Epa 610 pah mix

Extraction recoveries were quantitatively determined by an internal standard mix (ISTD) confirmed by two deuterated PAHs in phenanthrene (Phe-d₁₀) and pyrene (Pyr-d₁₀). Supelco EPA 610 PAH Mix was used as the reference standard for the target PAHs. All reagents were at least analytical reagent grade. Specific suppliers and purity grades were previously reported in Mundo et al. (2020) [28 (link)].

In this work, we used as authentic nitro-PAH standards a NIST SRM 2265 (polycyclic aromatic hydrocarbons nitrated in methylene chloride II), which contained 2-nitrofluoranthene (2-NFLT, CAS# 13177-29-2), 3-nitrofluoranthene (3-NFL, CAS# 892-21-7), 1-nitropyrene (1-NPYR, CAS# 5522-43-0), 2-nitropyrene (2-NPYR, CAS# 789-07-1), and 3-nitrobenzanthrone (3-NBA, CAS# 17117-34-9), among others. Their certified concentrations were 5.46 ± 0.15 µg mL⁻¹ (2-NFLT), 6.14 ± 0.13 µg mL⁻¹ (3-NFLT), 6.91 ± 0.27 µg mL⁻¹ (1-NPYR), 6.91 ± 0.27 µg mL⁻¹ (2-NPYR), and 4.39 ± 0.11 µg mL⁻¹ (3-NBA). Since SRM 2265 does not include 2-nitrobenzanthrone (2-NBA, CAS# 111326-48-8), this compound was purchased from Sigma-Aldrich (USA) (>99% purity) and added to that. Authentic standards for fluoranthene (FLT, CAS# 206-44-0), pyrene (PYR, CAS# 129-00-0), benzo[a]pyrene (BaP, CAS# 50-32-8), and benzo[a]anthracene (BaA, CAS# 56-55-3), among others, are included in the EPA 610 PAH mix, at 2000 µg mL⁻¹ each, in methanol: methylene chloride (1:1) (Supelco, USA). In this study, stock and analytical solutions were prepared by successive dilutions in acetonitrile (chromatographic and spectroscopic grade, J.T. Baker, USA).

For the B[a]P analysis, filters were extracted with a solvent mixture of toluene (Merck) and cyclohexane (Merck) (7:3) in an ultrasonic bath for 1 h, separated from undissolved parts by centrifugation (10 min, 3000 rpm), evaporated to dryness in a mild stream of nitrogen at 30 °C, and then re-dissolved in acetonitrile (Merck) [87 (link)]. The analysis was performed using Varian Pro Star high-performance liquid chromatography (HPLC, Varian, Victoria, Australia) with a fluorescence detector, which was programmed at eight different steps of excitation (λ = 234) and emission (λ = 500) to provide optimal detection. The mobile phase was a mixture of acetonitrile and water, and the flow rate was 0.55 mL/min. For separation, a Varian stainless-steel Pursuit 3 PAH column (3 µm, 4.6 × 100 mm) was used. Laboratory and field blanks were processed in the same way as real samples. For quality control and assurance, the analytical standard (Supelco EPA 610 PAH mix) and certified reference material (CRM NIST 1649b, Urban dust) were used [87 (link),88 (link),145 (link)].