This method is for determining the isomer distribution in C15 through C20 mono-substituted linear alkylbenzenes (LABs). The 6-phenyltridecane and 7-phenyltridecane isomers are not resolved from each other and are determined as a composite. The lower limit of detection for a single component is 0.1 mass-%.

Components other than linear alkylbenzenes are not normally determined by this method; however, an estimate of the total LAB content of the sample may be obtained by measuring the components present in the sample other than the LABs. A calculation is included to determine the number average molecular weight of the LABs in the sample, if needed.