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GC Injectors
On-ColumnPTV Injector
• Inject Larger VolumesontoNarrowBoreColumns
• ConcentrateSampleandFocusPeaks
• Simpler thanSplit/Splitless Injectors
• LessBulky thanConventional PTVs
• Great for SemivolatileSamples
The On-Column PTV is a resistively heated precolumn, which is connected to your narrow bore column
with a special, electrically insulated split “T” inside the GC column oven. The 5 micron nonpolar phase
in the OCPTV precolumn has a high capacity to absorb high boiling compounds, and is stable at high
temperatures. Like in-tubeSPME, theprecolumndiscriminates in favor of highboilingsemivolatileanalytes,
concentrating them in the phase. Like the Split/Splitless injector, the OCPTV has a split vent and needle
valve for venting solvent while concentrating sample. Unlike a normal Heated Split/Splitless injector, the
OCPTV vents the solvent without expanding it to a gas. Therefore, the OCPTV is capable of larger liquid
injections than a regular heated split/splitless injector.
The GC operator injects sample via syringe through the on-column injection port with the split vent open
to vent the solvent. After injection and solvent venting, the precolumn heats upwhile the carrier gas lows
through it to sweep focused analytes from the precolumn to the analytical column. At this point, the
precolumn is hotter than the column oven. The temperature difference between the hotter precolumn and
cooler analytical column causes the analytes to focus on the analytical column, resulting in sharppeaks on
the chromatogram.
This chromatogramwasgeneratedby
an SRI GC equipped with anOCPTV
injector and an FID detector. A 25
meter narrow bore capillary column
was used to separate 100ppm diesel
rangeorganics (DRO).
Sample: diesel range organics (DRO) inhexane
Column: 25meterRXT-10.25µm
Carrier: hydrogen at 20psi
8690-0037
On-ColumnPTV Injector forGC
