Question

The ratio of potassium oxalate to ammonium oxalate in double oxalate mixture's ________.

• A. 2 : 3
• B. 1 : 3
• C. 3 : 2
• D. All of these

Answer 1

Answer:

A. 2 : 3

Composition of Double Oxalate Mixture

• The standard double oxalate mixture, often used as an anticoagulant in blood collection tubes (specifically for hematological studies like ESR and packed cell volume), consists of two specific chemical compounds: Potassium Oxalate and Ammonium Oxalate.
• These two salts are combined in a precise weight ratio to ensure optimal efficacy in preventing blood coagulation while minimizing the distortion of blood cells.
• The universally accepted ratio for this mixture is 3:2.

Key Technical Details

• Potassium Oxalate: This component acts by precipitating calcium, which is an essential factor in the coagulation cascade. However, it tends to cause cell shrinkage.
• Ammonium Oxalate: This component is added to counterbalance the shrinking effect of potassium oxalate on red blood cells. Ammonium oxalate tends to cause cell swelling.
• Synergistic Effect: By combining them in a 3:2 ratio, the cell-shrinking effect of the potassium salt and the cell-swelling effect of the ammonium salt cancel each other out, thereby preserving the morphological integrity of the blood cells for examination.
• Application: This mixture is commonly known as Wintrobe's Mixture, frequently employed in preparing samples for the Wintrobe method of Erythrocyte Sedimentation Rate (ESR) determination.