Quantification of Phenanthrene in Environmental Samples

Samples (2 mL) for quantification of phenanthrene were each extracted three times with dichloromethane:methanol (9:1 v/v). Solvent extracts were evaporated to dryness under a gentle stream of high-purity nitrogen and the resultant residue reconstituted in 25 μL hexane. Phenanthrene was detected and quantified using a ThermoScientific TRACE 1300 gas chromatograph coupled to a dual ISQ LT mass-selective detector and flame ionization detector (GC/MS-FID). For this, reconstituted extracts were injected by programmed temperature vaporization (PTV) in splitless mode at 300 °C onto a DB-5 ms column (30 m × 0.25 mm inner diameter × 0.25 μm film thickness). The oven was at first held for 2 min at 60 °C, then ramped at 4 °C/min to 300 °C and held for an additional 15 min. Samples were run both in selective ion mode (SIM) and full scan (total ion count [TIC]) mode. Compounds were identified through full scan mass spectra in conjunction with retention time against authentic polycyclic aromatic hydrocarbon (PAH) standards (QTM PAH Mix [CRM47930]). Phenanthrene was additionally quantified in SIM (m/z 178) through response factors determined from 5-point concentration calibration curve of identical PAH standards.