Determination of cholesterol and cortisone absorption in polyurethane. I. Methodology using size-exclusion chromatography and dual detection.
A size-exclusion chromatographic method is described for measuring the absorption of the steroid-based lipids cholesterol and cortisone into Pellethane 2363, a polyurethane used in biomedical implants. The method uses refractometry and ultraviolet diode-array detection, with tetrahydrofuran as the mobile phase. Using an injection volume of 150 microliters, the lower limit of accurate measurement for cholesterol (refractive index detection) was 6 micrograms/ml with a lower limit of detection, based on a 2:1 signal-to-noise ratio, of 0.15 micrograms (1 microgram/ml). For cortisone (ultraviolet detection), the lower accurate limit was 0.6 micrograms/ml with a lower limit of 0.015 micrograms (0.1 micrograms/ml). The results show that after 44 h, 2037 micrograms/g cholesterol and 3131 micrograms/g cortisone were absorbed by the polyurethane. The method eliminates extensive sample manipulation and is sensitive to low levels of lipid in the presence of a high-molecular-mass synthetic polymer.
Dillon
J G
JG
Food and Drug Administration, Center for Devices and Radiological Health, Rockville, MD 20852.
Hughes
M K
MK
D000042:Absorption; D002784:Cholesterol / Q000737:chemistry*; D002850:Chromatography, Gel; D003348:Cortisone / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry*; D012031:Refractometry; D013056:Spectrophotometry, Ultraviolet
D011140:Polyurethanes; D002784:Cholesterol; D003348:Cortisone