Accurate Quantitation of the Phenyl Group in Methylphenylsilicone Oils by GPC-UV

Phenyl content is a crucial quality indicator for phenyl silicone oils, but the current 1H NMR method for determining it is still unreliable because of the possibility of interference from methylphenylcyclosiloxane or solvents such as toluene and xylene. Here, a novel method for the determination of the phenyl content in phenyl silicone oils for has been developed using gel permeation chromatography–ultraviolet detection (GPC-UV) analysis. Under optimized parameters, the standard curve has been established in the linear range of 5–1000 μg mL−1 with a squared correlation coefficient of more than 0.999, and a quantification limit of 0.972 μg mL−1 has been obtained. Potential interference-causing substances, such as methylphenylcyclosiloxane, toluene or xylene, and various silicone oils can be readily ruled out using the GPC-UV method. The phenyl content in 9 samples of phenyl silicone oil that were readily available was determined with a recovery in the range of 84.63–106.74%. The amount (0.613 mg g−1) of phenyl in sample H1 by GPC-UV was in good agreement with that (0.603 mg g−1) by the 1H NMR analysis.