The effect of chem. structure on the determination of the compound empirical formula was investigated. Alkenes, aromatic and polynuclear aromatic hydrocarbons, mixture of alkanes and alkenes, mixture of alkenes and polynuclear aromatic hydrocarbons, chlorohydrocarbons and bromohydrocarbons were chosen as testing compounds For the homologous hydrocarbons, any member of the homolog can be used as the ref. compound and its structure has no effect on the determination of empirical formula. For the mixture containing non-homologs such as alkenes and polynuclear aromatic hydrocarbons, the structure of ref. compound used has a significant effect on the result. The accuracy of the empirical determination will be poor if a non-homolog compound is chosen as ref. For the halogenated hydrocarbons, it is necessary that the ref. compound have a similar chem. structure (similar carbon skeleton and similar no. of halogen atoms) to those of testing compounds1

Key words: GAS CHROMATOGRAPHY, BROMINE, HYDROGEN, EXPERIENCES, MOLECULAR STRUCTURE, CHLORINE, CARBON, COMPOUNDS, PLASMA EMISSION SPECTROPHOTOMETRY