DIMITRIOS TSIKAS, Dimitrios TSIKAS, ANKE BÖHMER, ARNE TRETTIN, ARSLAN ARINÇ KAYAÇELEBİ

Acid-free synthesis of S-nitrosothiols at neutral pH by shock-freezing in liquid nitrogen

A laboratory method for the acid-free synthesis of S-nitrosothiols (RSNO) from NaNO$_{2}$ and thiols in aqueous buffer of neutral pH is reported. Equimolar amounts of NaNO$_{2}$ and thiol are added to a 100-$\mu $M Na$_{4}$EDTA-containing Na$_{2}$HPO$_{4}$ buffer (100 mM, pH 7.4). Samples are set into liquid nitrogen for 1 min and then thawed to room temperature or in an ice bath. Dependent upon the RSNO, repetition of the procedure may be required. This method may be of particular importance when the classical acid-based method fails or releases harmful gases such as H$_{2}$S.

Anahtar Kelimeler:

LC-MS, nitric oxide, nitrite, S-nitrosothiols

Acid-free synthesis of S-nitrosothiols at neutral pH by shock-freezing in liquid nitrogen

Keywords:

LC-MS, nitric oxide, nitrite, S-nitrosothiols,

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× 1 mm internal diameter, 3.5 µm particle size) at 35◦C. Electrospray ionisation in the positive mode (ESI+) was used with nitrogen (600 ◦
C, flow rate of 1000 L/h) as the desolvation gas. The capillary voltage was set to 0.8 kV and the ion source was kept at 150 ◦
C. Argon served as the collision gas (0.13 mL/min, 1.8× 10 −3
mbar). System operation, data acquisition, and data processing were accomplished with the software MassLynx V4.1 from Waters. 4. Conclusions
In summary, aqueous solutions of RSNO are best prepared by acidifying equimolar amounts of nitrite and thiols. Here an alternative laboratory method is described for the acid-free preparation of RSNO in sodium phosphate buffer of neutral pH by shock-freezing in liquid nitrogen. The method provides pH-neutral buffered solutions of