Chlorpyrifos

Methyl parathion, glyphosate, chlorpyrifos, pirimicarb, and malathion were purchased from Sigma-Aldrich, Germany. Graphene oxide (GO) was purchased from Graphene Supermarket, USA. 1-Butyl-3-methylimidazolium hexafluorophosphate (IL), silver nitrate (AgNO₃), anhydrous trisodium citrate (Na₃C₆H₅O₇), potassium ferrocyanide (K₄[Fe(CN)₆]), potassium ferricyanide (K₃[Fe(CN)₆]), sodium phosphate monobasic monohydrate (NaH₂PO₄·H₂O), sodium phosphate dibasic heptahydrate (Na₂HPO₄·7H₂O), sodium sulfate (NaSO₄), sodium carbonate (Na₂CO₃), potassium chloride (KCl), sodium chloride (NaCl), and sodium nitrite (NaNO₂) were purchased from Sigma-Aldrich. All the chemicals used in this work were of analytical grade and used as received.

Chlorpyrifos (O,O-diethyl O-(3,5,6-trichloropyridin-2-yl) phosphorothioate) PESTANAL, purity ≥ 98% was purchased from Sigma-Aldrich (Poole, UK). It was dissolved in DMSO to make stock solutions of 100 mM and kept at −20 °C. Working solutions were freshly prepared and final concentrations were prepared in culture media with the DMSO concentration not exceeding 0.1%. All other chemicals and reagents were purchased from Sigma-Aldrich (Poole, UK) unless otherwise specified.

Lead acetate (Sigma-Aldrich) and cadmium chloride (Sigma-Aldrich) stocks were dissolved in water to prepare 20 mM stock solutions. BaP (Sigma-Aldrich) was dissolved in DMSO to prepare a 10 mM stock solution. Aldicarb (Sigma Aldrich) was dissolved in ethanol to prepare a 100mM stock solution. 6-hydroxydopamine (Sigma-Aldrich) was dissolved in water to prepare a 100 mM fresh stock solution before experiments. Chlorpyrifos (Sigma-Adrich) was dissolved in DMSO to prepare a 1 mM stock solution. Quinolinic acid (Sigma-Aldrich) was dissolved in DMSO to prepare a 10 M stock solution. AF64A (ethylcholine mustard aziridinium ion) was generated as previously described (Clement and Colhoun, 1975a (link), 1975b (link); Fisher et al., 1982 (link)). Briefly, acetylethylcholine mustard HCl (Sigma-Aldrich) was dissolved in water to prepare a 10 mM solution, NaOH 10 N was gradually added until reaching pH 11.5 and left for 20 minutes at room temperature. Concentrated HCl was added until reaching pH 7.5 and the solution was left to stand in room temperature for 1 hour. Stock solutions were preserved at −80 °C, and AF64A was prepared fresh before exposure assays. For the exposure experiments, K+ media was prepared with the following composition: 32 mM KCl, 51 mM NaCl, 13 μM cholesterol, 3 mM CaCl₂, and 3 mM MgSO₄, corresponding to approximately 90 mM chloride and expected pH of 6.5 (Boyd et al., 2009 (link); Meyer et al., 2010 (link)).