Vapor Generation VG-ICP-AES

1. Vapor Generation (VG)-ICP-AES The Multimode Sample Introduction System An Introduction

2. VG-ICP-AES Combination of Advantages! Dual Mode Benefits Recognized Simultaneous Vapour Generation and Nebulization 1981 – Tandem Nebulizer (Wolnik et al) 1987 – “Smoking Pipe” – Elevated Drain Systems (Benli & Zhuoyong) 1991 – Manifold (Fengzhou et al) New System – Multimode Sample Introduction System (MSIS™) Other Designs Offer Multimode Operation Unique JY design – same principle as “smoking Pipe” based on an elevated drain systemJY design – same principle as “smoking Pipe” based on an elevated drain system

3. MSIS™ An Early Prototype on the Optima 4300An Early Prototype on the Optima 4300

4. MSIS™ An Efficient Cyclonic Spray Chamber Same sensitivity and DL’s as a comparable non-baffled cyclonic spray chamber Reduced condensation in the injector Similar to a baffled SC – without the reduced sensitivity An Efficient Gas/Liquid Separator Slightly better sensitivity than a frit based GLS Dramatically reduced noise Vapour Generation close to excitation source Frit based GLS was a previous best design – now sitting on a shelf collecting dust Frit based GLS was a previous best design – now sitting on a shelf collecting dust

5. MSIS™ Both! Separate or Simultaneous Operation Permits both vapour generation and nebulization without swapping equipment Very little down time between modes Simply open/close different pump channels

6. Technological Advantages Exclusive non-confined point gap mixing Reduces noise Optimal location Thin flowing film exchange Uniform Permits VG for difficult matrices i.e. 10% CaCO3 Rapid Washout Minimal “Cross-Talk”

7. Using the MSIS™ Health and Safety Modes: Operational Parameters Some Recipes

8. So You Want To Do VG: Some Preliminary ConsiderationsHealth & Safety Working With Strong Acids & Bases Powerful Reducing Agent Wear Your PPE’s and Follow Laboratory Safety Procedures Forming Volatile Species that are highly Toxic (i.e. SeH2) and Highly Flammable Gases (H2) Proper Ventilation is Necessary

9. MSIS™ - Modes

10. Nebulization Mode: Recommended Parameters Top and Bottom VG lines should be blocked off Option 1: Pump channels open, ends immersed in beaker of DI water Option 2: Mechanically plugged Ie. Plastic rod, parafilm etc. Nebulizer Uptake Rate (MiraMist™) 1 – 1.5 mL per minute Black/Black Tubing, 20-30 rpm Nebulizer Argon Flow 0.70 – 0.80 (Should be optimized for each instrument)

11. Nebulization Mode: Recommended Parameters Con’t Drain – Always Visually Ensure Adequate Drainage Prior to Use! Minimum Red/Red @ same pump speed as uptake line For Nebulization Mode Only! Or …Maintain same pump tubing as for Vapour Generation or Dual Mode (see next slides)

12. MSIS™ - Modes

13. VG Mode: Recommended Parameters 3 Channel Pump Required Nebulizer Sample Uptake Line – Blocked (Only necessary for self-aspirating nebulizers) Nebulizer Ar Flow Rate Normal Bore injector 0.45 – 0.80 L•min-1 Optimal value is element specific Small Bore injector 0.25 L•min-1 All elements Sample to upper or lower line (We use the lower line to conical reaction tube) 1.0 – 1.5 mL•min-1

14. VG Mode: Recommended Parameters Continued Reductant to opposite line Normally same flow rate as for the sample Drain – Always Visually Ensure Adequate Drainage Prior to Use! We use Black/White or other large bore pump tubing (3.17 mm i.d.)

