The CETAC Aridus Desolvating Nebulizer System combines our experience in low flow nebulizers with a highly efficient membrane desolvation system. Features of the Aridus include: - Low-flow Aspire PFA nebulizer(50 or 100 µl/min uptake)
- Aspire PFA nebulizer designed to alleviate nebulizer "vapor lock"
- Membrane desolvation for reduced solvent-based interferences for ICP-MS
- Nitrogen addition for ICP-MS signal enhancement
- Built-in flow control for Ar sweep gas and additional N2 gas
- Special PFA spray chanber for high temperature (110 deg C) operation
- Dedicated heat controllers for flexible temperature setting of spray chamber and membrane desolvation unit
- Pumped spray chamber drain and solvent trap bottle
- All wetted parts mades of inert materials
- Interfaces to all ICP-MS instruments
- Optional CETAC ASX-100 micro-autosampler
Introduction
The Aridus System combines the Aspire PFA nebulizer with a custom-designed heated PFA spray chamber. With a normal sample uptake rate of 100 µl/min, the Aridus can enable the determination of all required elements with < 1 mL of sample. As all wetted parts are made of inert materials, the Aridus allows the introduction of both non-HF-containing and HF-containing samples with a single sample introduction system
The schematic below illustrates the operation of the Aridus System. Sample vapor from the heated PFA spray chamber passes into a heated fluoropolymer membrane. A counter-current flow of argon sweep gas is used to remove solvent vapors that permeate the membrane. A low-flow of nitrogen gas can be added after the membrane to further enhance ICP-MS sensitivity.
Signal Enhancement for ICP-MS
The Aridus can significantly enhance ICP-MS sensitivity, with improvement of up to 10 times or more, depending on the ICP-MS model. The graph below shows Aridus sensitivity enhancement of a factor of 12 to 25 for five typical tuning elements when compared to a conventional higher-flow pneumatic nebulizer (in this example a v-groove type). The Aridus nebulizer used is an Aspire-100 (100 µl/min uptake, self-aspirating).Oxide and Hydride Reduction
The desolvating membrane of the Aridus can signficantly reduce sample solvent loading (ex. H2O) to the ICP-MS. Compared to a conventional pneumatic nebulizer in a chilled spray chamber, the CeO/Ce ration is lowered by a factor of 30 to the very low level of 0.02%. Hydride interferences are also reduced, with the significant example of 238UH+ interference on 239Pu+. The Aridus reduces 238UH+ by approximately 12-fold. (Both experiments performed with Agilent 4500 ICP-MS.)
Long Term Signal Stability
Long-term Aridus signal stability (5 hours) for tuning elements (Li, Y, Ce, Tl) is excellent with the new Aspire-100 PFA nebulizer and PFA spray chamber. %RSDs for 21 individual measurements over this time period for a 1 ug/L solution are: Li 2.1%, Y 1.5%, Ce 1.2%, Tl 1.4%.
Isotope Ratio Measurements
The Aridus system is especially useful for the measurement of isotope ratios by multicollector (MC) ICP-MS. Signal enhancement and signal stability improves ion counting statistics, particularly for low abundance isotopes. The Aridus enahnces MC-ICP-MS sensitivity by up to 5-fold for Th and U, while the membrane desolvator markedly reduces a number of significant hydride interferences on Th and U.
Aridus Standard Components/Options
The CETAC Aridus Sample Introduction System package includes (1) Aspire PFA nebulizer, (1) PFA spray chamber, a rinse kit, a spare parts kit and a one year limited warranty on all components. The CETAC ASX-100 micro-autosampler (option) may be coupled to the Aridus for automated low-volume sample analysis
