Lc 20adsp

The water-soluble inorganic compounds (WSIC) of PM were measured by using ion chromatography (LC-20ADsp, SHIMADZU, Kyoto, Japan). One quarter of quartz filter was extracted with deionized water (10 mL) for 20 min, and the extractant was used for analysis. The cation and anion columns were Ion Pac CS12A and AS14A, respectively. An eluent solution mixture, Na₂CO₃ (8 mol/L) and NaHCO₃ (1 mol/L), was used for anion separation (flow rate of 1 mL/min), and methane sulfonic acid (20 mol/L) was used for cation separation (flow rate of 1 mL/min). The detected WSIC mainly includes Na⁺, NH₄⁺, K⁺, Ca²⁺, Mg²⁺, F⁻, Cl⁻, NO³⁻, and SO₄²⁻. The extractants were filtered using microporous membranes (0.22 mm pore size) to remove any insoluble materials [15 (link)].

Frozen nervous tissue samples were thawed. For E18 and E21, 4 tissue samples were then combined into one sample, and for P5, one tissue sample was taken as a single sample. All samples were homogenized in 120 μL 0.1 N HClO₄ with 3,4-dihydroxybenzylamine hydrobromide (5 pmol/mL) using an ultrasonic homogenizer (UP100H, Hielscher, Germany). The sample homogenates were then centrifuged for 15 min at 20,000 g and +4 °C and the supernatant was collected, in which DA and L-DOPA were measured.
High performance liquid chromatography separation was carried out on a reversed-phase column ReproSil-Pur, ODS-3, 4 × 100 mm with a pore diameter of 3 µm (Dr. Majsch GMBH, Entringen, Germany), at a temperature of +28 °C and a mobile phase speed of 1 mL/min, supported by a liquid chromatograph LC-20ADsp (Shimadzu, Kyoto, Japan) at 850 mV. Mobile phase consisted of 0.1 M citrate-phosphate buffer, 0.3 mM sodium octanesulfonate, 0.1 mM EDTA, and 8% acetonitrile (all reagents from Sigma, Saint Louis, MO, USA) (pH 2.58). DA and L-DOPA were determined using a fluorescent detector RF-20A (Shimadzu, Kyoto, Japan) at a wavelength of 285/316 nm. The peaks of the substances were identified by the time of their release into the standard solution.

The water temperature and the pH were measured using a pH meter (HM-20P; TOA DKK, Tokyo, Japan). The oxidation-reduction potential (ORP) were measured using an ORP meter (RM-20P; TOA DKK). The chemical oxygen demand (COD) concentration was determined using a HACH water quality analyzer (DR2500; HACH, Loveland, CO, USA). The suspended solid (SS) concentration was also measured using a glass fiber filter (0.4 μm, GB140; Advantec, Tokyo, Japan). The sulfate concentrations were determined by a high-performance liquid chromatography (HPLC) system (LC 20-ADsp; Shimadzu, Kyoto, Japan). The sulfide concentration was measured according to the standard methods published by the Japan Sewage Works Association⁷³ .