GC/MS Jet for Macrobore GC (With Interchangeable Jets)

The very nature of the modern generation of benchtop mass spectrometer detectors limits the volume of gas that may be introduced into the system. Carrier gas amounts greater than 1 - 2 ml/min cannot easily be pumped from the limited volumes in the system efficiently. Larger capacity pumping systems can be installed but they do not satisfactorily overcome this difficulty.

This is one of the factors that has prevented the large inside diameter capillary columns (0.53mm) from being connected directly into such systems, as these columns are often required to be operated at flows from 3 ml/min to 30 ml/min. It is possible to split the flow from the capillary column using an open split interface but clearly the loss in sample is accompanied by a loss in sensitivity of the analysis.

Difficulties are also associated with interfacing large inside diameter capillary columns to mass spectrometers due to vacuum being applied directly to the end of the capillary column. On 0.53mm I.D. capillary columns the chromatographic separation would be occurring at subatmospheric pressure conditions which presents a number of problems particularly with carrier gas control and some capillary sample introduction systems.

The newly designed jet separator (MJSC) is constructed of metal with a system of glass jets. The design allows the inlet and collector jets to be removed and changed for another set with different dimensions to suit the particular carrier gas and the flow conditions being used. Several aspects of the design ensure that the jets are always aligned perfectly and the critical spacing between the jets is always exactly correct. Disassembling the system does not require special tools or special care in getting the configuration optimized when it is reassembled. Cleaning of the jets is now a simple operation not involving the risk of breaking the separator. The MJSC design is considerably smaller and uses a smaller interface oven.

The MJSC jet separator allows 0.53mm I.D. GC capillary columns to be used with Mass Selective Detectors with improved sensitivity over open split interface systems.

High Yield

The table below shows the yields achieved for a series of low molecular compounds. Low molecular components are considered to be more difficult components to achieve high yield values. Components with higher molecular weight would in general terms be expected to give higher yields but across this range no significant discriminatory trend was observed.

                                    Yield
Component               Helium Carrier        Hydrogen Carrier
1,2 dichloropropane          25%                    72%
chlorobenzene                28%                    68%
tetrachloroethane            38%                    74%
o-dichlorobenzene            34%                    70%
 

The achievable yield is clearly superior with hydrogen. Hydrogen is clearly the preferred carrier gas in terms of capillary column performance and efficiency of the separator, however, safety aspects in using hydrogen need to be considered.

Installation

To facilitate the installation directly into a GC/MSD system, heated ovens for the jet separator have been designed. These ovens are designed to utilize the heater cartridge, thermal sensor and temperature control circuit of the GC.

A special jet separator oven has been designed specifically for HP5890 gas chromatographs. Other designs are also available that can be fitted to other common gas chromatographs.

Transfer of the sample from the jet separator to the MSD is via either a length of 0.53mm I.D. fused silica or glass lined stainless steel tubing.

Interchangeable Jets and Fittings

The unique flexibility of the MJSC is derived from its interchangeable jets and fittings. Jets can be easily maintained, cleaned or replaced while maintaining perfect alignment. A range of fittings are available for connection of the MJSC to GC configurations.

Oven Configurations

SGE has available a range of MJSC heater block (ovens) configurations to suit most GC makes and models. These blocks are designed to utilize the existing heater cartridge and temperature sensors fitted to most instrument detector or injector housings. If your GC/MS system does not have a heated interface, a cartridge heater/sensor asssembly is available, see below.

Analysis of Purgeable Hydrocarbons

This is a total ion chromatogram of a range of Purgeable Halocarbons. Using the MJSC, even very volatile compounds like methylene chloride can easily be analyzed. Excellent yield was obtained for this group of compounds.

Ordering Information

Two, complete MJSC Molecular Jet Separators/Oven assemblies fitted with 15ml/min (He) jets, are available. One specific for the HP5890, and the other, a general MJSC/oven assembly suitable for most other GC/MS combinations. The ovens are designed to utilize the existing heater cartridge fitted to the instrument. Optional Jet configurations are also available to suit specific operational conditions.

Complete Macrobore Jet Separator Kit

For GC/MS instruments such as the HP5971 which do not currently have a jet separator, a complete kit is available. There are two different kits available. The 113612K is specifically designed for addition to an HP MSD system and mounts easily to the 5890 GC. Note: If your MSD already has a jet separator, then you only need the jet separator (113612) not a complete kit. The 113614K is a general kit for use in other GC/MS instruments, where a jet separator was not previously installed. These kits come complete with a jet separator, vaccum pump, hose and fittings, and the heater and temperature sensor. The vaccum pump included with the kit is an Alcatel model UM2005. See the vacuum section of this catalog for complete details and specifications of the vaccum pump. The heater/sensor assembly is complete with connections to hook up to the HP 5890 GC, or the SIS temperature controller for the 113614K.

Part No.	Description	UOM	est wt.	Quantity In Stock	Price	Quantity to order
113612	(Order Code: MJSC-HP5890) Complete Jet Separator/Oven Assembly for HP5890 supplied with 15ml/min He Jets*	EA	0.25	0(#)	---	---
113614	(Order Code: MJSC/GMO) Complete Jet Separator with General Oven Assembly (supplied with 15ml/min He Jet) GC make and model should be specified when ordering.**	EA	3	0(#)	---	---
113612K	Complete Jet Separator Kit for HP5890.Includes: 113612 Jet Separator, HPH2 Heater/Sensor Assembly, UM2005 Alcatel Vac. Pump, RF075-Six feet of Vac Hose, 3/4in, NS25075 Hose fitting, HSS012 Hose Clamp	EA	55	0(#)	---	---
113614K	Complete Jet Separator Kit for HP5890.Includes: 113614 Jet Separator, UM2005 Alcatel Vac. Pump, RF075-Six feet of Vac Hose, 3/4in, NS25075 Hose fitting	EA	55	0(#)	---	---
HSS012	Stainless Steel Worm Gear Clamps, 9/16 in to 1 1/4 in, pkg of 10	PK	0.5	7	$11.50	1
113600		---		0(#)	CALL	1
113604	(Order Code: MIJ/15-He) Replaceable Jet for flow of 15ml/min He(nom)	EA	0.25	0(#)	CALL	1
113608	(Order Code: MIJ/30-HE) Replaceable Jet for flow of 30ml/min He(nom)	EA	0.25	0(#)	---	---
1136122	Frit for Jet, reduces clogging	EA	0.5	0(#)	---	---
(#) Standard lead-time for out-of-stock items is approximately two weeks.
Ordering information. International (non-US) prices available through your local dealer.

* 113612: The SGE heater block is designed to use the existing heater cartridge fitted to the instrument.

** 113614: Note: MJSCs for GC makes and models other than the HP5890 are available on request.

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