Question

Blood react with Drabkins reagent to form a stable coloured product is __________.

• A. Acid haematin
• B. Methaemoglobin
• C. Cyanmeth haemoglobin
• D. All of these

Answer 1

Answer:

C. Cyanmeth haemoglobin

Cyanmethemoglobin Method

• The Principle: This is the internationally recommended method for the estimation of hemoglobin (Hb). The blood sample is diluted with Drabkin's reagent (or cyanmethemoglobin reagent).
• Chemical Reaction: The hemoglobin in the blood is oxidized by the potassium ferricyanide present in the reagent to form methemoglobin. This methemoglobin then reacts with potassium cyanide to form the stable complex cyanmethemoglobin.
• Drabkin's Reagent Composition: The solution contains:
  • Potassium Ferricyanide: Oxidizes ferrous iron (Fe2+) to ferric iron (Fe3+).
  • Potassium Cyanide: Converts methemoglobin to cyanmethemoglobin.
  • Potassium Dihydrogen Phosphate: Acts as a buffer to maintain pH.
• Characteristics of the Product:
  • Stability: The resulting cyanmethemoglobin complex is highly stable, making it ideal for accurate spectrophotometric measurement.
  • Absorbance: The absorbance of this stable complex is measured at 540 nm using a spectrophotometer or colorimeter.
• Advantages: This method measures almost all forms of hemoglobin present in the blood, including oxyhemoglobin, methemoglobin, and carboxyhemoglobin. However, it does not measure sulfhemoglobin.
• Safety Note: Due to the presence of potassium cyanide in the reagent, it must be handled with extreme care and proper laboratory safety protocols.