GC Cryo-Trap™ (Catalog D3)

D3

GC Cryo-Trap™

FAX: 908-806-6631

www.sisweb.com

Headspace GC Analysis:

L

ow boiling point volatiles from headspace samplers can

be trapped in the GC Cryo-Trap for subsequent analysis.

This will permit the analysis of large gas volume

injections (0.5 to 100 ml or more) as well as multiple injections of

headspace volumes into capillary GC columns.

After trapping

volatile organics at temperatures down to -180°C, the GC Cryo-

Trap is rapidly heated to temperatures up to 400°C to release the

volatiles for separation on the capillary column.

The resulting

peaks are highly resolved, even for the very light volatiles such as

butane and acetone.

In Figure #1, 0.5 µl of gasoline was dissolved in 5.0 ml of water

in a headspace vial.

The sample was heated to 70°C in a CTC

Headspace Sampler and then 1.0 ml of the headspace gas was

injected over a 35 second time interval into the GC injection port

and cryo-trapped in a narrow band on a 1.5µ film thickness guard

column in the GC Cryo-Trap at a temperature of -120°C.

The

sample was trapped for 5.0 minutes and then rapidly heated to

200°C to release the volatiles for GC analysis.

More than 100

compounds were detected and identified including the low boiling

volatiles butane and

pentane.

A lower trapping temperature of

-180°C was able to trap ethane and propane.

Applications of this

technique could easily be expanded to the detection of low boiling

volatiles in water, soil, food products, commercial products and

other solid, liquid and gas matrix samples.

Purge and Trap Applications:

In the thermal desorption technique, large volume gas samples

are typically purged from the sample or adsorbent resin, into the

GC injection port for analysis. Utilizing the GC Cryo-Trap, the

volatile organics from this large gas volume can be cryo-trapped or

cryo-focused in a narrow plug in the guard column in the

GC Cryo Trap.

In Figure #2, 200 milligram of black tea in water at 80°C was

purged with 450 ml of gas and the volatiles trapped on a Tenax TA

desorption trap.

The volatiles on the adsorbent resin were then

thermally desorbed off the resin at a temperature of 250°C utilizing

the SIS Short Path Thermal Desorption System, purged into the GC

injection port and cryo-trapped on a 5.0µ film thickness guard col-

umn in the GC Cryo-Trap at two different temperatures (0° and -

70°C).

The GC Cryo-Trap was then heated to 220°C to release the

trapped volatiles for subsequent GC/MS analysis. At a cryo-trap-

ping temperature of 0°C, volatiles down to methyl isobutyl ketone

were trapped.

At a trapping temperature of -70°C, eight additional

volatiles including acetone were trapped and identified.

Direct Injection Applications:

In Figure #3, a series of neat hydrocarbons from ethane

through nonane were direct injected into the GC injection port uti-

lizing the split mode and trapped on a 1.5µ film thickness guard col-

umn in the GC Cryo-Trap at a variety of temperatures.

This chart

demonstrates the range of volatiles that can be trapped as a func-

tion of the GC Cryo-Trap temperature.

Utilizing the Model 971 with

liquid CO

2

(minimum temperature -70°C), volatiles down to pentane

can be cryo-trapped.

Utilizing the new Model 981 GC Cryo-Trap

which uses liquid nitrogen for cooling to a minimum temperature of

-180°C permits the trapping of ethane on this guard column.

Figure 1

Headspace analysis of gasoline in water using

GC Cryo-Trap

Figure 2

Purge and trap of black tea, then thermal desorb into

GC-Cryo-Trap

Figure 3

Trapping Efficiency of Hydrocarbons on 0.53mm DB-5

(1.5µ) trapped at various GC Cryo-Trap temperatures

Applications of the GC Cryo-Trap and Micro Cryo-Trap™