GC Determination of Esters of Fatty Acids with Different Carbon Chains in Pearlescent Agents

GC was applied to the determination of esters of fatty acids with different carbon chains in pearlescent agents. The sample (0.200 0 g) was refluxed with 5 mL of 0.5 mol·L-1 KOH methanol solution for 60 min, and 20 mL of 140 g·L-1 boron trifluoride methanol solution were added to the reaction mixture for derivatization. The derivates were separated on INNOWAX-1 capillary column (30 m×0.25 mm, 0.25 μm) and determined by FID. Standard solutions of methyl palmitate and methyl stearate were analyzed by the proposed method, giving linear relationships between values of peak area and mass concentration of the 2 esters in the same range of 0.1-20 g·L-1, with same detection limits (3S/N) of 4 μg·L-1. Recovery was tested by addition of the above mentioned 2 standards at 3 concentration levels, giving values of recovery in the ranges of 98.0% to 99.5% and 97.8% to 98.9% respectively, with same RSD′s (n=6) of 0.08%. In analyzing samples of 6 different batches, values of conversion rate of derivatization calculated were higher than 97.5%.