2007-07-02 21:07:26 · 2 answers · asked by mallikarjuna D 1 in Science & Mathematics ➔ Chemistry
hi
i will help u ..........
the following are the reasons .......why hplc column...is bad.......k
* The accumulation of strongly retained material on an HPLC column can dramatically reduce its lifetime.
By modifying the packing surface, these retained materials can cause shifts in peak retention
-------------> loss of resolution
-------------> efficiency
-------------> degradation of peak shape
*Only limited number of bands can be accommodated because the time scale of the chromatogram is short
*Inapplicability to samples of similar size, such as isomers.
*At least 10% difference in molecular weight is required for reasonable resolution
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WHAT IS HPLC........???
The most widely used analytical separations technique
Utilizes a liquid mobile phase to separate components of mixture...............
uses high pressure to push solvent through the column
Popularity:
sensitivity
ready adaptability to accurate quantitative determination
suitability for separating nonvolatile species or thermally fragile ones.....................
Ideally suited for separation and identification of amino acids, proteins, nucleic acids, hydrocarbons, carbohydrates, pharmaceuticals, pesticides, pigments, antibiotics, steroids, and a variety of other inorganic substances...............
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MORE INFO........
Early LC carried out in glass columns
diameters: 1-5 cm
lengths: 50-500 cm
Size of solid stationary phase
diameters: 150-200 m
Flow rates still low! Separation times long!
Eureka! Decrease particle size of packing causes increase in column efficiency!
diameters 3-10 m
This technology required sophisticated instruments
new method called HPLC................
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ADVANTAGES...!!!!
Advantages of HPLC are result of 2 major advances:
stationary supports with very small particle sizes and large surface areas..............
appliance of high pressure to solvent flow............
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MORE ADVANATGES.........
Higher resolution and speed of analysis........
HPLC columns can be reused without repacking or regeneration................
Greater reproducibility due to close control of the parameters affecting the efficiency of separation...........
Easy automation of instrument operation and data analysis..........
Adaptability to large-scale, preparative procedures
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hope this is the best answer...........
all the best.......................
2007-07-02 21:14:31 · answer #1 · answered by Rohan 4 · 1⤊ 0⤋
Due to clogging or components which cannot be washed.
2007-07-03 11:27:06 · answer #2 · answered by ag_iitkgp 7 · 1⤊ 1⤋