Synthesis and Characterization of S-Nitrosoglutathione

3-(Trimethoxysilyl) propyl methacrylate, methacrylic acid (MAA), ethylene dimethacrylate (EDMA), toluene, dodecanol, and azobis-(isobutyronitrile) (AIBN) were purchased from Sigma-Aldrich (MO, USA). Fused-silica capillaries with 530 μm i.d. × 720 μm o.d. were obtained from Polymicro Technologies™. Acetonitrile (ACN), methanol, acetone and formic acid of LC grade were also from Sigma-Aldrich (MO, USA). Ultra-Pure water was obtained using an in-house purification system. Mercury chloride (HgCl₂), ethylenediaminetetraacetic acid (EDTA), potassium dihydrogen phosphate (KH₂PO₄), mPEG-maleimide, sodium nitrite, glutathione (GSH) and ¹³C₂,¹⁵N-labeled G*SH were from Sigma-Aldrich (MO, USA) and were used without additional purification. Vivaspin 3000 MWCO membrane filters were from Sartorius Stedim (NA, USA). All sample preparations were carried out in the dark at 4°C unless otherwise stated. GSNO, ¹³C₂,¹⁵N-labeled G*SNO and 2-[1-(dimethylamino)ethanethioate]triphenylphosphine (derivatizing reagent) were synthesized as described earlier,^{18 (link)} and were confirmed by LC/ESI-HR-MS (see Figure S-1 and Supporting Information for details).