Hydrocarbons concentrations are determined in drilling cuttings samples by generating a model for predicting hydrocarbons concentrations. Methods include dividing multiple samples removed from drilling fluid into two one set analyzed using a retort, and another set analyzed using a handheld NIR spectrometer to obtain NIR diffuse reflectance data. PLS analysis is used to correlate the retort data with the diffuse reflectance data to generate a calibration model. The model is validated with samples having unknown hydrocarbons concentration. The model is used to predict the hydrocarbons concentration for samples removed from drilling fluid taken from the rig site using the spectrometer to obtain diffuse reflectance data. During measurements, each sample contains 0.1 to 10 wt % moisture and each sample is in a clear container pressed against the spectrometer window such that the IR source from the handheld device can pass to the drilled solids sample within the clear container without opening the clear container.