Choosing a Nebulizer
THE MEINHARD® CONCENTRIC GLASS NEBULIZER reflects the exacting standards in design and manufacturing that have made it the choice of the industry worldwide. Its advantages include simplicity of design and operation, reproducible and self-aligning aerosol, and close fabrication control. The MEINHARD® nebulizer is used in all major ICP instruments on the market today.
Specifications
Configuration: Concentric, monolithic
Material: Borosilicate glass (TR-series) Quartz (TQ-series)
Tubulation O.D.: Shell, 6mm; fluid inputs, 4mm
Internal liquid volume: ~0.1 mL
Annular separation at nozzle: ~20µm
Annular area: ~0.03mm_
Capillary I.D.: TR-series 0.22 - 0.32mm
Functional criteria:
Pc: Calibration input pressure at rated Ar flow
Ra: Water aspiration at -5cm head, at rated Ar flow
| Pc (psig) |
| Nominal |
Range |
| 20 |
10-24 |
| 30 |
25-40 |
| 50 |
41-60 |
| Ra (mL/min) |
| Nominal |
Range |
| 0.5 |
0.3-0.6 |
| 1 |
0.7-1.4 |
| 2 |
1.5-2.4 |
| 3 |
2.5-3.5 |
MODEL DESIGNATION:
TR-Pc-NRa
Pc: Nominal Pressure (20, 30, 50 psig)
N: Nozzle Type (A, C, K, CK)
Ra: Natural Aspiration Rate at rated Argon flow (0.5, 1, 2, 3 mL/min)
Nozzle Selection Guide:
TYPE A
| Application: |
General Purpose |
| Calibration reference: |
1.0 L/min. Argon |
| End Surfaces: |
lapped |
| Capillary recess, mm: |
0.0 |
| Uptake suction: |
+ |
| Stability of aerosol delivery: |
+ |
TYPE C
| Application: |
High Solids |
| Calibration reference: |
1.0 L/min. Argon |
| End Surfaces: |
vitreous |
| Capillary tip recess, mm: |
~0.5 |
| Uptake suction: |
++ |
| Stability of aerosol delivery: |
++ |
TYPE K
| Application: |
Argon low-flow |
| Calibration reference: |
0.7 L/min. Argon |
| End Surfaces: |
lapped |
| Capillary tip recess, mm: |
~0.5 |
| Uptake suction: |
++ |
| Stability of aerosol delivery: |
++ |
Type CK
| Application: |
Argon low-flow, High Solids |
| Calibration reference: |
0.7 L/min. Argon |
| End Surfaces: |
vitreous |
| Capillary tip recess, mm: |
~0.5 |
| Uptake suction: |
++ |
| Stability of aerosol delivery: |
++ |
OPERATION
The MEINHARD® nebulizer will aspirate liquid sample naturally when the rated flow of gas is directed into the sidearm and a sample feed is connected to the liquid input. All models may be operated with externally pumped analyte provided the sample flow is not significantly below the natural aspiration rate. (The flow can usually be reduced to 1/3 the natural aspiration rate before aerosol instability occurs.) Calibrations reflect a standard operational reference and are not intended as limitations on conditions of use, which can vary widely. Operation can be optimized for specific instruments.
MODIFICATIONS AND SPECIAL APPLICATIONS
A SMALL BORE (SB) modification provides an efficient way to link HPLC to ICP.
This small bore 1/8" O.D. liquid input replaces the standard 4 mm input on the nebulizer, reducing dead volume by approximately 80%. The end of the SB tubing is prepared for a tight, leak-free seal. Internal geometric irregularities are kept to a minimum to preserve peak boundaries. Our chromatographic union Fit Kit #1 is available to aid in connecting to 1/16" column tubing, and a very low dead-volume Fit Kit # 1-M is also available. Order by substituting SB- for TR- in the model designation.
FOR LC-MS
The CIR-50-HK is designed to use 0.7 L/min of helium at 50 psig. A shortened liquid input allows for insertion of a fused silica LC column directly into the capillary of the nebulizer. Dead volume is virtually eliminated and there is no need for connective fittings.
SPECIAL REQUESTS
If you have unique requirements or an unusual application, feel free to contact us. We can manufacture nebulizers with a wide variety of dynamic characteristics and we welcome your inquiries.
