Physics, asked by mahisingh8195, 1 year ago

Principle of spectrophotometer in molecular biology

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Answered by anishkumar70
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Introduction about spectrophotometer

                                                    SPECTROPHOTOMETER

PRINCIPLE: A spectrophotometer is an instrument which is used to measure the amount of light that a sample absorbs. in it a beam of light is passing through the sample and then sample absorb the light and its measure the intensity of light which is reaches to a detector.

INSTRUMENTATION: it is a source of rediation . itscontains both deutrium[D] and hydrogen [H] lamps which emitts the light wavelength range 160-375 nm and produce UV rediations. here a tungsten lamp also employed for as a source of visible light.this lamp use the wavelength range 350-2500 nm . for the selection of wavelength a monochromator is used. monochromators contains the following component parts like , an entrance slit, a collimating lens , a dispersing device,a prism , a focusing lens , an exit slit. in which the sample and the reference sample are placed that must be transparent are called CUVETTES. in UV visible spectroscopy photomultiplier tubes are commonly used as a detector. it consist photoemmisive cathod , several dynode and an anode . photo multiplier are very sensitive to UV and visible rediation.


WORKING:                                       


This works on the principle of lambert beer's low .

its works on IR and visible range of light [100-780nm]

it measure absorbance or transmission of monochromic light by the test sample.                     T=l/b , A= log10 T 

where T= transmittance , A = absorbs

switch on the instrument before 10 min. of use 

now set the wavelength 

set the absorbance or transmittance with the help of blank.

now take the absorbance of test sample one by one.

PRECAUTION:

handle the cuvette carefully.

in each time equal amount of sample is added .

adjust the abosorbance or transmission with adjust button.

wash the cuvettes each time before and after use because a few part of earlier sample is lefted so wavelength measured not in perfect way its disturbs the measurement .

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