2H-SIAM Reveals Transformation Products of 6PPD-Quinone in Water-Level Fluctuation Zone Soils
Description
The aims of this data is to identify potential TPs of 6PPDQ in the water-level fluctuation zones (WLFZs) by 2H-labeled 6PPDQ and 2H-SIAM pipeline. The bulk soil from WLFZ was collected after removal of surface debris from a depth of 0-20 cm on a campus near Nanhu Lake, Wuhan, China. Before use, the soil was air-dried to constant weight and sieved through a 2 mm mesh.
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Steps to reproduce
For the Non-Targeted Analysis (NTA), 2H-SIAM was employed to identify TPs of 6PPDQ. Briefly, 6PPDQ and 6PPD-d5 were each dissolved in ACE and then mixed separately with one-quarter of the bulk soil. After solvent evaporation, each mixture was combined with the remaining bulk soil to obtain 500 ng/g 6PPDQ and 500 ng/g 6PPDQ-d5 spiked soils, respectively. These concentrations fall within the range of 6PPDQ concentrations in roadside dust and soil reported in a recent review. The spiked soils were then placed in the WLFZ and separated from the native soil by a nylon mesh, as illustrated in Figure 1. After 90 days of incubation, the soils were harvested and air-dried at 60 °C to constant weight. Five grams of each soil sample was extracted with 50 mL of a mixture of ACE and HEX (1:3, v/v) using ultrasonic extraction, with OTP added as an extraction surrogate. Anhydrous Na2SO4 was used to remove residual water. The solvent was then exchanged to MeCN, and dichlorvos-d6 was added as an internal surrogate for instrument calibration. The extracts were concentrated to 0.5 mL under a nitrogen stream. Extracts from the 6PPDQ and 6PPDQ-d5 treatments were mixed at ratios of 1:3 and 3:1 to obtain Mix1:3 and Mix3:1 samples, respectively. The resulting samples were analyzed using UPLC-ESI-HRMS, consisting of an Ultimate 3000 (Dionex, Sunnyvale, CA, USA) coupled to a Q Exactive Orbitrap mass spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) equipped with a heated electrospray ionization (ESI) source. For untargeted recovery of 6PPDQ TPs from the soil, the following chromatographic conditions were used in the UPLC-ESI-HRMS analysis. A 5 µL aliquot of each sample was injected into the system equipped with a Thermo C18 column (5 µm, 4.6 × 250 mm). The mobile phases consisted of solvent A (water with 0.1% formic acid, FA) and solvent B (methanol with 0.1% FA). UPLC was performed at a flow rate of 1 mL/min and a column temperature of 25 °C, using the following linear gradient (%B over time in minutes): 10% at 0 min, 10% at 2 min, 90% at 12 min, 90% at 15 min, 10% at 18 min, and 10% at 20 min. Mass spectrometry was operated in profile mode with a scan range of m/z 60-900, a resolving power of 70,000 full width at half maximum (FWHM) at m/z 200, an automatic gain control (AGC) setting of 3 × 106, and a maximum injection time of 200 ms. The heated ESI source was configured with the following parameters: sheath gas flow rate, 40 arbitrary units (au); auxiliary gas flow rate, 20 au; spray voltage, 3.8 kV; and capillary temperature, 325 °C. Data included both MS1 and MS2 dataset.