15. Using Nebulization and VG Mode: A Suggestion for Routine Operation Use of a 2-way (or 3-way) valve for convenience Divert sample to nebulizer or to VG line Automatic line blocking Open/Close pump channel for reductant line

16. VG Mode: Recipes Low Acid Group: As, Sb, Bi, Ge, Sn Low acid concentrations are beneficial! 1% (v/v) HCl or HNO3 Pre-Reduction Using L-Cysteine (As, Sb) Superior to KI or KI/ascorbic acid As (V) ? As (III) Sb (V) ? Sb (III) Reduction of higher oxidation states kinetically slower 1% (w/v) Let sit for ~1 hour

17. VG Mode: Recipes High Acid Group: Se, Te Pre-reduced using HCl + Heat Se (VI) ? Se (IV) Te (VI) ? Te (IV) Higher oxidation states are not reduced to the volatile hydride using NaBH4 4.2 M HCl (35% v/v) common 1.8 M HCl (15% v/v) might be sufficient

18. VG Mode: Recipes Reductant Solution – NaBH4 (KBH4) For Hydride Work 1.0 – 1.5% (w/v) Stabilized Using NaOH Concentration is an important parameter! 0.05 – 0.5% (w/v) We use 0.1% (w/v) Bubble Formation = BAD! Significant Source of Signal Noise Working on a Solution

19. Signal Response to Bubble Formation in Reductant Line

20. Bonus Element: Lead A Low Acid Element 1% (v/v) HCl or HNO3 PbH4: Doubtful existence, but great results 100 ppt…no problemo! Need to add K3Fe(CN)6 1% (m/v) Sample or Reductant? Oxidant or complexing agent? Metastable lead species

21. MSIS™ - Modes

22. Dual Mode: Recommended Parameters 4 Channel Pump – Straightforward 3 Channel Pump? – Possible Larger bore tubing for sample Split sample line after pump using a “T” or “Y” fitting For a self-aspirating nebulizer a proper flow splitter would be required Use of a 3-way Valve Easy switching between 3 Modes

23. Dual Mode: Recommended Parameters Continued Sample to Neb, Sample to VG, and Reductant to VG - Flows: All 1.0 mL•min-1 Successful up to 1.3 mL•min-1 Drainage issues above this value Drain – Always Visually Ensure Adequate Drainage Prior to Use! We use Black/White or other large bore pump tubing (3.17 mm i.d.)

24. Dual Mode Limitations Cannot Determine Boron and Sodium Calcium and Magnesium are questionable Often added to NaBH4 as Sulfate salts Option – Use High Purity (Crystal Form) NaBH4 Oxidation State Control Nebulization of a solution containing 1% L-cysteine? Overall DL’s Reduced Compared to Single Mode Slight to moderate overall

25. Appendix 1 Performance of the MSIS™ Some Non-Traditional Elements Mini MSIS™ Speciation Possibilities

26. ICP Sample IntroductionCyclonic Spray Chamber Advantage(Optima 4300DV) Practical gains in terms of detection limits are slightly less, but still better using the MSIS in nebulization mode. Note: City of Toronto Lab using a 4300 has gained a 3.5 x – 5 x factor for all elements by switching from the x-flow/scott.Practical gains in terms of detection limits are slightly less, but still better using the MSIS in nebulization mode. Note: City of Toronto Lab using a 4300 has gained a 3.5 x – 5 x factor for all elements by switching from the x-flow/scott.

27. Condensation in the Injector BaseOptima 3300 DV Meinhard Nebulizer 1.0 mL/min Sample Uptake, 0.70 L/min Ar

29. Vapour Generation ModeEfficiency! Transport efficiency considerations would only yield at best a factor of 40 – 50 Fact that the atomization/excitation source energy is not required to desolvate accounts for the rest (more energy available to excite the analyte, longer residence time as free atoms is also probableTransport efficiency considerations would only yield at best a factor of 40 – 50 Fact that the atomization/excitation source energy is not required to desolvate accounts for the rest (more energy available to excite the analyte, longer residence time as free atoms is also probable

30. Vapour Generation ModeSensitivity Gain

31. Vapour Generation ModeStability Tests – 10 ppb Std’s RSD’s of Less than 1.7 % for all elements over the three hour period RSD’s of Less than 1.7 % for all elements over the three hour period

32. Results for “Non-Traditional” Elements by VG

33. Results for “Non-Traditional” Elements by VG