Thermal Desorption Sample Collection System (Catalog C20)

Thermal Desorption Sample Collection System

C20

Phone: 908-788-5550

www.sisweb.com

T

his Sample Collection System permits the purging of

volatiles and semi-volatile components present in solid

materials and their trapping on Desorption Tubes packed

with an adsorbent resin for subsequent analysis by desorption

utilizing the Short Path™ Thermal Desorption System. Volatiles can

be collected from sample sizes ranging from less than 0.5 gram up

to 20 grams.

This technique for collecting volatiles from samples for

analysis is used:

(1)

To permit the analysis of trace components in larger

sample sizes than could be analyzed by Direct Thermal

Desorption in the Short Path Thermal Desorption System. Soil

samples up to 20 grams can be sampled in the 0.5" diameter

tubes.

(2)

To permit the analysis of volatiles from organic

samples

containing high concentrations of water. Water is not retained by

many adsorbents (such as Tenax™) whereas other organic

volatiles would be trapped by the adsorbents. Water interferes with

the GC analysis by forming plugs to block carrier gas flow thru the

GC columns when the GC oven is maintained at subambient

temperatures during the initial desorption of samples into the GC.

(3)

To permit the analysis of volatiles emitted from the

samples at different temperatures by collecting the volatiles onto

Desorption Tubes at increased temperatures. It is therefore

possible to set up studies to determine the temperatures of

emission of volatiles and semi-volatiles from materials such as

carpet fibers, packaging materials, building products, etc.

Samples to be analyzed are placed inside glass or stainless

steel tubes and held in place by glass wool plugs. The system is

designed to sample from 0.5" diameter glass tubes, and also from

0.25" diameter glass tubes with optional adapters. Sample tubes

are 14.0" long each.

When ready for sample collecting, the long

tube containing the sample is placed in the sample Collection

Oven, fitted at one end with a supply of carrier gas to flush out the

residues, and fitted at the opposite end with a preconditioned

Desorption Tube with adsorbent resin. The Oven is set for the

desired temperature and the desired components are collected

onto the Desorption Tubes. Oven temperatures can range from

room temperature up to 250° C. The temperature used, as well as

the time of sampling, depends on the nature of

the samples being analyzed and the require-

ments of the analyst. Soil samples are typically

analyzed at 80° C and sampled for 30 to 60

minutes.

The Sample Collection System consists of a

sample tube oven with ports for four

0.5" diam-

eter sample tubes. Up to four samples can be

collected simultaneously with the system. Four

rotameters regulate the gas flow thru each of

the samples independently of one another. A

Watlow precision Temperature Controller pro-

vides accurate control of the temperature of the

Sample Collection Oven up to 250° C. A digital

readout indicates the actual oven temperature.

The actual Sample Collection Oven consists of

a large aluminum plate with holes drilled for

the

sample tubes and is heated by cartridge

heaters. Heat transfer to the sample tubes

occurs via direct thermal transfer from the alu-

minum

block

to

the

sample

tubes.

Temperatures can be maintained within 1% of

the full scale reading.

On the front of the Sample Collection System four quick dis-

connect fittings connect to a 1/8” flexible transfer line to provide

gas flow thru each of the sample tubes and Desorption Tubes

during sampling. By providing gas flow from a carrier gas such as

Nitrogen or Helium thru the heated sample tubes and the

Desorption Tubes while sampling, the volatiles and semi-volatiles

will be purged from the sample and will be trapped by the adsor-

bent in the Desorption Tube. A single 1/8” fitting on the back of

the System is provided for the attachment of the gas from its

source.

Sample Collection System for the collection

of thermally sparged volatile samples

Desorption Tube

with Tenax

Desorption Tube

with Tenax

Dry Purge Gas Flow

(optional)

Sample Heater Block

Sample Heater Block

Sample in Glass Tube

Carrier Gas Flow

782071

782072

782075

Carrier Gas Flow

782071

Note: The SIS Sample Collection System can be Modified for other

Manufacturers Desorption Tubes