A highly stable, temperature-controlled permanent magnet ensures easy maintenance-free operation without the need for liquid cryogens. The unit occupies a small fraction of the space of a conventional NMR spectrometer, and it does not require specialized knowledge or training for operation. NMR data is generated in the industry-standard JCAMP-DX format for compatibility with standard NMR data analysis packages. The unit's fluid capillary is contained within a cartridge, so it can be replaced easily by the user in case it becomes blocked or contaminated.