Be specific and be detail with each question Why are we adjusting the pH of our

Question

Be specific and be detail with each question

Why are we adjusting the pH of our sample? Why is a basic pH necessary?
-­ What is the difference between the ionized and un-ionized drugs? Which is most
important for our extraction?
-­ Why is it important to evaporate the organic layer at low heat?
-­ How is Rf value calculated?
-­ What are the key features of an efficient solvent system?
-­ Why are we using the two different systems?
-­ What is the purpose of the chosen spraying reagents?
-­ What main functional groups will be analyzed by the ATR-IR?

Explanation / Answer

1) samples are adjusting ph values because samples acidic and basic nature it damages the column so solution is turns into neutral, basic ph are preferred because the elution of samples through the column slightly late campared to acidic ph.

2) Some drugs are made up of several elements combined to make the drug which has no charge (neither plus or minus). If these drugs can be ionized, they can split into two parts. One of the parts carries a plus charge (+) while the other part has a negative charge (-). A simple example is table salt or sodium chloride (NaCl) which can become ionized in water. NaCl is an inorganic compound.
NaCl = Na+ + Cl-
Nonionized :
Other types of drugs such as organic compounds don't ionize. The molecules in their structures are stuck together in such a way that they do not separate into parts. An example of a nonionized compound is benzene.
Unionized :
unionized - being a member of or formed into a labor union; "organized labor"; "unionized workers"; "a unionized shop".

3) when mixed with sample and organic solvent after that extarct samples by evaporate the organic layer at low heat.

4) in chromatography Retardation factor can be calculate by using this formula

Rf value = Distance trvelled by component / Distance moved by solvent

5) Selection of solvents requires a balancing act between solvent and compound polarities. For most separations, the solvent should be less polar than the compounds. The compounds must also be soluble in the solvent so they are not permanently adsorbed. The elutropic series (order of polarity) for silica gel and alumina is as follows: hexane. petroleum ether etroleum ether is a generic name given to a mixture of pentanes, hexanes and heptanes. It does not contain any ethers of the R-O-R' structure.) < carbon tetrachloride < toluene < dichloromethane < chloroform < diethyl ether < ethyl acetate < acetone < propanol < ethanol < methanol < acetic acid < water.
In simple separations a single solvent (or solvent mixture) is used throughout the process. In complex separations, a series of increasingly polar solvents is used. By starting with a non-polar solvent, most of the compoundsshould remain adsorbed at the top of the column. Small systematic increases in solvent polarity will ideally elute these components one at a time.A large increase in polarity may cause all of the components to elute at once, as well as cause other problems with the column packing. Consequently, small polarity changes are accomplished by careful use of mixed solvents. For example, pure hexane may be used as the first solvent. This may be followed by a mixture of 90% hexane - 10% dichloromethane. Successive mixtures containing 20%, 50%, 80%, and 100% dichloromethane would complete the transition in polarity.

6) the spraying reagents are used in visualization and evalution of chromatograms in paper chromatography, colured fractions are observed visually, the components which are colorless themselves can show color by spraying a reagnt.

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