Provided herein are methods and apparatus for collecting and preserving core samples from a reservoir. In some embodiments, a method includes obtaining core samples from a reservoir using a rock and fluid sampling tool and depositing the core samples in a vessel filled with a hydrogen-free fluid such that a portion of the hydrogen-free fluid is displaced by the core samples and the core samples are immersed in the hydrogen-free fluid. The method also includes transferring a gas into the vessel to occupy a space in the vessel and sealing the vessel via a cap on an end of the vessel. Methods of analyzing the core samples core samples collected from a reservoir and a rock and fluid sampling tool are also provided.