Using the Aridus 3 Desolvating Nebulizer System in Geochemistry
Liquid Sample Introduction Desolvating Pneumatic Nebulizer System • Combine a low-flow inert pneumatic nebulizer with a heated PFA spray chamber and fluoropolymer membrane desolvator for liquid sample introduction to an ICP-MS instrument.
Liquid Sample Introduction Desolvating Pneumatic Nebulizer System Benefits • – Introduction of corrosive liquid samples that may contain hydrofluoric acid (no silicon-containing wetted parts) – Introduction of low volume (< 1mL volume) liquid samples – Analyte ICP-MS signal enhancement – Reduction of solvent-based mass spectral interferences (ex. hydrides, oxides)
Desolvating Pneumatic Nebulizer System Applications • Geochemistry – U-series dating studies (geochronology) – Ca, Fe, Hf, Mg, Nd, Ni, Pb, S, Si, Sr isotope measurements • Semiconductor – High-purity acids (ex. HNO 3 , HCl) and solvents (ex. isopropanol) • Pharmaceutical – Samples dissolved in DMF (dimethylformamide) • Clinical – U and Pu in urine
Aridus3 Desolvating Nebulizer System Front View Dimensions: 33.7 cm W x 19.2 cm H x 52.0 cm D
Teledyne CETAC Aridus3 Schematic Gas Flow Outline
Aridus3 Desolvating Nebulizer System Block Diagram
Desolvating Pneumatic Nebulizer System Operational Characteristics • Heated PFA Spray Chamber and Heated Membrane Desolvator – Maintain nebulized liquid sample in vapor phase • Argon Sweep Gas Flow – Establish humidity gradient across membrane to remove sample solvent vapor • Nitrogen Addition Gas – Introduced after membrane desolvator; low-flow N 2 addition to the dry sample gas stream may enable better energy coupling between the induction region of the ICP-MS plasma and the central channel of the plasma.
Desolvating Pneumatic Nebulizer System Operational Characteristics • Argon Sweep Gas Supply – May be from a separate Ar source or teed from main Ar supply for the host ICP-MS • Nitrogen Addition Gas Supply – N 2 source (ex. compressed cylinder) should be 99.995% or better
Desolvating Pneumatic Nebulizer System Operational Characteristics • Nitrogen Addition Gas – Can cause mass spectral interferences • Examples: 40 Ar 14 N + on 54 Fe + and 54 Cr + , 40 Ar 14 N 2 + on 68 Zn + – N 2 gas flow can be reduced or replaced with low flow of Ar
Desolvating Pneumatic Nebulizer System Reference for N 2 Addition 1. G.L Scheffler and D. Pozebon, Advantages, drawbacks, and applications of mixed Ar-N 2 sources in inductively coupled plasma – based techniques: an overview, Anal. Methods, 2014, 6, 6170-6182.
Aridus3 Desolvating Nebulizer System CFlow PFA Nebulizers Neb gas supply port for 4mm tubing Encapsulated carbon-fiber support Uptake rates (self-aspiration) of 50,100 or 200 microliters/min
Aridus3 Desolvating Nebulizer System CFlow Nebulizer w. PFA Spray Chamber Spray Chamber Drain Line Port accepts standard 6mm diameter nebulizers
Aridus3 Desolvating Nebulizer System Connections for Power, Communications, Gas Flows, Sample Out, Ar Sweep Gas Out
Aridus3 Desolvating Nebulizer System w. Nu Instruments MC-ICP-MS Aridus3 AridusII
Aridus3 Desolvating Nebulizer System w. ThermoFisher Neptune MC-ICP-MS
Aridus3 Desolvating Nebulizer System 4-Liter Trap Bottle (Ar Sweep Gas Out) Insulated Sweep Gas Out Line Vent Out Line 4-Liter Trap Bottle
Aridus3 Desolvating Nebulizer System AridusLink Software
Desolvating Pneumatic Nebulizer System Suggested Tuning Steps (1) – Aridus3 w. ICP-MS 1. Set the Ar sweep gas flow to 1.00 L/min and the N 2 addition gas flow to 0.5 mL/min or less before starting the ICP-MS plasma. 2. Start the ICP-MS plasma and set the PFA nebulizer gas flow to 1.00 L/min. 3. Introduce a tuning solution (ex. 1ppb) containing elements such as Co, Y, In, Ce, Pb, U to the PFA nebulizer. 4. Increase the Ar sweep gas flow until the Ce signal stops increasing and the % CeO/Ce begins to go over 1.0% A typical range may be 3.00 to 6.00 L/min Ar. 5. Introduce the N 2 addition gas; a typical flow range may be 3.0 mL/min to 6. 10.0 mL/min. Add the N 2 until the tune element(s) signal begins to level off or significantly decreases.
Desolvating Pneumatic Nebulizer System Suggested Tuning Steps (2) – Aridus3 w. ICP-MS 6. Adjust the Ar sweep gas flow (usually downward) until the %CeO/Ce ratio is ~0.1% or less. Often the analyte signal (ex. In, Ce) will increase after the Ar sweep gas is adjusted. 7. Adjust the PFA nebulizer gas flow for highest signal and lowest %CeO/Ce. 8. Optimize the ICP-MS torch xyz sampling position for the highest analyte signal. 9. Optimize the ICP-MS ion optics for the highest analyte signal. 10. The Ar sweep gas and N 2 addition gas may be fine tuned for best signal and lowest oxides; the %CeO/Ce will typically be 0.05% or less.
