Method of and apparatus for testing a sample

摘要

A method of detecting the presence of a particular substance in a given sample. According to the method, nuclear resonance is excited in a substance and response signals are detected from the substance using a probe. The probe is adjusted in dependence on the character of the sample. A method of detecting the presence of a sample which gives rise to interfering signals, not due to nuclear resonance, comprises exciting nuclear resonance in the sample, and detecting and processing the response signal from the sample in such a way as to at least partially filter out the interfering signals arising from the sample.