Dear community,

we are currently collecting - amongst other things - blood and stool samples of patients in an observational trial; one of our aims is the analysis of bacterial metabolites in blood and gut.

Stool samples are collected by the patients outside the clinic, so we use collection tubes pre-filled with a stabilizing buffer; patients collect one defined spoonful of sample and mix it with the buffer instantly.

Our first analyses of the samples showed that our MRI spectroscopy works well for those samples; however, as we do not collect the samples ourselves, we do not have the exact weight of the stool sample added to the buffer. Unfortunately, the tubes we use are not exactly equal in weight (filled weight with 9 ml buffer: 16,5 g - 16,9 g); as the sample weight is an estimated 1 g, this variability is rather big.

Do you have an idea on how we could normalize our samples? The buffer consists mainly of ethanol, however it is bought pre-mixed, and its exact formulation is proprietary.

Ideally, 1 spoonful of fecal sample (approx. 1 g) is added to 9 ml of buffer.

Best

Ronald