Chloride concentration of urine is dependent upon the amount of chloride present in the ingested food.
Volhard-Harvey Method:
PRINCIPLE:
The chloride in the urine is precipitated as silver chloride with a measured excess of silver nitrate The excess of silver nitrate is treated With ammonium. presence of Ferric Ammonium Sulphate as an indicator.
- 1 Concentrated HNO3,
- 2 AgNO3 solution,
- 3 Ammonium Thiocyanate,
- 4 Ferric Ammonium Sulphate ( Ferric alum ).
- 5 8% KMnO4 solution.
Procedure:
- To 5ml urine in a 100ml Erlenmeyer flask add lml Conc. HN03 and few drops of Ferric Ammonium sulphate, an indicator.
- If a red colour. is produced at this stage, add 800 KMnO4 solution drop by drOp with shaking until the colour disappears.
- Now add slowly 10ml Silver Nitrate solution, with continuous shaking. A White precipitate of silver chloride will be formed.
- Titrate the excess of silver nitrate left in the flask, with ammonium thiocyanate in the burette. The appearance of first permanent tinge of red brown indicates the end point.
- Note the burette reading and calculate the amount of chloride in the urine sample.
CALCULATIONS:
- Average volume of urine = 15OOml/day
- Volume of urine used = 5ml
- Volume of AgN03 used = 10ml
- Volume of NH4CNS used = ‘a’ ml Volume of AgNO3 used to precipitate the chloride in the urine = 10 -‘a = ‘b’ ml
- Amount of chloride precipitated by lml AgN03 = 10mg
- ‘b’ m1 AgNO3 Will precipitate = ‘b’ X 10 = ‘y’mg
- Therefore, 5m1 urine contains = ‘y’ mg Cl _ as NaCl
- 1ml urine will contain = ‘ y ’ mg Cl as NaCl/ 5
- 1500 ml urine will contain = ‘ y’ X 1500 / 5
- = ‘ C’ mg Cl as NaCl/day.
NORMAL RANGE:
Urinary Chloride = 7-10gm C1 as NaCl/ day.
Increased intake in diet. Drinking large volumes of water.
Decreased intake in diet. Due to excessive loss in vomiting, diarrhoea, and Profuse sweating.
During fasting. Nephritis associated with oedema.
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