Organic carbon (OC) and elemental carbon (EC) are major components of atmospheric PM. Typically OC and EC concentrations are measured using thermal optical methods from samples collected on quartz filters. However, these measurements are destructive and relatively expensive. In this work, we estimate TOR OC and EC using Fourier transform infrared (FT-IR) spectra from Teflon filters. Dillner and Takahama (2015a, b) showed the feasibility of accurate prediction developing calibration models for OC and EC using a subset of 2011 IMPROVE monitoring network samples. We evaluate the capability for the same calibration models to predict OC and EC in ambient samples collected in 2013, which includes the same six sites and 11 additional sites used in 2011. We also propose a statistical method by which we can compare the spectral similarity of new samples to those in the calibration set, and anticipate the magnitude of prediction errors prior to application of the calibration model.