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:

1. handle the cuvette carefully.
2. in each time equal amount of sample is added .
3. adjust the abosorbance or transmission with adjust button.
4. 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 .

ADVANTAGES : Its works on high accuracy and reliability , 340-960 nm range, % T , absorbance, concentration, measuring ways , 10 nm bandwidth, 

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