Could anyone please suggest me a suitable protocol for determining SCFA ,amino acids,Bile acid, phenolics, sterols , indoles and heterocyclic amines in Human fecal samples using UHPLC-MS and GC-MS?I want to study the effect of different dietary habits on these metabolites.Can I use same method for different biofluids?For example,The method tested on urine can exactly be applied on fecal samples?