Sample stacking with in‐column silylation for less volatile polar compounds using GC‐MS

This paper presents sample stacking with in-column silylation (SIS) for quantitative analysis of less volatile polar compounds using gas chromatography-mass spectrometry (GC-MS). This was achieved by the combination of sandwiched in-column silylation and multiple injections (up to 100 times or 100 μL in total). N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) was used as a silylating reagent. For the SIS technique, samples were introduced multiple N times (N = 2~100) into a capillary column in between BSTFA injections. The quantitative characteristic of SIS technique was studied using bisphenol A (BPA) as a model compound. The sandwiched in-column silylation for the less volatile polar compounds effectively replaced polar hydrogen with trimethylsilyl group to reduce sample adsorption and band broadening. Meanwhile, multiple injections at the SIS technique contributed to increase the sensitivity quantitatively. The capability and limitation of this analytical approach were further investigated with various types of compounds such as hydroxyls, carboxylic acids, and amine.