Given the extensive characterisation of the methods, the concept followed is that samples should be adapted to a consistent and well-characterised analytical platform by conscientious preparation. This approach deviates from the practice of adapting specific methods to specific sample types, which multiplies the number of analytical methods which require characterisation in the form of MetID. Instead, by minimising the number of methods maintained within a laboratory, it becomes easier to deploy them more consistently (e.g., in the form of dedicating an instrument to a specific method type) and allows investment made in any one method in the form of characterising the elution of analytes (MetID) to be amortised across more sample analyses and types. Sample preparation SOPs for blood product and urine analysis by each method described above (RPC, HILIC, and Lipid RPC) are presented in the appendices and recommended as points of departure for other biofluids.