Aridus3 Desolvating Nebulizer System Tune Signal Profile w. MC-ICP-MS 235 U signal in red. Variable Ar sweep gas flows (L/min); N 2 set at 3.9 mL/min 4.00 4.25 3.50 4.50 3.00 Tuning profile during introduction of enriched solution of 235 U at concentration of 0.11 picomole/mL. Maximum 235 U signal is ~ 250,000 cps or ~ 5.0 mV.
Aridus3 Desolvating Nebulizer System Tune Signal Profile (1) w. Quad ICP-MS 3.00 Vary Ar Sweep Gas flow (L/min) Neb gas set at 1.0 L/min 3.50 N 2 set at 0.5 mL/min 2.50 2.00 1.50 1.00 1ppb In and Ce; 1.0s int. time
Aridus3 Desolvating Nebulizer System Tune Signal Profile (2) with Quad ICP-MS Set neb gas at 0.90 L/min 3.00 2.90 2.80 3.00 3.25 3.50 Add 6.0 mL/min N 2 1ppb In and Ce; 1.0s int. time
Aridus3 Desolvating Nebulizer System Tune Signal Profile (3) w. Quad ICP-MS Neb Gas 0.90 L/min Ar Sweep Gas 2.80 L/min N 2 gas 6.0 mL/min 1ppb In and Ce; 1.0s int. time Full tune of xyz torch position & ion optics
Sample Preparation - Geology Outline for Speleothems and U-Series Dating • Sample powder masses generally from 20 to 100 mg • Sample powders dissolved in 15N HNO 3 and spiked with a mixed 229 Th- 233 U- 236 U solution. • Subsamples dried and re-dissolved in 7N HNO 3 • Subsamples added to anionic resin columns to separate the U and Th • Spiked aliquots of U and Th in 3% HNO 3 are then analyzed using MC-ICP-MS Speleothems: cave deposits U-Series Dating: based on ratio of 234 U to 230 Th in a sample, with the 230 Th a decay product of 234 U
Sample Preparation - Geology Reference Cheng, H., Edwards, R.L., Shen, C.-C., Polyak, V.J., Asmerom, Y., Woodhead J., Hellstrom, J., Wang, Y., Kong, X., and Spötl, C., Improvements in 230 Th dating, 230 Th and 234 U half-life values, and U-Th isotopic measurements by multi-collector inductively coupled plasma mass spectrometry, Earth and Planetary Science Letters, v. 371, p.82-91, 2013.
Sample Types Stalagmite Sample BC9-88mm was drilled to screen this sample for its age. 9 cm 8 cycles were run per block with an integration time of 20 seconds per cycle. Stalagmite BC9, Carlsbad Cavern, New Mexico USA Sample collected by V. Polyak by federal permit granted by Carlsbad Cavern National Park.
Sample Types Stalagmite BC9 Carlsbad Cavern, New Mexico USA 130 mg calcite powder 238 U = 0.5205 ± 0.0005 ppm 232 Th = 0.00320 ± 0.00004 ppm 230 Th/ 232 Th = 18.6 ± 0.3 230 Th/ 238 U = 0.0374 ± 0.0003 δ 234 U measured = 1554 ± 3 ‰ δ 234 U initial = 1561 ± 3 ‰ Age uncorrected = 1608 ± 14 yr B2k Age corrected = 1210 ± 120 yr B2k δ = activity ratio Yr BP = years before 2000CE
Sample Types Moonmilk – Grand Canyon, Arizona USA Moonmilk is a cave deposit (speleothem) that has a toothpaste-like consistency. Mineral is calcite.
Sample Types Moonmilk – Grand Canyon, Arizona USA sample powder size = 50 mg 238 U concentration (ppm) = 0.6610 ± 0.0005 232 Th concentration (ppb) = 11.24 ± 0.05 230 Th/ 232 Th activity = 4.0 ± 0.1 230 Th/ 238 U activity = 0.02209 ± 0.00083 δ 234 U measured = 297 ± 1 ‰ δ 234 U initial = 299 ± 1 ‰ uncorrected age = 1871 ± 71 yr BP corrected age = 1492 ± 202 yr BP
Sample Types Altered Stalagmite Hidden Cave, Guadalupe Mountains, NM USA Testing age of altered layers, age corrected 22,959 +/- 1498 BP 50 mm
Sample Types Old Stalagmite (cross-section) Fort Stanton Cave, Central NM USA 100 mm stalactite straw 443,587 ± 10,204 BP Age corrected
Aridus3 Desolvating Pneumatic Nebulizer System in Geochemistry Using the Aridus3 with a CFlow-100 PFA nebulizer enhances analyte signal by a factor of 4 to 5 making analyses easier and faster. Smaller masses of often limited (and expensive to obtain) samples can be analyzed, which can also reduce sample column chemistry time. Note that the Neptune MC-ICP-MS was equipped with Jet sample and X interface skimmer cones but not with the high performance interface vacuum pump.
Acknowledgement • We would like to thank Dr. Yemane Asmerom and Dr. Victor Polyak of the University of New Mexico Department of Earth and Planetary Sciences for their assistance with tests of the Teledyne CETAC Aridus3 unit with the Thermo Neptune MC-ICP-MS.
Automated Sample Introduction with the Aridus3 ASX-112FR Autosampler
Automated Sample Introduction ASX-112FR Autosampler Sample Tray 24 position central rack 1.5 mL PFA vials
Automated Sample Introduction ASX-112FR Autosampler Sample Racks 42 position, 7 mL PP vials 30 position, 14 mL PP vials
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