Figure 2. Detection of 22(OH)7DHC and 20,22(OH)₂7DHC in the pig adrenal, human epidermis and human serum.

The LC-MS spectra were measured on fractions with retention times corresponding to either 22(OH)7DHC or 20,22(OH)₂7DHC that were pre-purified on a Waters C18 column (250 × 4.6 mm, 5 μm particle size) with a gradient of acetonitrile in water (40–100%) (see Materials and Methods). Extracted ion chromatograms are shown for human epidermis (A,D), serum (B,E) and the pig adrenal (C,F), and were measured using m/z = 383.3 [M + H − H₂O]⁺ (A) or 401.3 [M + H]⁺ (B,C) for 22(OH)7DHC, and m/z = 439.3 [M+Na]⁺ (D,E) or m/z = 417.3 [M + H]⁺ (F) for 20,22(OH)₂7DHC. Arrows indicate the retention times of the corresponding standards. Inserts show the mass spectra corresponding to the retention time of either 22(OH)7DHC (A–C) or 20,22(OH)₂7DHC (D–F).