How does chromatography work?
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What Is It??\nHello, everyone, and welcome to the wonderful world of chromatography! What is chromatography, you ask?? Well, quite simply, it is a broad range of physical methods used to separate and or to analyze complex mixtures. The components to be separated are distributed between two phases: a stationary phase bed and a mobile phase which percolates through the stationary bed. \n  \n  \nHow Does It Work? Like Magic!\nA mixture of various components enters a chromatography process, and the different components are flushed through the system at different rates. These differential rates of migration as the mixture moves over adsorptive materials provide separation. Repeated sorption/desorption acts that take place during the movement of the sample over the stationary bed determine the rates. The smaller the affinity a molecule has for the stationary phase, the shorter the time spent in a column.
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Chromatography is a means of separating molecules in a solution.  A very widely used technique is high-performance liquid chromatography (HPLC) which can use dozens of different separation columns to separate anything from small molecules to very large proteins, DNA and RNA.  In addition, the different fractions coming off the column can be collected and purified.  An example is that one can load spider venom onto the column, and each fraction collected and tested, and this way you can find out how many different toxin and poisons are present, what they are, and what the relative abundance of each are.
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Isopycnic = Equal density\n\nIsopycnic centrifugation depends solely upon the the buoyant density of the particle and not its size or shape and is independent of time. The size of the particle affects only the rate at which it reaches its isopycnic position in the gradient. The technique is used to separate particles of similar size but of differing density. Hence, soluble proteins, which have very similar density cannot usually be separated by this method whereas subcellular organelles and peroxisomes can be effectively separated.\n\nThis is done using Caesium chloride density gradient. Molecules separate on the basis of EQUILIBRIUM POSITION, NOT by RATES of sedimentation. Each molecule floats or sinks to position where density equals density of CsCl solution. There is no net sedimenting force on molecules.\n\nVery useful for purifying nucleic acid species of different density; also in separating proteoglycans extracted from cartilage
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I believe you mean "titration".\n\nTitration is a way to measure the concentration of a dissolved substance by seeing exactly how much of a neutralizing substance you have to add to the mixture to bring it to a neutral concentration.  \n\nThis is usually done by adding drops of a neutralizing substance of known strength until the original solution becomes neutral.  By calculating exactly how much neutralizer was needed, you know the strength of the original mixture.
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Chromatography is a technique used to separate the different components in a mixture.\nThere are column chromatography and paper chromatography.\nChromatography is used to\n*separate and identify the components in petroleum\n*detect,separate and identify drugs in blood or urine sample\n*detect herbicides in vegetables\n*separate and identify amino acids\n*separate antibiotics from mushroom\n*separate colour pigments from plant tissues\n*identify inorganic substances in alloys or minerals
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Links at\n\nhttp://www.itt.edu/staff/boyter/links/index.html#CHEMISTRY_CHROMATOGRAPHY
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Electrophoresis is a process of seperation of molecules based on electric charge they possess using mild electric field in an electrolyte medium. Protein peptides for eg. can be separated by breaking the long protein chain using denaturing chemical such as beta-mercaptoethanol and treated with a detergent such as sodium dodycyl sulphate to render net negative charge to the molecules (peptides so broken). Now, sepration takesplace mainly on the basis of molecular weight of the peptide. U can use standard peptides/proteins to get a separation calibration curve. These are available commercially.
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Take a sample and run a chromatography.
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Freezing only works on a certain percentage mixture.  Chromatography on regular phase silica would work the best using a non polar hydrophobic solvent.
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It is a chemical that you keep at all times.  In a typical lab that would include acid, bases, certain organic solvents, etc.  You will also hear stock solutions which are solutions of these chemicals.  Do not confuse these with standard solutions which are solutions where the concentration is exactly known.
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you analyse the lowest first\na) to avoid contamination e.g. if you do highest first then, syringe will have traces of your original sample and thus giving you falsely higher result.\n\nb) using higher concentrations can sometimes "blind" the instrument to lower concentrations.
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I worked with HPLC starting in th days when it was called High Pressure instead of High Performance LC.  I used several chromatographs over a five or ten year period.  It is basically a column chromatograph which is scaled down and uses a pump to move the mobile phase.\nThere are some nice sites which can give you the basics.  In addition there is an on-line forum for asking questions.
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It doesn't if the substance that is being tested is a liquid.  If the substance is a solid, then you need water to facilitate the interaction between the substance and the litmus.
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For information on how to do the chromatography test choose from the following lists:\nhttp://search.yahoo.com/search?p=chromatography+test&prssweb=Search&ei=UTF-8&fr=ytff1-&x=wrt\nhttp://www.google.com/search?num=100&hl=en&lr=lang_en&q=chromatography+test&btnG=Search
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Because you mention Rf values, I assume you're asking specifically about Thin-Layer Chromatography.  Actually the molecular weight is a fairly minor factor in the Rf value.  Intermolecular interactions between the pigment in question and the solid phase and the mobile phase are the most important.  So it really comes down to the selection of the mobile phase, how polar, how acidic or basic in relation to the analyte (your pigment in this case).  pH of the mobile phase is critically important in that your pigment may ionize to a greater or lesser extent depending upon the pH, and this drastically changes the intermolecular interactions.  Stationary phase selection is also important.
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According to Wikipedia, "High performance liquid chromatography (HPLC) is a form of column chromatography used frequently in biochemistry and analytical chemistry. It is sometimes referred to as high pressure liquid chromatography, although this terminology is considered out-of-date and disapproved by many. HPLC is used to separate components of a mixture by using a variety of chemical interactions between the substance being analyzed (analyte) and the chromatography column."\n\nhttp://en.wikipedia.org/wiki/High_performance_liquid_chromatography
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I would have to guess that it involves the neutralization reaction of more than 2 substances.\n\nJust a guess