Determination of the retinoid (E)-1,2,3,4-tetrahydro-1,1,4,4-tetramethyl-6-(1-methyl-2- phenylethenyl)naphthalene and its phenolic metabolite in human plasma by reversed-phase high-performance liquid chromatography

A rapid, sensitive and specific high-performance liquid chromatographic assay was developed for the determination in plasma of (E)-1,2,3,4-tetrahydro-1,1,4,4-tetramethyl-6-(1-methyl-2- phenylethenyl)naphthalene (1) and its phenolic metabolite (E)-4-[2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-2- methylethenyl]-phenol (2). An extraction procedure using protein precipitation and liquid-liquid extraction was combined with a simple column-switching technique. To minimize sample consumption, the assay was adapted to a sample volume of 200 microliters, which was sufficient for more than 90% of all determinations. The quantification limit was 100 ng/ml for 1 and 2, whereas the detection limits were 20 and 30 ng/ml, respectively. The recoveries for 1 and 2 were 91 and 94%, respectively, using ultraviolet detection at 280 nm. The assay was used to quantify both compounds in human plasma samples.