13c12 2 phe

Fifteen mono OH-PAH standards, namely two hydroxynaphthalenes (1- and 2-Nap), five hydroxyphenanthrenes (1-, 2-, 3-, 4-, and 9-Phe), three hydroxyfluorenes (2-, 3-, and 9-Flu), hydroxypyrene (1-Pyr), two hydroxychrysenes (1- and 6-Chr), 3-hydroxybenzo-[c]-phenanthrene (3-BcP), and 1-hydroxybenz[a]-anthracene (1-BaA) were purchased from Sigma-Aldrich (purity ≥ 97% for all standards; St. Louis, MO, USA) or AccuStandard (purity ≥ 97%; New Haven, CT, USA). Ten isotopically labeled internal standards, ¹³C₁₂-1-Nap, ¹³C₁₂-2-Nap, ¹³C₁₂-1-Phe, ¹³C₁₂-2-Phe, ¹³C₁₂-3-Phe, ¹³C₁₂-6-Chr, ¹³C₁₂-2-Flu, ¹³C₁₂-1-Pyr, ¹³C₁₂-3-BcP, and ¹³C₁₂-1-BaA, were purchased from Cambridge Isotope Laboratories (purity ≥ 99% for all; Andover, MA, USA). High performance liquid chromatography (HPLC)-grade water, methanol, toluene, and pentane were purchased from J.T. Baker (Center Valley, PA, USA), Fisher Scientific (Waltham, MA, USA), Avantor Performance Materials (Phillipsburg, NJ, USA), and Sigma-Aldrich (St. Louis, MO, USA), respectively. BGALA-RO β-glucuronidase from E. coli K12 liquid enzyme (activity: 140 units/mg protein) was purchased from Roche Diagnostics GmbH (Mannheim, Germany).