Page 227 - Applied Pharmacognosy
P. 227
Methods of injection
Methods of injection differ according to:
the type of samples & type of column
A-Paked column
1-Gas sample
•Air quick fit micro syringe to draw sample
•Gas switching valve system
•In environmental analysis: draw volume of air on tube containing
adsorbent
i. Heating for thermal desorption
ii.elution with solvent e.g. carbon disulfide, hexane, trichloro ethylene,
chloroform.
iii. heating in helium or nitrogen, cooling condensation of vapor and
collection in cold trap, automatic injection to column (purge & trap system )
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