[Determination of nitrite in serum and tissue by oscillopolarography]

A method for determining nitrite in serum and placenta tissue by oscillopolaropgraphy is reported in this paper. Nitrite in 0.10 ml of serum or placenta homogenate reacts with sulfanilmide and N-1 (1-Naphthyl)-ethylendiamindihydrochloride in diluted hydrochloric acid medium to form an azo compound which can produce a sensitive reductive polarographic wave in ammonium alkaline medium. The wave height is directly proportional to the nitrite content, the method has a detection limit of 0.56 microgram/L (corresponding to the nitrite content of 0.61 mumol/L in serum or 0.22 microgram/g), RSD, of 6.1%-7.8% and recoveries of 92.0%-108.0% (mean value 100.6%). The method is sensitive, simple and can determine the nitrite directly without removal of the proteins in the samples.