The 7032A-LB Automated Tedlar® Bag Loop Autosampler

Tedlar® Bags are convenient for the analysis of VOCs and light gases.   Due to the semi-permeable nature of Tedlar, analysis should be performed quickly to avoid loses.  Unattended sample injections occurring over-night could make the difference in completing the analysis during the acceptable holding period.   Automated GC sample injection can also improve reproducibility by eliminating the possibility of sample loss due to leaky injection port septa.

7032A-LB Tedlar® Bag Autosampler
The 7032A-LB Autosampler automates the introduction of up to 21 samples into a gas chromatograph for quantitative analysis.  A fixed volume loop is used to measure and equilibrate sample volumes to atmospheric pressure before injection into the GC.  A vacuum pump draws a sample from each bag while keeping the sample loop at atmospheric pressure.  The ability to maintain consistent pressures, temperatures, and loop volumes during the injection makes the 7032A-LB Autosampler a highly reproducible analytical tool for analyzing bag samples.

Variable Volume Injections

The 7032A-LB used an electronic splitter to adjust the actual volume of the sample delivered to a GC.  Using a single loop, the volume can be split as much as 100:1 allowing a greater range of sample concentrations to be analyzed without dilution.   Variable injection volumes also allow calibration curves to be generated from a single calibrated standard cylinder.  Internal standards can be added independent of samples or analytical standards, providing added QA to the analysis.

Tool Free Sample Connection
The 7032A-LB uses black anodized torque wheels attached to each fitting to allow finger tightening of the bags during autosampler loading and unloading.  This improves laboratory efficiency and increases sample throughput.  Teflon reducing ferrules (1/4" to 3/16") provide a reliable seal and are heavy duty enough to use over and over.  Direct connections can be made to both metal and plastic Tedlar® bag valves as supplied by ESS and SKC.

Large Volume Preconcentration

The 7032A-LB is also available without a loop injection valve (Model 7032A-B) for operation with the 7100A Preconcentrator. Instead of being limited to a maximum of 5cc, the 7100A/7032A-B Preconcentration System allows analysis of 10-1000cc. This greatly enhances detection limits, allowing the analysis of compounds in the 1-1000 ppb range.

Focusing option
In order to maintain narrow peak width and maximum sensitivity when performing capillary GC analysis, it may be necessary to focus the sample at the head of the column to eliminate band broadening of the more volatile compounds.  The 7032-02 focusing option is capable of cooling to -190†C using liquid nitrogen during each injection cycle.  Heating of the focuser upon injections can approach 10,000 deg/min, giving extremely fast release of the sample to a capillary gas chromatograph.

System Back-flushing
The 7032A-LB utilizes fused silica lined tubing to reduce transfer losses and retention of contaminants.  To further reduce carryover, each sample inlet can be back-flushed with nitrogen for a user selected period of time before loading the autosampler with the next set of bags.  This virtually eliminates the possibility for system memory effects.