Estimation of Sodium
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ESTIMATION OF SODIUM - COLORIMETRIC METHOD
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Principle
- Sodium is quantitatively precipitated as uranyl magnesium sodium acetate and the excess of uranyl salt reacts with potassium ferrocyanide to produce a brownish color. The intensity of the color is inversely proportional to the sodium concentration in the sample.
Uranyl ions + Mg ions + Na+ → UranylMgNa Precipitate
Free Uranyl ions + K4Fe(CN)6 → Brown colored complex.
Reagents
- Precipitating reagent
- Acid Reagent
- Color reagent
- Sodium standard (150 mmol/l)
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Reagent
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S
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T
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Standard
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0.01ml
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-
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Serum
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-
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0.01ml
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Precipitating reagent
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0.50ml
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0.50ml
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Mix well and allow to stand at room temperature for 5 minutes. Then centrifuge at 3000 rpm for 5 minutes to obtain a clean supernatant.
II. Color development
- Pipette into clean, dry test tubes labelled blank (B), standard (S), and test (T) as follows:
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S.No
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Reagents
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B (ml)
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S (ml)
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T (ml)
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1.
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Supernatant from above step
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-
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0.01
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0.01
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2.
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Precipitating reagent
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0.01
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-
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-
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3.
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Acid Reagent
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0.50
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0.50
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0.50
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4.
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Colour reagent
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0.05
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0.05
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0.05
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5.
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Deionised water
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2.00
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2.00
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2.00
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- Mix well and allow the reaction mixture to stand at room temperature for 5 minutes. Then measure the absorbance of blank (B), standard (S) and test (T) against distilled water at 530nm or with a green filter in a photoelectric colorimeter within 10 minutes.
Calculations
Sodium (mmol/L) = (O.D of B (-) OD of T / O.D of B (-) OD of S) 150 mmol/l
Result
- The sodium content of given serum = mmol / l or meq / l
Clinical Significance
Elevated sodium level is mainly found in conditions like
- hyperadrenalism (Cushing’s syndrome).
- Dehydration.
Low sodium level is found in the following conditions:
- hypoadrenalism (Addison’s disease),
- severe polyuria,
- Metabolic acidosis
- Diarrhoea
- Renal diseases in which sodium reabsorption is defective.
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Last modified: Monday, 4 June 2012, 6:00 AM
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