Quantification of All-Trans Retinoic Acid by Liquid Chromatography-Tandem Mass Spectrometry and Association with Lipid Profile in Patients with Type 2 Diabetes.

Retinoic acids are vitamin A metabolites that have numerous essential functions in humans, and are also used as drugs to treat acne and acute promyelocytic leukemia. All-trans retinoic acid (RA) is the major occurring metabolite of retinoic acid in humans. This study provides a sensitive and specific liquid chromatography-tandem mass spectrometry approach in order to quantify RA in human plasma samples. The isolation of RA by hyperacidified liquid-liquid extraction using hexane and ethyl acetate resulted in a recovery of 89.7 ± 9.2%. The lower limit of detection was 20 pg·mL, and 7 point calibration displayed good linearity (R = 0.994) in the range of 50-3200 pg mL. Selectivity was guaranteed by the use of two individual mass transitions (qualifier and quantifier), and precision and accuracy were determined intraday and interday with a coefficient variation of 9.3% (intraday) and 14.0% (interday). Moreover, the method could be used to isolate RA from hyperlipidemic samples. Applying this method to plasma samples from patients with poorly controlled Type 2 diabetes significantly decreased RA plasma levels as compared to those of the healthy controls. In addition, RA concentrations were highly associated with increased low-density lipoprotein (LDL) and decreased high-density lipoprotein (HDL) cholesterol levels.