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Which of the compounds elute fast in reverse phase chromatography?
Compounds that are non-polar elute faster in reverse phase chromatography as the stationary phase is non-polar and retains polar compounds longer. Polarity of the compound determines its retention time in reverse phase chromatography.
What would have been the result if a large quantity of petroleum ether alone were used as the eluent in either of the experiments described in column chromatography?
petroleum ether is a lot less polar than solvents like MTBE and the hexanes. so if the stationary phase is a lot more polar than the solvent then the components of the mixture that were added to the column to be separated will get stuck in the stationary phase
Why column chromatography doesn't separate polar compounds?
Column chromatography does separate polar compounds. Use EtOAc : MeCN : MeOH : water (relative volumes, not percentages) 60 : 20 : 20 : 20 60 : 15 : 15 : 15 60 : 10 : 10 : 10 70 : 10 : 5 : 5 70 : 5 : 2.5 : 2.5 70 : 2.5 : 1.25 : 1.25 If streaking occurs, or if you are trying to purify an acid with limited solubility in these systems, it sometimes helps to add 0.5% triethylamine. Reference: external link
How does the polarity of the stationary phase affect the separation of compounds?
The polarity of the stationary phase is critical in determining the interactions between the compound and the stationary phase. Compounds with similar polarity to the stationary phase will interact more strongly and be retained longer, leading to better separation. Conversely, compounds that are less polar than the stationary phase will elute faster.
Why derivatisation is used on some chemicals and not others?
Derivatisation is used to improve seperation, thermal stability to increase volatility of polar compounds, also to make these compounds less reactive in the column.
What is the elution order of compounds in column chromatography?
In column chromatography, compounds elute in order of increasing polarity. This means that less polar compounds will elute first, followed by more polar compounds.
Which of the compounds elute fast in reverse phase chromatography?
Compounds that are non-polar elute faster in reverse phase chromatography as the stationary phase is non-polar and retains polar compounds longer. Polarity of the compound determines its retention time in reverse phase chromatography.
How does the order of elution on a TLC plate compare between different compounds?
The order of elution on a TLC plate varies between different compounds based on their polarity. More polar compounds tend to move slower and elute later, while less polar compounds move faster and elute earlier.
Do alkenes elute before alkanes in gas chromatography?
Usually, but not always. Depends on the bond position and polarity of the column. Alkenes are less likely to elute first on polar columns.
How the polarity of a compound will affect on both normal phase and reverse phase mode chromatography?
In normal phase chromatography, polar compounds are retained more strongly due to interactions with the polar stationary phase, while nonpolar compounds elute first. In reverse phase chromatography, the opposite is true: polar compounds elute first because they have less interaction with the nonpolar stationary phase, while nonpolar compounds are retained more strongly.
If the column is polar then what types of illution first polar or non-polar?
if the column is polar then non polar ellute first because of its less interaction with that of stationary phase.
What would have been the result if a large quantity of petroleum ether alone were used as the eluent in either of the experiments described in column chromatography?
petroleum ether is a lot less polar than solvents like MTBE and the hexanes. so if the stationary phase is a lot more polar than the solvent then the components of the mixture that were added to the column to be separated will get stuck in the stationary phase
What is difference between gc and hplc?
gas chromatographt (GC) and High Performance Liquid Chromatography (HPLC) are different , and to understand why you must think about what chromatography is: Chromatography in its simplest form is like putting ink on blotting paper and watching the colours separate. Liquid chromatoraphy uses a "column" which is made from bare or bonded silica, it separates a mixture of compounds by how polar they are. You can use a gradient of different solvents. GC also uses a column, but it is a capillary column and instead of using a liquid to carry your mixture which needs to be separated it uses a carrier gas, like nitrogen. You can vary the temperatures in both LC and GC to aid better resolution. GC is used for more volatile compounds and LC is used more less volatile. HPLC usually refers to reversed phase, normal phase is where the column is vare silica which is very polar. Bonded silica is bonded with hydrocarbons which is non polar. The thing to remember is that "like attracts like" so if the column in non polar, the compound to elute first will be the most polar. To summarise, they are both separation techniques, one uses gas and the other liquid. You would choose which one to uese depending on how volatile the compounds which you want to separate are. Vishal Bobade NCL,Pune
Why column chromatography doesn't separate polar compounds?
Column chromatography does separate polar compounds. Use EtOAc : MeCN : MeOH : water (relative volumes, not percentages) 60 : 20 : 20 : 20 60 : 15 : 15 : 15 60 : 10 : 10 : 10 70 : 10 : 5 : 5 70 : 5 : 2.5 : 2.5 70 : 2.5 : 1.25 : 1.25 If streaking occurs, or if you are trying to purify an acid with limited solubility in these systems, it sometimes helps to add 0.5% triethylamine. Reference: external link
How does the polarity of the stationary phase affect the separation of compounds?
The polarity of the stationary phase is critical in determining the interactions between the compound and the stationary phase. Compounds with similar polarity to the stationary phase will interact more strongly and be retained longer, leading to better separation. Conversely, compounds that are less polar than the stationary phase will elute faster.
Why derivatisation is used on some chemicals and not others?
Derivatisation is used to improve seperation, thermal stability to increase volatility of polar compounds, also to make these compounds less reactive in the column.
Is ionic compounds polar or non-polar?
Ionic compounds are non-polar because they consist of ions (charged particles) held together by electrostatic forces. These compounds do not have a separation of charge within the molecule, which is characteristic of polar compounds.
