Needles for Desorption Tubes  TD1, TD2, TD3, TD4, TD5 & AutoDesorb

Description

This 2 piece needle has been specifically designed for the AutoDesorb™ system and is now used for all models of the Thermal Desorption System replacing the previous design. The new design will permit the sealing of the needles and connecting tube to the desorption tube with just a finger tight twist connection. Vespel™ seals (sold separately) are used to make the leak tight seal. Double seals are not needed with this system. The needles are of the side port design to eliminate coring of the GC septa and are 35 mm long. The needles are available in plain stainless steel and now also in Silco™ coated steel to eliminate any metal surface in contact with your samples. These needles and seals can also be used in the Older models of the Thermal Desorption system (Models TD3 and TD-4) as well as the most current version, TD5.

In the AutoDesorb™ System, the needle serves as the transfer line for the introduction of the sample into the Gas Chromatograph. This “short path” for sample transmission is the key advantage of the Short Path Thermal Desorption technology which minimizes sample decomposition, eliminates system contamination and provides for the maximum delivery of samples to the GC.

Options

Selection of Needles for Thermal Desorption

Needles for Desorption Tubes are available in a wide variety of sizes and shapes. Needles are permanently silver soldered to stainless steel caps to provide for a strong leak-free needle assembly. These needle assemblies screw onto the ends of the Desorption Tubes using one of the various types of seals available to provide a leak-tight connection between the needle assembly and the Desorption Tube. Depending on the application and on the type of injection system of the GC, a suitable length of needle will need to be utilized. Needle lengths between 25 mm and 60 mm are available. The shorter the needle, the longer the expected life of the needle. Longer needle lengths are more susceptible to needle bending on injection. However needle bending is minimal due to the autoinjecting system. Three styles of needles are available to suit the users needs, including a special needle for the Jade injection system.

The side hole needle is the recommended needle for use with the desorption system on GC's with septa. The side hole needles, although more expensive, minimize septa coring but still provide good penetration of septa. The 20¡ point needle is the standard needle for general gas chromatography with septum type injectors. It provides excellent septa penetration, however, it can be susceptible to septa coring, and it is therefore necessary to frequently inspect the needle for plugging. When using the Jade injection system it is necessary to use the Jade point needles. Other dome tip type needles will not work with this injector. The Jade needles have a precision angled dome end to smoothly pass through the injector. The optimum needle will vary with injection system, application and septa type and must be determined by the user. Some of the needles listed have smaller inside diameters, which will result in lower gas flow rates through the needle. This may prove to be a disadvantage when using systems requiring higher flows such as in capillary split modes of operation.

If the needle type required is not listed, other needle types and sizes are available on special order from Scientific Instrument Services.

*Jade Point needles are special order. Delivery 8 weeks.