In order to ensure the feasibility of complex liquid spectroscopy analysis, to analyze the accuracy gain of modeling by multi-wavelength, and to determine the appropriate distribution of concentration to obtain the high quality and universal quantitative analysis model, the precision of the detection of composition concentration by spectral analysis is illustrated through a error analysis which takes into account the following three contributions: spectral instrument noise, multi-wavelength modeling and the distribution of composition concentration. By concentration resolution analysis, the concentration resolution can be achieved when the spectrometer noise is available, but also the theoretical basis is provided to select a suitable spectrometer to meet the resolution requirement of quantitative analysis. Over-sampling technique indicates that the precision improvement by modeling with multi-wavelength can obtain higher concentration detection sensitivity. The sparse-dense-ratio and Euclidean distance of both measured and non-measured components provide the theoretic guidance for choosing the suitable concentration distribution which improves the model's quality and reduces the prediction error of the sample set.