Urine relative density retention assay

Summary

gravimetric method

First, the experimental principle: urine hydrometer is a liquid hydrometer, can measure the specific gravity of urine under the specified temperature, the weight of the substance with the same volume of pure water at a certain temperature (4 ℃, 15.5 ℃) compared to the density obtained for the specific gravity of the substance being.

Test paper method

First, the experimental principle: the determination of urine than the density of the test paper containing polyelectrolyte methylene vinyl ether maleic anhydride, bromine musk oxalate blue indicator test paper invades the urine. The carboxyl group of the polymer electrolyte and the electrolyte reaction in urine, releasing H + so that the bromine musk oxalate blue indicator changes color.

Operation method

Urine relative density retention assay

Principle

Urine hydrometer is a liquid hydrometer that measures the specific gravity of urine at a specified temperature. The weight of the substance is the same as the volume of pure water at a certain temperature (4°C, 15.5°C) compared to the density obtained as the specific gravity of the substance being measured (specific gravity).



Test paper method: the determination of urine specific gravity of test paper containing polyelectrolyte methylene vinyl ether maleic anhydride, bromine musk muscovado phenol blue indicator test paper invades the urine. The carboxyl group of the polymer electrolyte reacts with the electrolyte in the urine, releasing H+ to make the bromo musk oxalate blue indicator change color.

Materials and Instruments

pycnometer Pycnometer

Move

(i) Gravimetric method

I. Experimental equipment: specific gravity meter (1) specific gravity cylinder (1)

Second, the experimental method:

1, fully mixed urine, along the wall of the tube slowly poured into a small measuring cup (no foam).

2, the hydrometer into the cup so that suspended in the center, do not touch the walls or bottom of the cup.

3, the hydrometer stopped after reading the urine concave tangent scale, that is, the specific gravity of the urine being measured.



(ii) test paper method

Experimental operations: test paper immersed in the urine to be measured in 2s, remove, remove excess liquid, in the natural light and the standard color plate color.

Caveat

Specific gravity method:1. Experimental Precautions：

（1） The urine densitometer must be calibrated, and pure water should be used to observe whether the specific gravity is standardized at the specified temperature.(2) Temperature correction, the temperature of the urine specimen will be inconsistent with the temperature indicated on the pycnometer, isothermal 3 ℃ should be increased by 0.001, every 3 ℃ lower will be subtracted from the result of 0.001.(3) urine containing Pr and GIV correction: every 10g / L protein will be less than the density of 0.003, 1Og / L glucose will be less than the density of 0.004(4) Treatment of salt precipitation, the urine specimen will be warmed to dissolve the salts and measured.Test paper method:Experimental precautions:1, alkaline urine can make the results low, strong acidic urine make the results high.

2， protein can cause indicator color changes.

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