Sensitive determination of S-nitrosothiols in human blood by spectrofluorimetry using a fluorescent probe: 1,3,5,7-tetramethyl-8-(3',4'-diaminophenyl)-difluoroboradiaza-s-indacene.

S-Nitrosothiols (RSNO) have been proved to be potent smooth muscle relaxants and inhibitors of platelet aggregation. It has been reported as the best candidate for the endogenous storage and transport of nitric oxide (NO) in vivo. Sensitive determination of RSNO in biosamples seems to be of great significance. In this work, a novel spectrofluorimetric method is proposed to determine RSNO. An excellent fluorescence probe 1,3,5,7-tetramethyl-8-(3',4'-diaminophenyl)-difluoroboradiaza-s-indacence (DAMBO) is used to label RSNO. The derivatization reaction performs in aqueous medium at 30 degrees C for 15 min in the presence of 1.0 x 10(-4)mol L(-1) Hg(2+). The derivative is detected by fluorescence at an emission wavelength of 507 nm with excitation at 498 nm. The response is a linear function of concentration in the range of 6.0-400.0 x 10(-9)mol L(-1). The detection limit is 1.2 x 10(-10)mol L(-1) (S/N=3). The method is applied to determine RSNO in the blood of healthy persons and patients suffering from cardiovascular diseases. Recoveries of RSNO from spiked blood samples are between 97.52 and 102.81%. The studies indicate that the method presented here is rapid, simple, sensitive and feasible.