File Name : ghb-edc am figure s1.pdf

Caption : figure s1. 	typical full scan mass spectra of ghb-edc<sub></sub>a / ghb-edc<sub></sub>b (a) and d<sub></sub>6-ghb-edc<sub></sub>a / d<sub></sub>6-ghb-edc<sub></sub>b (b) derivatives, and accurate mass measurements data of the four mh<sup></sup>+ ions.

File Name : ghb-edc am figure s2.pdf

Caption : figure s2. 	derivatization yields of the ghb-edc derivatives at different temperature and time reaction conditions.

File Name : ghb-edc am figure s3.pdf

Caption : figure s3. 	stability of ghb-edc derivatives kept at different temperatures and times before instrumental injection.

File Name : ghb-edc am figure s4.pdf

Caption : figure s4. mh+<sup></sup> collision-induced product ion spectra (merging of collision energies at 10, 25, 50 ev) of ghb-edc, bhb-edc, and bhisob-edc for both type a and type b derivatives.