6460 triple quadrupole lc ms system

The analytical procedures of the sample extraction for water and sediment and PFAS analysis were performed as described elsewhere [36 (link),37 (link),38 (link)]. Extracted samples were analyzed using high-performance liquid chromatography coupled to tandem mass-spectrometry (6460 Triple Quadrupole LC/MS System, Agilent Technologies, Santa Clara, CA, USA). Betasil C18 LC column (50 × 2.1 mm, 5 µm particle size, Thermo Fisher Scientific, Waltham, MA, USA) and Hypersil Gold pre-column (10 × 2.1 mm, 5 µm particle size, Thermo Fisher Scientific, Waltham, MA, USA) were used as analytical and guard columns, respectively. The branched isomer concentration of PFHxS and PFOS (i.e., B-PFHxS and B-PFOS) was estimated using the response factors of the respective linear isomers (i.e., L-PFHxS and L-PFOS, respectively).
In total, 4 water and 44 sediment samples were analyzed. Procedural blanks were applied in duplicate for each sediment core batch (n = 6) and once for each duplicate water sample (n = 4). The method detection limits (MDLs) were determined at an S/N of 3, and ranged 0.04–0.05 ng L⁻¹ for water and 0.03–0.4 µg kg⁻¹ dry weight (dw) for sediment.

Chromatographic separations were performed on a 100 × 2.1 mm Phenomenex Kinetex C18 column (Kinetex) using the 1290 Infinity LC system (Agilent). The mobile phase was composed of solvent A: 0.1% formic acid in Milli-Q water, and B: 0.1% formic acid in acetonitrile. Analytes were eluted with a gradient of 5–95% B (1–15 min), 95% B (1520 min), and then returned to 5% B for 5 min to re-equilibrate between injections. Injections of 20 μL into the chromatographic system were used with a solvent flow rate of 0.10 mL/min.
Mass spectrometry was performed on the 6460 triple quadrupole LC/MS system (Agilent). Ionization was achieved by using electrospray in the positive mode and data acquisition was made in multiple reactions monitoring (MRM) mode. Two MRM transitions were used for GSK620: m/z 325→ 169 and 325→ 247 with fragmentor voltage of 85V, and collision energy of 17 and 5 eV, respectively. Analyte signal was normalized to the internal standard and concentrations were determined by comparison to the calibration curve (0.5, 5, 50, 250, 500, 2000 nM). GSK620 brain concentrations were adjusted by 1.4% of the mouse brain weight for the residual blood in the brain vasculature as described by Dai et al.(59 (link)).