MAINTENANCE TIPS
Properly maintained, a MEINHARD® nebulizer should yield long-lasting and trouble-free performance. We offer a set of helpful tips to aid in the routine care of a nebulizer and to provide restorative procedures for inoperative (but undamaged) nebulizers. The tips are available as a courtesy to our customers on this web site or simply contact us to request a free printed copy.
|
THE HIGH EFFICIENCY NEBULIZER (HEN)
is especially suited for microsample analysis in HPLC and FIA. It exhibits detection limits comparable to those of a standard MEINHARD® nebulizer while consuming 25 times less sample
(see table below).
|
|
It is designed to accommodate 1 L/min argon at 170 psig and can function reliably at liquid flow rates from 1 to 1200 µL/min. The HEN fits the same spray chambers as the TR- series nebulizers. A high pressure fitting Fit Kit #2 is recommended for secure attachment of the nebulizer gas tubing. A union Fit Kit #1 is available to provide a minimum dead volume, leak-free connection to a 1/16" sample feed. The Fit Kit #1-Micro uses microbore 0.008" ID Teflon tubing to dramatically reduce dead volume in the sample uptake tubing to the HEN. To order, request model HEN-170-AA.
Representative Detection Limits (µg/L)
| |
Ref. (1) |
TR-30-A2 |
HEN |
| Solution Flow Rate (µL/min): |
1900 |
2000 |
80 |
| Cu |
324.7 |
5.4 |
3 |
3 |
| Ni |
231.6 |
15 |
5 |
5 |
| Pb |
220.3 |
42 |
20 |
20 |
| As |
193.6 |
53 |
30 |
40 |
| Be |
313.0 |
0.3 |
0.2 |
0.2 |
(R. K. Winge, V. A. Fassel, V. J. Peterson, and M. A. Floyd, Inductively Coupled Plasma-Atomic Emission Spectroscopy, An Atlas of Spectral Information, Elsevier, New York (1985))
TR-30-A3 (above) and HEN-170-AA (below) nebulizing ~3000 µL/min and ~50 µL/min, respectively. Full Specifications:(Data cited herein included in a paper by Dr. Hsiaoming Tan delivered at FACSS XIX, September 22, 1992) The High Efficiency Nebulizer (HEN) is suitable for microsample analysis in HPLC and FIA as well as for more routine higher flow analyses, yet preserves the low cost and simplicity of design and operation that characterize the MEINHARD® nebulizer.
The increase in efficiency is accomplished by increasing the kinetic energy of the nebulizing gas and by optimizing the liquid-to-gas mass ratio. These modifications are consistent with the trends predicted by the equation of Nukiyama and Tanasawa and subsequently more fully developed by Barry Sharp (B. L. Sharp, J. Anal. Atomic Spectrom. 3, 613 and 939 (1988)). Table I (below) compares the dynamic characteristics and geometric parameters of the HEN to
those of the standard nebulizers. Table II lists the operating conditions under which the other experimental data reproduced in this article were taken.Table I: Nebulizer Comparison
| Dynamic Characteristics |
| Nebulizer Type |
Operating Pressure (psig) |
Sample Input Rate (mL/min) |
| |
|
Nominal |
Range |
| HEN |
170 |
0.08 |
0.01-1.2 |
| TR-50-C1 |
50 |
1.0 |
0.5-2.5 |
| TR-30-A3 |
30 |
3.0 |
1.0-3.5 |
| Geometric Parameters |
| Nebulizer Type |
Annular Area (mm2) |
Capillary ID (mm) |
Capillary Wall (mm) |
| HEN |
0.0072 |
0.079 |
0.033 |
| TR-3--A3 |
0.034 |
0.34 |
0.046 |
The HEN operated at a sample flow rate of 0.08 mL/min achieves limits of detection comparable to those of a standard concentric nebulizer operated at a sample flow rate of 2.0 mL/min (see Table III). The HEN was tested at sample input rates ranging from 0.01 to 1.2 mL/min (see Figure I). Figures II and III compare the net signal intensities and percent RSD's of the HEN with those of the TR-50-C1 and TR-30-A3 when all three nebulizers are operated at 0.08 mL/min sample flow. The HEN exhibits both higher net signals and lower percent RSD's.
