This article reports a new computerized approach to the simultaneous determination of low concentrations of toluene, heptane and 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4]) and 1-butyl-3-methylimidazolium methylsulfate ([bmim][MeSO4]) ionic liquids (ILs) in acetone using a correlation between their concentrations and UV-vis absorbance values. The essential information (absorbance data) from UV-vis spectrometer of quaternary mixtures in acetone was selected by a principal component analysis (PCA) and transferred into linear regressions (LRs) or neural network (NN) trained computer to estimate the concentrations. Such an integrated PCA/NN/UV-vis spectroscopy system is capable of estimating the concentrations of chemicals in acetone, based on the created models and patterns, without any previous phenomenological knowledge. The mean difference between the estimated concentrations using the PCA/NN/UV-vis and the real concentrations of toluene, heptane, [emim][EtSO4], and [bmim][MeSO4] is less than 2.5%. The PCA/NN/UV-vis is one of the first reliable approaches that can be used in the ILs mixtures field to determine the concentration of two ILs and hydrocarbons in quaternary mixtures while at the same time having simple applications. The short time required by PCA/NN/UV-vis to measure all four chemicals makes it especially useful in processes where long sample preparation times are required.