 400 to 3900 cm⁻¹, and each spectrum is associated with quantitative labels reporting the concentrations of nitrate, nitrite, and sulphate in mg/L. The data include single-analyte, binary-mixture, and ternary-mixture samples, covering a range of concentration values for the three target anions. The spectra were recorded using a micro-Raman system integrating an Olympus BXFM microscope, a 50× objective, and a Horiba iHR320 spectrometer equipped with a Horiba Syncerity CCD detector, with measurements performed under 532 nm excitation. The dataset is organized in spreadsheet files in which spectral intensity values are reported as a function of wavenumber, followed by the three quantitative concentration labels for each sample. This dataset can support the development, validation, and comparison of signal processing, chemometric, and machine learning approaches for Raman-based water analysis, including both qualitative recognition and quantitative estimation tasks in single- and multi-analyte conditions.