this method of separation is called gel, molecular sieve or size-exclusion mechanism of separation. ...
TRANSCRIPT
This method of separation is called gel, molecular sieve or size-exclusion mechanism of separation.
Size exclusionO
-O
O
O-
O-
O
A-2
B-
N+
N+
N+
N+
A-2
B-
Vertical ascending
A,BAB
Paper
Mobile phase
Tank
B A A,B
Vertical descending
A,BAB
Paper
Mobile phase
Horizontal
Analyte zone (A,B)
Paper
Mobile phase
Cotton piece
A B
The polar drugs are adsorbed temporarily on the polar stationary phase surface. The most common stationary phase used for this purpose is silica. Silica has a chemical composition similar to glass SiO2. xH2O
OH Si
OH
OH
OH
OH
Si
O
O
O
Si
OH
O
Si
OH
OH
Si
OHSi OH
Silicic acid
Silica
Adsorption
Partioning
OH
OH
CH3
CH3
CH3
CH3
m-Xylene Toluene
The carrier is a gas such as nitrogen or helium. The column is long to retain the
analyte longer and it is filled with polydimethylsiloxane particles or relevant
derivatives.
Si O SiO
CH3
CH3
CH3
CH3
Plastic cover
Stationary phase
Column pore
Capillary column
FID (flame ionisation detector)
+ ++ +
+++++
GC column
Flame
Ionised compounds
ECD (electron capture detector)
This detector has a radioactive element. The radioactive element can produce a rich field of electrons. Once the compounds contain electronegative elements such as halogens reach the electron field they will capture some of the electrons and this change in the electrical field will give a response proportion with the concentration of the halogenated analytes. This detector is widely used in the analysis of halocompounds such as pesticides and herbicides
Radioactive isotope
B-
B-
B-
B-
B- B
- B-
B-B
-B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-B
-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-
B-