Fig 1.
Overview of naphthalene metabolism and excretion.
(A) Naphthalene metabolism showing the formation of both naphthol- and glutathione-derived urinary metabolites. (B) Chemical structures of targeted urinary naphthalene metabolites for LC/ESI-MS/MS analysis.
Table 1.
Parameters for LC/ESI-MS/MS analysis of urinary naphthalene metabolites and internal standards (IS).
Fig 2.
Extracted ion chromatograms of urinary naphthalene metabolites and deuterated internal standards.
(A) QC Sample #2. Naphthalene mercapturate, N-acetyl glutathione conjugate, naphthol glucuronide, and naphthol sulfate at 40, 5, 70, 20 ng on column, respectively. (B) Pooled urine sample from day 6–7 of exposure treatments (n = 3 animals). Calculated amounts of each metabolite on column were: 124.8, 7.9, 45.3, 25.9 ng for mercapturic acid, N-acetyl GSH, naphthol glucuronide and naphthol sulfate, respectively.
Table 2.
Estimated limits of detection (LOD), quantification (LOQ), and linearity of LC-MS/MS method for urinary naphthalene metabolite analysis.
Table 3.
Accuracy and precision results of quality control standards.
Fig 3.
Urinary excretion of major naphthalene metabolites during repeated naphthalene exposure at the OSHA short-term exposure limit (15ppm x 4 hrs daily) via inhalation.
(A) Average glutathione-derived metabolites excreted over entire exposure treatment (n = 2). (B) Average naphthol-derived metabolites excreted over entire exposure treatment (n = 2) (C) Total nmoles of quantified metabolite excreted over entire exposure treatment (n = 2). In all cases data represent the total nmoles of each metabolite excreted in a 24 hr period (ie concentration of metabolite (nmoles/ml) x mls urine collected for 24 hrs). Values are the mean of data obtained from 2 separate exposures (n = 2 cages) with 3 mice per cage.
Fig 4.
Naphthalene metabolite-specific percentages of total quantified metabolite during repeated naphthalene exposure treatments (15 ppm x 4hrs daily) via inhalation.