1. A method for developing models to predict physical and chemical properties of a petroleum fluid, comprising: (a) providing a fluorescence spectrum for each of a set of calibration samples of petroleum fluids, wherein each sample of petroleum fluid has known values of one or more preselected properties of interest, wherein the fluorescence spectrum for each of a set of calibration samples have one or more spectrum parameters; (b) developing a first stage model for each of the preselected properties of interest to predict such preselected properties of interest, wherein each first stage model being based on the fluorescence spectrum for each of the calibration samples, wherein the first stage model for each of the preselected properties of interest correlates to the same preselected property of interest for a calibration sample of the set of calibration samples with the spectrum of such calibration sample; (c) obtaining first-stage prediction properties from the first-stage models based upon first-stage variables obtained from the fluorescence spectrum and spectrum derived parameters for each of the set of calibration samples of petroleum fluids; (d) developing a second-stage model for at least one of the preselected properties of interest to predict such preselected property of interest, wherein each second-stage model is based on the first-stage prediction properties and the first-stage variable for such preselected property of interest obtained from the first-stage model for such preselected property of interest; and (e) obtaining second-stage prediction properties from the second-stage models based upon second-stage variables obtained from the first-stage predicted properties and the first-stage variables.