Propylene Glycol Dicaprylate/Dicaprate

Decanoic acid, mixed diesters with octanoic acid and propylene glycol [68583-51-7].
» Propylene Glycol Dicaprylate/Dicaprate is a mixture of the propylene glycol mono- and diesters of caprylic acid (C8H16O2) and capric acid (C10H20O2), the diesters fraction being predominant.
Packaging and storage— Preserve in well-closed containers, and protect from moisture. No storage requirements specified.
B: Thin-Layer Chromatographic Identification Test 201
Test solution: 50 mg per mL, in methylene chloride.
Standard solution: 50 mg per mL, in methylene chloride.
Application volume: 10 µL, as streaks.
Developing solvent system: a mixture of ether and hexane (70:30).
Spray reagent— Prepare a 0.1 mg per mL solution of rhodamine 6G in alcohol.
Procedure— Develop the chromatogram over a path of 15 cm, and dry the plate in a current of air. Spray the plate with Spray reagent, and locate the spots on the plate by examination under UV light at a wavelength of 365 nm: the RF values of the principal spots obtained from the Test solution correspond to those obtained from the Standard solution.
C: It meets the requirements of the test for Fatty acid composition.
Acid value 401: not more than 0.2.
Hydroxyl value 401: not more than 10.
Iodine value 401: not more than 1.0.
Peroxide value 401: not more than 1.0.
Saponification value 401: between 310 and 335.
Unsaponifiable matter 401: not more than 0.5%, determined on 5.0 g.
Fatty acid composition 401 Propylene Glycol Dicaprylate/Dicaprate exhibits the composition profile of fatty acids shown in the following table, as determined in the section Fatty Acid Composition under Fats and Fixed Oils 401.
Carbon-Chain Length Number of Double Bonds Percentage (%)
6 0 2.0
8 0 50.0–80.0
10 0 20.0–50.0
12 0 3.0
14 0 1.0
Water, Method Ia 921: not more than 0.1%, using a mixture of methanol and methylene chloride (1:1) in place of methanol in the titration vessel.
Total ash 561: not more than 0.1%.
Alkaline impurities— Dissolve 2.0 g of Propylene Glycol Dicaprylate/Dicaprate in a mixture of 1.5 mL of alcohol and 3.0 mL of ether. Add 0.05 mL of bromophenol blue TS. Not more than 0.15 mL of 0.01 N hydrochloric acid is required in order to change the color of the indicator to yellow.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Hong Wang, Ph.D.
(EM205) Excipient Monographs 2
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 1325
Pharmacopeial Forum: Volume No. 33(5) Page 974