This invention relates to methods and devices for NMR spectroscopy analyzing sealed containers e.g., food and beverage containers and other containers, and particularly according to specific embodiments sealed containers made of a conducting but generally nonferromagnetic metal or other conducting material. As discussed in above referenced applications, many current strategies for contaminant detection require a container to be violated, a process that can destroy the container or product and is impractical in large scale applications. The present invention overcomes these and other problems by providing methods and devices for the detection of contaminants and/or contraband in metal or conducting containers by NMR spectroscopy.