Question

Which method is used in diagnostic laboratories for blood and urine tests?
A. Chromatography
B. Distillation
C. Centrifugation
D. Sedimentation

Answer 1

Centrifugation is the technique which involves the application of centrifugal force to separate particles from a solution according to their size, shape, density, viscosity of the medium and rotor speed. Not only is this process used to separate two miscible substances, but also to analyze the hydrodynamic properties of macromolecules. More-dense components of the mixture migrate away from the axis of the centrifuge (move to the outside), while less-dense components of the mixture migrate towards the axis, i.e., move to the center.

Complete answer:
There is a correlation between the size and density of a particle and the rate that the particle separates from a heterogeneous mixture, when the only force applied is that of gravity. The larger the size and the larger the density of the particles, the faster they separate from the mixture. By applying a larger effective gravitational force to the mixture, like a centrifuge does, the separation of the particles is accelerated. This is ideal in industrial and lab settings because particles that would naturally separate over a long period of time can be separated in much less time.
In centrifugation, the mixture is spun at high speed and the denser particles are forced to the bottom and lighter stay at the top. This method is used in diagnostic laboratories for blood and urine tests.

Thus, the correct option is C.

Note:
Centrifugation has various other application such as:
(i) Separating chalk powder from water
(ii) Removing fat from milk to produce skimmed milk
(iii) Separating particles from an air-flow using cyclonic separation
(iv) The clarification and stabilization of wine
(v) Separation of urine components and blood components in forensic and research laboratories.