Medical brain notes 25

  COLLECTION OF BLOOD   Aim   To collect blood sample.   Blood   Blood is one of the most common specimen studied in various sections of the lab in search of blood related disorders and infections.   Blood will clot within a few minutes after it is removed from the body unless an anticoagulant is used, which stops the process of clotting. The anticoagulated blood is also known as whole blood. For immunological studies unclotted blood is needed.   Plasma, the fluid portion of unclotted blood, is obtained by centrifugation. Plasma is needed in coagulation studies. Serum, the fluid portion of clotted blood is collected without adding any anticoagulant. The blood bank laboratories require clotted blood for blood grouping and also for cross matching. However, in a blood grouping EDTA anticoagulated blood can be used.   Anticoagulants   The anticoagulant prevents the blood from clotting. The commonly used anticoagulants are   ·   ...

  PREPARATION OF STARCH FROM POTATOES Aim   To prepare starch from potatoes.   Materials required   1.             Fresh raw potatoes   2.    Muslin cloth   Procedure   Take 100 g of raw potatoes, wash and peel. Cut the potatoes into small pieces. Mince them well in a blender with water. Remove the pulp material carefully and strain the pulp material through two layers of muslin cloth to remove the coarse particles. The filtrate obtained is opalescent (curdy). Keep it aside for about an hour. The starch will settle at the bottom. Decant the supernatant carefully and wash the starch with water repeatedly. Drain the water thoroughly and dry it in air. Weigh the dried material and calculate the amount of starch present in 100 g of potato.   Calculation   Weight of the potato                   ...

  PREPARATION OF CASEIN FROM MILK Aim   To prepare casein from milk.   Principle   Casein is the main protein found in milk and is present at a concentration of about 30-40 gms/lit. It is a phosphrous containing protein. Casein can be precipated from milk at its isoelectric pH of 4.8. Casein is insoluble in ethanol and ether and this property is used to remove unwanted fat materials from the preparation.   Materials required   1.             Milk -100 ml   2.             Sodium acetate buffer - 0.2 M, pH 4.8   3.             Ethanol              4.             Ether   5.        Muslin cloth   Procedure   100 ml of milk is taken in a 500 m...

  ESTIMATION OF PROTEIN (BIURET METHOD)   Aim   To estimate the amount of protein present in the given plasma sample.   Principle   The - CO - NH - group of protein forms a purple coloured complex with copper ion in alkaline medium. The colour intensity is measured at 540 nm. Since all proteins contain peptide bond, this method is fairly specific and there is little interference with other compounds.   Reagents required   Stock Biuret reagent   Dissolve 45g of Rochelle's salt (sodium potassium tartarate) in about 400ml of 0.2N sodium hydroxide and add 15g of copper sulphate. Stir it continuously until the solution is complete. Add 5g of potassium iodide and make upto 1 litre with 0.2N sodium hydroxide.  Biuret solution for use   Dilute 200ml of stock biuret reagent to 1 litre with 0.2N sodium hydroxide containing 5 gm of potassium iodide.   Stock standard solution   1g of protein (egg albumin) is weighed and made upto 100ml wit...

  ESTIMATION OF GLUCOSE (ORTHOTOLUIDINE METHOD)   Aim   To estimate the amount of glucose present in the given blood sample.   Principle   A solution of orthotoluidine in glacial acetic acid when treated with glucose produces a blue coloured product with an absorption maximum at about 640nm. The values obtained represent the true glucose level.   Reagents Required   1. Stock solution   l00mg of glucose is weighed and made upto 100ml with distilled water. Concentration of glucose = 1mg/ml   2. Working Standard solution   10ml of stock solution is diluted to 100ml with distilled water. Concentration of glucose = 100µg/ml   3. Orthotoluidine reagent   12.5 mg of thiourea and 12g of boric acid are dissolved in 50ml of distilled water by heating over a mild flame. 75ml of redistilled Orthotoluidine reagent and 375ml of analar acetic acid are mixed separately. The two solutions are mixed and the total volume is made upto 500ml with a...

  ESTIMATION OF CALCIUM (TITRIMETRIC METHOD)   Aim   To estimate the amount of calcium present in the given serum sample.   Principle   Calcium is precipated as calcium oxalate with ammonium oxalate. The precipate is washed with ammonia to remove the chloride ions. The washed precipate is then made to react with 1N sulphuric acid. The liberated oxalic acid is now estimated by titrating against standardised potassium permanganate.The amount of oxalic acid liberated is proportional to the amount of calcium.   Reagents Required   1. Ammonium oxalate solution (4 %)   4g of ammonium oxalate dissolved in 100ml of distilled water.   2. Ammonia solution (2%)   2ml of ammonia of specific gravity 0.88 is diluted to 100ml with distilled water.   3. Potassium permanganate (0.1N)   This is prepared by dissolving 3.16 g of potassium permanganate in 1 litre of distilled water.   4. Standard oxalic acid solution (0.1N)   It is prepar...