PFA Inert Kit Technical Features
Savillex’s superior molding and secondary finishing capabilities have enabled the design of PFA inert kits with the long term stability and reliability of a traditional quartz spray chamber. Until now, the performance of inert spray chambers has been compromised by limitations in molding and manufacturing capabilities. Savillex set out to eliminate these compromises. The kits comprise of a PFA Scott-type spray chamber, PFA connecting tube and PFA injector assembly, fitted to a semi-demountable quartz torch. The spray chamber is 35mm outer diameter with a PFA inner tube held precisely in position by fins at top and bottom. Unlike single pass PFA spray chambers, the spray chamber is a true double pass design, which reduces signal fluctuations, improves RSDs and lowers detection limits. The double pass design also removes all sample aerosol droplets greater than 10uM diameter. Removing larger droplets is key to preventing plasma overloading, increasing plasma robustness and reducing oxide levels. While PFA kits have traditionally been used for semicon applications, the Savillex kits can be applied equally to non-semicon high matrix sample types.
The shape and position of the inner tube at the bottom edge has been optimized to ensure a smooth drainage of droplets into the drain fitting positioned below. The design of the drain fitting prevents build up of liquid, which would lead to signal fluctuation. The end cap is O-ring free and features a 6mm port for a C-Flow nebulizer, and a make up gas port. Schematic diagrams of the available inert kits are shown below.
Schematic diagram - PFA inert kit
An important contributor to the performance of the kit is the connector design. In order to eliminate droplet build up, in this area, careful attention has been paid to the design of the aerosol flow path. The chamber side arm has a wide inner diameter (ID), tapering to the connector. The connector fitting is O-ring free and push fit, and the ID matches precisely the ID of the side arm and of the torch injector holder on the exit side. Because the aerosol flow path is perfectly smooth with no ledges or steps, droplet formation is eliminated (see diagram) and washout is improved.
Close up of connector (light blue) showing smooth flow path
The semi demountable quartz torch fits onto the injector holder with an O-ring seal, which gives a more secure and easier to remove connection than O-ring free torch mounts. Since no sample liquid comes into the contact with the torch O-ring, there is no risk of increased background contribution. Injectors are available in either sapphire or platinum. In the Agilent versions, an optional gas port for O2 addition on the injector holder is available for the 7500 Series. For the Agilent 7700/8800 Series, the connector has a gas port that allows for O2 addition and for operation in HMI mode. All parts that come into contact with the sample come precleaned in high purity HNO3/HF, ready for immediate use. Choose one of the kits on the ordering information page and add one of the Savillex nebulizers to make a complete inert sample introduction system.