In: Chemistry
Experimental Organic Chemistry 1
-How do you know when you should use GC or HPLC?
-What's the difference between Reverse Phase HPLC and Normal Phase HPLC?
Answer
Q1. How do you know when you should use GC or HPLC?
Answer: GC is used for compounds that can change to gas phase on heating. (volatile compounds). Hence GC can be used for characterisation of compounds of low molecular weight which can remain stable at high temperatures. GC cannot be used for chatacterisation of compounds with high molecular weight. (e.g. proteins)
HPLC is used to volatile and non volatile compounds having low to high molecular weights as long as they are soluble in liquid phase. Thermal stability of a compound is not a concern as HPLC is performed at room temperature.
Q2. Differenece between reverse phase HPLC and Normal phase HPLC
Answer- In Normal phase HPLC, the mobile phase is completely organic. (non polar mobile phase). It is used to separate organic compounds.
In reverse phase HPLC, the stationary phase is hydrophobic and mobile phase is polar.( mixture of organic sovent and water). RP-HPLC is used to separate peptides, proteins.