[Edward]

I want to find standard method for quantitative determination of nitrate and nitrite in biological sample (e.g.urine) and non-biological samples (vegetable, chinese medicine).  Are there any simple colorimetric method or instrumental methods (e.g. HPLC)?  I have an Agilent 1200 HPLC system without ion suppressor, etc for ion chromatography.  Is it possible to perform conventional HPLC to analyse inorganic ions such as nitrate and nitrite?  I heard that British Pharmacopeia has some standard methods but I don't have access to it.  Are there any other source of standard methods?
Could any experts please advise?  Thank you very much in advance.

[IITian]

Consecutive estimation of nitrate and nitrite ions can be made by electron paramagnetic resonance spectrometry

The basic reaction used in the present study for turning the EPR-silent Fe(dtc)3 to the EPR-active FeNO(dtc)2 complex:



(1)NO2(NO)+Fe(dtc)3→FeNO(dtc)2+…was described previously [34 and 37] and has been used directly for estimation of the N2O4 background concentration in air.

The consecutive estimations of nitrate and nitrite ions were based on:

1. quantitative liberation of NO gas in the reaction of nitrite ion with an acidic solution of FeSO4:



(2)NO2−+nFeSO4+mH2SO4→NO+…In aerobic systems NO gives NO2 (or N2O4). Both NO and NO2 are further trapped by Fe(dtc)3 to give Fe(NO)(dtc)2 according to reaction (1) [34. N.D. Yordanov, V. Terziev and B.G. Zheliazkowa. Inorg. Chim. Acta 58 (1982), p. 213. Abstract |  PDF (350 K) | View Record in Scopus | Cited By in Scopus (4)34 and 37];

2. the nitrate present in the acidic solution of FeSO4 quantitatively yields Fe(NO)SO4 in solution according to reaction (3):



(3)NO3−+nFeSO4+mH2SO4→Fe(NO)SO4+…Further addition of Nadtc to this solution gives the EPR-active Fe(NO)(dtc)2, which may be separated by extraction.