Oxyhemoglobin method

Spectrophotometric Oxyhemoglobin Method Bauld, W. S., and Greenway, R. M., Chemical Determinadon of Estrogens 30 227... 

Spectrophotometric Oxyhemoglobin Method, Measurement of Oxygen Consumption... 

IX. APPLICATIONS OF THE OXYHEMOGLOBIN METHOD FOR MEASUREMENT OF OXYGEN CONSUMPTION... 

Measurement of Oxygen Consumption by the Spectro-photometric Oxyhemoglobin Method. By Octavian Bdrzu. 227... 

B rzu, Octavian, Measurement of Oxygen Consumption by the Spectrophotometric Oxyhemoglobin Method. ... 

Kelm et al. [102] proposed a simple method of simultaneous spectroscopic detection of nitric oxide and superoxide based on NO-induced oxidation of oxyhemoglobin to methemoglobin and superoxide-mediated reduction of cytochrome c. 

The spectrophotometric methods make use of either the different absorption spectra of MHb and Hb, or of the decrease of NADPH2 absorbance at 340 or 366 mp. MHb has an absorption peak at 630 mp while oxyhemoglobin at 576 m x. By this, the absorbance of oxyhemoglobin appearing or the decrease at 630 mp may be a measure for MHbR activity (H23). 

Sims and Horn (S13) did not consider that the addition of urea to the sodium benzoate solution was of any advantage and observed speedy coupling at pH 6.0-7.0 without it. The addition of nitrite to the diazo blank was found to eliminate errors due to hemolysis, and colorimetric readings were made at 525 mp since this is the isobestic wavelength for oxyhemoglobin and methemoglobin. Urea-ethanol solution has also been used to facilitate rapid coupling of bilirubin with diazotized sulfanilic acid. Patterson et al. (PI) have been able to eliminate the cloudiness that tends to develop with this method by the addition of concentrated phenol. 

COHb is quite stable and its concentration does not change over a long period (up to 6 months) if the blood sample is stored in the dark and under sterile conditions. Blood levels of COHb are not expected to exceed 5% at ambient levels of CO. IPCS (1999) focuses on methods which can accurately measure COHb below 10%. A method which simply requires finger-prick blood is convenient for mass screening and is described in detail by Commins and Lawther (1965) in this method, the sample is diluted in ammonia solution, which is divided into two parts from one of these, CO is displaced by oxygen and the COHb containing part is placed in the sample beam of a spectrophotometer so that the instra-ment records the difference between the absorbance of COHb and oxyhemoglobin. 

The most important characteristic of oxyhemoglobin (Hb02) method is that it operates at low concentrations of molecular oxygen, which are physiological for a variety of cells. The great number of the reactions in which molecular oxygen participates is classified into three major groups (Keevil and Mason, 1978) ... 

Globin was prepared from crystalline bovine oxyhemoglobin by the method originally developed for Palemyssarda by Rossi Fanelli, Anto-nini, and Caputo (28) with our adaptation (20). The globin content was determined spectrophotometrically at 280 m/x with = 8.5. A sample of polyhistidine was obtained from the Biophysics Department, Weiz-mann Institute of Science. All other chemicals were purchased from commercial sources. 

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