Propylene glycol monocaprylate is a medium-chain fatty acid ester of polyhydric alcohols. It is widely used in drugs and cosmetics as a solubilizer and emulsifier. According to the United States Pharmacopeia and the National Formulary (USP 43-NF 38*), propylene glycol monocaprylate assay should be carried out with a 7.0 mm (I.D.) x 60 cm (length) column filled with L21 packing material and meets following requirements. The use of two KF-801 columns (8.0 mm (I.D.) x 30 cm (length) each) in series with its flow rate adjusted in-relative to the column I.D. confirmed the requirements were met.

System suitability requirements:
   Relative standard deviation (RSD) of monoester peak area : ≤ 2.0%

*The version at the time of the application acquisition.


Sample : 40 µL
40 mg/mL USP Propylene Glycol Monocaprylate Type I
1. Propylene glycol dicaprylate
2. Propylene glycol monocaprylate

Columns      : Shodex GPC KF-801 (8.0 mm I.D. x 300 mm) x 2
Eluent       : THF
Flow rate    : 1.1 mL/min
Detector     : RI
Column temp. : 40 °C