D2 LAMP IN HPLC

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mohd
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D2 LAMP IN HPLC

DEAR SIR
HOW D2 LAMP WORKS IN AHPLC. HOW IT WILL ACTIVATE THE CHROMOPHORES IN A COMPOUND.
HOW MANY C18 CHAINS PRESENT IN A C18 COLUMN.(1/2/3/4) IF 4 THAN IS IT A C18 COLUMN.

Dr. Analytical
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The D2 lamp is a source of

The D2 lamp is a source of light for the ultraviolet region of the spectrum.  It works the same way as the source in a spectrophotometer.  Chromophores absorb light at certain wavelengths, and a detector measures the amount of light that is absorbed.  This reading produces the chromatogram that you see.  You should think of an absorbance detector in HPLC as just being a spectrophotometer with a continuous flow cell. 

An introductory book on analytical chemistry can give you more information about how chromophores interact with light.

The surface of a "C18" column contains the following bonded functional group.

Silica - O - Si(CH3)2 - C18H37

There are many of these chains on the surface ("billions and billions"), and they all have this 18 carbon chain.  It is a single layer.