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Why are the plates in column chromatography called 'theoretical plates'?
Wiki User
∙ 16y ago
The number of theoretical plates in a chromatography column is a measure of how "long" the column is - how well it separates. A "short" column will only separate large or heavy molecules, and the medium and light stuff is still mixed together in the last band. A "long" column will separate the little stuff better because there are more theorectical plates.
Picture a stack of sieves with smaller and smaller holes as the column gets "longer" and you've got the idea.
This "length" has virtually nothing to do with the physical length of the separating column. It is a function of the packing materials and solvents used during a separation.
Wiki User
∙ 16y ago
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What are the usp limits for the theoretical plates in gas chromatography?
There is no "limit" set by the USP, it depends on the molecules and what is reasonable. For example in HPLC, 2000 plates is typically what you would like to shoot for but if its a compound with low sensitivity and you need to see low levels you might inject more compound which would increase sensitivity but also probably affect peak shape and thus theoretical plates. The answer is it depends
What are the advantages and limitations of column chromatography over thin layer chromatography?
TLC. The mobile phase is a liquid, the stationary phase is a solid. Useful for seperating and comparing mobility of solids and some liquids dissolved in the mobile phase by their affinities to the solid phase relative to the mobile phase. GLC. The mobile phase ia s gas, the stationary phase is a liquid on a solid support. same concept as TLC. useful for seperating gases by their affinities to the stationary phase...the mobility can then be compared to known compounds for possible identification.
If your first distillate was 49 mole percent methanol how many theoretical plates were in your distillation setup?
There is quite a bit of missing information here.a. Lets assume your pressure is 1 atm.b. Lets also assume you are distilling methanol and water.c. Lets assume your theoretical plate efficiency is 100%d. Lets ALSO assume your initial concentration is 0.1 mol% methanol.Given these condition it takes about 1.25 theoretical plates to distill it to about 49 mol%.The number of plates depends heavily on the initial concentration.Working backwards from 49mol%, exactly one stage would place you at an initial concentration of about 8%. Exactly two would place you at about 1 mol%.See also the McCabe Thiele method: http://en.wikipedia.org/wiki/McCabe-Thiele_method
How can paper chromatography be used to separate pigments based on their chemical and physical properties?
It is an appropriate technique to use because it separates the pigments, so one can see which pigments are present, even if some pigments are normally hidden to the naked eye.
Plastic trays used for eating are commonly called what?
Plastic trays used for eating are commonly called simply "trays." Sometimes, however, plastic food trays are referred to as "plates" or "pizza plates."
Searching for the sources where you can buy Silica Gel TLC Plates for Column Chromatography?
Column Chromatography is best choice for if you are looking for Silica Gel TLC Plates for Column Chromatography. For more inquiry call on 9879203377.
Why it is said that number of theoretical plates should be high for a good efficiency?
In liquid chromatography the 'theoretical plates' number is a measure of the resolution between the peaks of different eluting substances. The higher the plate value the greater the separation. This is particular important as the load reaches the maximum the column is designed for.
What is the efficiency of packed columns in gas chromatography?
It is around 4000-6000 plates for a 2 meter column.
Where I can buy Silica Gel TLC Plates for Column Chromatography?
you can find these items in alibaba or sigmaaldrich website.
What height a fractional distillation column has?
The height of a column used in fractional distillation is dependent on the number of theoretical plates needed to sufficiently separate a mixture divided by the height equivalent to theoretical plate HETP. Nt=H/HETP
What is a column plate number?
It is the efficiency of the column. The larger the number, the more theoretical plates the column possesses; a typical well-packed column with a 5-micrometer particle size porous packing in a 15cm x 46 mm column should provide10,000-20,000 plates. sorry. I forgot to put a point in there. It should be 4.5 mm, not 45
What are the usp limits for the theoretical plates in gas chromatography?
There is no "limit" set by the USP, it depends on the molecules and what is reasonable. For example in HPLC, 2000 plates is typically what you would like to shoot for but if its a compound with low sensitivity and you need to see low levels you might inject more compound which would increase sensitivity but also probably affect peak shape and thus theoretical plates. The answer is it depends
What is the purpose of Reflux in an oil refinery?
The reflux is the return of top product condensate from a distillation column back to the top of the column where it is able to flow down the column aiding with cooling and thus condensation in the column. It increases efficiency and enables a lower amount of theoretical plates to be used in the column.
What are the advantages and limitations of column chromatography over thin layer chromatography?
TLC. The mobile phase is a liquid, the stationary phase is a solid. Useful for seperating and comparing mobility of solids and some liquids dissolved in the mobile phase by their affinities to the solid phase relative to the mobile phase. GLC. The mobile phase ia s gas, the stationary phase is a liquid on a solid support. same concept as TLC. useful for seperating gases by their affinities to the stationary phase...the mobility can then be compared to known compounds for possible identification.
What Variables that affect column chromatography?
Answer:The factors which affect the chromatography are:TemperaturePressureFlow rate of mobile phaseSample preparation
What is Ethiopia's writing system?
The Different Types of Chromatography There are four main types of chromatography. These are Liquid Chromatography, Gas Chromatography, Thin-Layer Chromatography and Paper Chromatography. Liquid Chromatography is used in the world to test water samples to look for pollution in lakes and rivers. It is used to analyze metal ions and organic compounds in solutions. Liquid chromatography uses liquids which may incorporate hydrophilic, insoluble molecules. Gas Chromatography is used in airports to detect bombs and is used is forensics in many different ways. It is used to analyze fibers on a persons body and also analyze blood found at a crime scene. In gas chromatography helium is used to move a gaseous mixture through a column of absorbent material. Thin-layer Chromatography uses an absorbent material on flat glass or plastic plates. This is a simple and rapid method to check the purity of an organic compound. It is used to detect pesticide or insecticide residues in food. Thin-layer chromatography is also used in forensics to analyze the dye composition of fibers. Paper Chromatography is one of the most common types of chromatography. It uses a strip of paper as the stationary phase. Capillary action is used to pull the solvents up through the paper and separate the solutes.
What are the various pressure bases in the US?
The Different Types of Chromatography There are four main types of chromatography. These are Liquid Chromatography, Gas Chromatography, Thin-Layer Chromatography and Paper Chromatography. Liquid Chromatography is used in the world to test water samples to look for pollution in lakes and rivers. It is used to analyze metal ions and organic compounds in solutions. Liquid chromatography uses liquids which may incorporate hydrophilic, insoluble molecules. Gas Chromatography is used in airports to detect bombs and is used is forensics in many different ways. It is used to analyze fibers on a persons body and also analyze blood found at a crime scene. In gas chromatography helium is used to move a gaseous mixture through a column of absorbent material. Thin-layer Chromatography uses an absorbent material on flat glass or plastic plates. This is a simple and rapid method to check the purity of an organic compound. It is used to detect pesticide or insecticide residues in food. Thin-layer chromatography is also used in forensics to analyze the dye composition of fibers. Paper Chromatography is one of the most common types of chromatography. It uses a strip of paper as the stationary phase. Capillary action is used to pull the solvents up through the paper and separate the solutes.
