Type of fluid in the human body: measured by colour indicator

The volume of body fluids can be measured using indicators that are soluble in the fluid to be measured. The figure explains how to measure this volume. It is based on the principle of conservation of matter, which means that the total amount of matter after being mixed into the fluid is equal to the total amount of matter before it is injected.

Figure. Indicator dilution method for volume measurement

In the figure, a small amount of dye or any indicator is injected into the flask, wait until it dissolves evenly in the flask, then take a small amount to quantify the concentration chemically or photoelectrically. . Assuming no loss during the test, the total amount of indicator in the flask (volume B x concentration of substance B) will be equal to the amount of indicator introduced (volume A x concentration A). .

Then:

Volume B = (volume A x concentration A) / concentration B

For example, 10 ml of indicator with a concentration of 10 mg/ml is dissolved in flask B to give a solution of 0.01 mg/ml concentration, then the volume of flask B will be

1ml x 10mg/ml / 0,01mg/ml = 1000ml

Board. Measure body fluid volume.