Purification and Characterization of Sodium AOT

Most materials were used without further purification. Benzamide (BA) (99%), PIC (98%), NIC (98%), iNIC (99%), INH (≥99%), benzhydrazide (BHZ) (98%), isooctane (2,2,4 trimethylpentane, 99.8%), methanol (≥99.9%), activated charcoal (99.5%), chloroform (≥99.5%), deuterium oxide (99.9%), 2,2-dimethyl-2-si-lapentane-5-sulfonate sodium salt (DSS, 97%), monosodium phosphate (≥99.0%), disodium phosphate (≥99.0%), sodium hydroxide (≥98%), and hydrochloric acid (37%) were all purchased from Sigma-Aldrich. DPPC (≥99%) and DPPE (99%) were purchased from Avanti Polar Lipids. Sodium AOT (aerosol-OT, bis(2-ethylhexyl)sulfosuccinate sodium salt, ≥99.0%) was purchased from Sigma-Aldrich and was purified further as has been reported previously to remove any acidic impurities.^{30 (link)} Briefly, 50.0 g AOT was dissolved into 150 mL of methanol to which 15 g activated charcoal was added. This suspension was stirred for 2 weeks. After mixing, the suspension was filtered to remove the activated charcoal. The filtrate was then dried under rotary evaporation at 50 °C until the water content was below 0.2 molecules of water per AOT as determined by ¹H NMR spectroscopy. The pH was adjusted throughout this study using varying concentrations of NaOH or HC1 dissolved/mixed in either D₂O or H₂O depending on experimental requirements. NaOH or HC1 dissolved in D₂O is referred to as NaOD or DC1 respectively.