Laboratory work 7. Urine biochemistry

Normal urine pH ranges from 4.8 to 7.0, averaging 6.0. Normal urine acidity depends mainly on the ratio of NaH₂PO₄ and Na₂HPO₄. The character of food influences the pH of the urine. pH changes in acidic and the alkaline side can be observed in various diseases.

A drop of urine is applied on a strip of indicator paper with the help of a glass stick. Determine the pH by comparing the resulting color with the color scale.

2. Detection of inorganic components of urine.Upon evaporation of the daily volume of urine there is dry residue in the amount of 47-65 grams; inorganic substances are 15-25 grams from it. The most important urine cations are Na⁺, K⁺, NH₄⁺, Са²⁺, Mg²⁺, anions are С1^-, SO₄^2-, Н₂РО₄^-, НРО^2-, РО₄^3-, НСО₃^-, СО^2-, С₂О₄^2-. Microelements can be presented in urine in small quantities.

2.1. Detection of chlorides in the urine.To 1 ml of urine add 5 drops of 5% solution of nitric acid to prevent precipitation of silver phosphate, which is soluble in nitric acid. Add 4-5 drops of 1% silver nitrate solution. White curdy precipitate falls.

2.2. Detection of phosphates in the urine.Alkaline earth and alkali metals phosphates are found in the urine.

3-5 ml of urine are alkalized with a few drops of ammonia solution. Wait for 2-3 minutes to complete precipitation of calcium, magnesium phosphates, and magnesium-ammonium phosphate. The precipitate is filtered and the filtrate containing soluble phosphates of sodium and potassium is preserved. Transpose filtering funnel with sediment on the filter into another test tube, rinse precipitate 2 times with distilled water and dissolve it on the filter in 1-2 ml of 10% nitric acid solution. Add 1 ml of ammonium molybdate solution to nitric acid solution and heat. There is yellow crystalline precipitate of ammonium phosphomolybdate. To the saved filtrate add dropwise magnesian mixture. White crystalline precipitate MgNH₄PO₄ is formed. Soluble sodium and potassium phosphate (NaH₂PO₄, КН₂РО₄, К₂НРО₄) are precipitates in this form.

2.3. Detection of calcium and magnesium in the urine.Calcium and magnesium are excreted by intestine, to a lesser extent - by the kidneys. Put 1 ml of urine in the test tube; add 2 drops of 10% acetic acid solution and 3-5 drops of a saturated ammonium oxalate solution, then mix. The white crystalline precipitate of calcium oxalate is filtered. To the filtrate add 4-5 drops of 10% ammonia solution (to an alkaline reaction to litmus). Double phosphate of magnesium and ammonium gradually precipitates (in the form of turbidity):

2.4. Detection of ammonium salts in the urine.Pour 2 ml of urine and 1 ml of lime milk in the test tube. To the opening of the test tube bring moistened with water litmus paper, without touching it to the walls of the test tube. After some time, litmus paper turns blue due to the release of ammonia.

3. The organic components of urine.The organic components of urine include pyruvic acid, urinary pigments, urea, creatinine, uric acid, amino acids, and others. Also some enzymes, vitamins, hormones are excreted in urine. The pathological components of urine are protein, glucose, ketone bodies, bile pigments and blood, homogentisic acid and phenylpyruvic acid.

Date: 2016-04-22; view: 864