Figure 1
• Allows DI and splitless injections.
• Minimizes injection port
discrimination.
• Reduces loss of active compounds
formore accurate results.
The drilledUniliner
fi
liner providesmore accurate results.
environmental
Applications
note
Restek Corporation • (800) 356-1688 • (814) 353-1300 •
#59125
environmental
Improving throughput of semivolatileGC/MS analysis using a performance-
basedmeasurement system, Rtx
fi
-5Sil MS column, andUniliner
fi
inlet liner.
exposure to the injection port. This unique inlet liner can be used
for both direct and splitless injections. Because the column is
sealed to the liner with a press-tight connection, there is no chance
for any sample contact withmetal surfaces below the liner. The
small hole located on the side of theUnliner
fi
liner allows carrier
gas to be routed through the split vent line during the splitless
purge operation of the injection system. Because the drilled
Uniliner
fi
liner directsmore of the sample onto the column, less
discrimination of highmolecular weight compounds occurs.
Restek has developed aGC/MSmethod for analyzing semi-
volatile compounds (e.g., USEnvironmental ProtectionAgency
[EPA]Method 8270) that will help increase productivity in the
lab. The changes includemodifying the final extract volume,
using a drilledUniliner
fi
liner, optimizingGC analysis conditions,
andmodifying the calibration curve to offset the increased extract
volume. Following is an explanation of eachmodification.
1) Increase the final extract volume from 1mLto 5mL.
Increasing the final extract volumewill dilute the nonvolatile
material extracted from the sample, resulting in less contamina-
tion to the injection system and analytical column. This has the
potential to allow theGC/MS to stay in calibration longer, and to
reducemaintenance time and expense.Also, the increased extract
volumewill result in better recoveries of low-boiling compounds
that may be lost when the extract is concentrated to 1mL.
2) Replace the splitless inlet linerwith adrilledUniliner
fi
liner.
When the sample is injected into the injection port, it expands
and comes into contact with the bottom of the injection port. This
may cause adsorption or breakdown of the active compounds in
the sample.AdrilledUniliner
fi
liner (Figure 1) can be used in
place of a standard splitless liner to significantly reduce sample
Figure 2
The Rtx
fi
-5SilMS column, combinedwith a Siltek -treated drilledUniliner
fi
liner, exhibits excellent peak
shape and response for semivolatile compounds.
Rtx
®
-5SilMS, 30m, 0.25mm ID, 0.25µm (cat.# 12723)
Sample:
16µg/mL inmethylene chloride, IS@
8µg/mL
Inj.:
1 µLsplitless (hold 0.4min.),
DrilledUniliner
®
liner (cat.# 21054)
Inj. temp.:
300°C
Carrier gas:
helium, constant flow
Flow rate:
1mL/min.
Oven temp.:
35°C (hold 2min.) to 260°C@
20°C/min.,
to 330°C@ 6°C/min. (hold 1min.)
Det.:
MS
Transfer line temp.: 280°C
Scan range:
35–550amu
Ionization:
EI
Mode:
full scan
Analytical ReferenceMaterials used:
cat.#’s 31618, 31619, 31620, 31621, 31622, 31206, 31062, 31063
GC_EV00561
See page 3 for peak list.
22
