As six
authentic compounds, viz. 1-hydroxy-2-naphthoic acid, salicylic
acid, phthalic acid, protocatechuic acid, catechol, and gentisic asid,
could not be detected directly by GC–MS, an analytical derivatization
procedure was used to detect these compounds with GC–MS;
thesecompoundswere subjected to trimethylsilylation (TMS).