A lots of GC-MS literatures are using rentention time index for peak identification, anyone can share experience how to prepare rentention time standard mixture? We are using methoxyamine hydrochloride in pyridine and MSTFA as the derivatizing agent.
My second question is, we bought 1 ml MSTFA from Thermo Scientific (1 box has 10 ampules of 1 ml MSTFA). After run some samples, there will be left about an amount of MSTFA in the vial. Is that okay to use the left amount of the MSTFA for the next analysis (we keep the rest from the open ampule in fridge).
Thank you for the feedback!