Method development for the measurement of quinone levels in urine

A method was developed for the quantification of 1–4 ring quinones in urine samples using liquid–liquid extraction followed by analysis with gas chromatography–mass spectrometry. Detection limits for the ten quinones analyzed are in the range 1–2 nmol dm−3. The potential use of this approach to monitor urinary quinone levels was then evaluated in urine samples from both Sprague-Dawley rats and human subjects. Rats were exposed to 9,10-phenanthraquinone (PQ) by both injection and ingestion (mixed with solid food and dissolved in drinking water). Urinary levels of PQ were found to increase by up to a factor of ten compared to control samples, and the levels were found to depend on both the dose and duration of exposure. Samples were also collected and analyzed periodically from human subjects over the course of six months. Eight quinones were detected in the samples, with levels varying from below the detection limit up to 3 μmol dm−3.