Table II: Operating Conditions
| ICP System |
Spectroflame-ICP D |
|
| |
(Spectro Analytical Instruments, Fichburg, MA) |
|
| |
Forward r.f. Power (W) |
1200 |
| |
Frequency (MHz) |
27 |
| |
Outer gas flow rate (L/min) |
13 |
| |
Intermediate gas flow rate (L/min) |
0.8 |
| |
Injector gas flow reate (L/min) |
1.0 |
| Mass Flow Controller |
Tylan RO-32 (Tylan Corp., Carson, CA) |
|
| Syringe pump |
Model 22 (Havard Apparatus, Inc. South Nick, MA) |
|
| Sample Introduction system |
MEINHARD concentric nebulizer, Scoot double pass spray chamber, standard 20mm torch |
|
There are several other advantages to this high efficiency nebulizer. Washout times for the HEN is about 40 seconds, again quite comparable to that of the standard MEINHARD® nebulizer. No high pressure pumping is needed for sample delivery as is required in some other high pressure, low flow nebulization systems. The sample input tube has a 0.125" outer diameter so that it can be used with standard chromatographic fittings, and a 0.026" inner diameter to minimize dead volume. The end of the input tube is ground flat and fire polished to provide a leak-free seal. Also, the external configuration of the HEN allows for it to be easily interchanged with a standard nebulizer.
Table III: Comparison of Detection Limits (µg/L)
| |
Ref. 1 |
TR-30-A3 |
High Efficiency Nebulizer |
| Rate (µL/min) |
1900 |
2000 |
60 |
80 |
100 |
| Cd 226.5 |
3.4 |
2 |
2 |
2 |
2 |
| Ni 231.6 |
15 |
5 |
7 |
5 |
7 |
| Cu 324.7 |
5.4 |
3 |
3 |
3 |
2 |
| Fe 259.9 |
6.2 |
2 |
4 |
3 |
2 |
| Pb 220.3 |
42 |
20 |
40 |
20 |
30 |
| As 193.6 |
53 |
30 |
50 |
40 |
40 |
| Ba 455.4 |
1.3 |
0.6 |
0.8 |
0.7 |
0.6 |
| Be 313.0 |
0.30 |
0.2 |
0.4 |
0.2 |
0.2 |
| Co 228.6 |
7.0 |
4 |
5 |
3 |
3 |
| Mn 257.6 |
1.4 |
0.5 |
0.9 |
0.6 |
0.5 |
| V 311.0 |
10 |
4 |
4 |
4 |
2 |
THE DIRECT INJECTION HIGH EFFICIENCY NEBULIZER (DIHEN)
(US Patent #6166379)
The DIHEN is a pneumatic micronebulizer designed to introduce micro-volumes of sample solutions directly into an inductively coupled plasma (ICP) or inductively coupled plasma mass spectrometer (ICPMS). The DIHEN-ICPMS approach is particularly well suited for ultratrace isotope and elemental analysis of sample types that are of limited volume, toxic, or expensive, or that exhibit speciation interferences. The DIHEN may be used as a micronebulizer in other atomic spectroscopy techniques such as flame photometry.
Advantages of the DIHEN:
The advantages of the DIHEN are its ability to introduce microvolumes into plasmas at 1-100 µL/min, with relatively small aerosol droplet size, and with nearly 100% use of the sample. The DIHEN operates at extremely low Argon (0.4 L/min) flow. These and other characteristics of the DIHEN can be found in an Analytical Chemistry article titled: ³A Direct Injection High-Efficiency Nebulizer for Inductively Coupled Plasma Mass Spectrometry,² J.A. McLean, Hao Zhang, and Akbar Montaser, Anal. Chem. 1998, 70, 1012-1020.
The instruction manual for the DIHEN is available in pdf form.
DIHEN Adapters:
The DIHEN requires the use of an adapter specifically designed for the demountable torch used by the instrument. Adapters are available for several instruments:
ELAN 5000, ELAN 6000, PE Optima 3000/3000DV, PE Optima 4000, Micromass (requires modified torch), VG (requires modified torch), HP4500/Agilent 7500, Spectro demountable torch, Jobin Yvon demountable torch, and Scimadzu. The DIHEN may be used with the Leeman Labs standard injector adapter. Please inquire about other instruments.
Two accessories well-suited for the DIHEN:
The chromatography union, Fit Kit #1-Micro, is an easy and convenient method to reduce dead volume in the sample introduction system to less than 10 µL. The high pressure reducing union, Fit Kit #2, allows easy connection of a high-pressure Argon line to the sidearm of the DIHEN.