Concentric Glass Nebulizer Research Articles

Combination of high performance liquid chromatography and flame atomic absorption spectrophotometry using a novel nebulizer interface supported T shaped slotted quartz tube for the determination of Vitamin B12

A novel nebulizer interface (NI) was proposed to combine high performance liquid chromatography (HPLC) and flame atomic absorption spectrophotometer (FAAS). A glass concentric nebulizer was linked to T-shaped slotted quartz tube (T-SQT) using a tubing to transfer the liquid solution eluted from the chromatographic system into the atomization region of FAAS system. T-SQT was also used to intensify the interaction of atoms with the hollow cathode lamp light. Vitamin B12 was selected as an analyte to show the applicability of the new hyphenated system. After optimizing some parameters such as mobile phase flow rate and pH, nebulizer gas flow rate, T-SQT height and injection volume, linear range for the analyte was determined between 4.7 and 92 mg/kg as Co. Limit of detection (LOD) and limit of quantitation (LOQ) for the HPLC-NI-T-SQT-FAAS system were calculated to be 1.6 and 5.3 mg/kg as Co, respectively. Recovery studies were also conducted to verify the accuracy and applicability of the developed method for vitamin tablets and excellent percent recovery results (~ 100%) with low standard deviation values were obtained when matrix-matching calibration strategy was performed for each vitamin tablet. A successful separation and detection of the analyte was achieved within 3.0 min that offers high sample throughput. Two different vitamin tablets were analyzed by the optimized hyphenated system. The developed method also provides low usage of sample solution in contrast to conventional nebulizer in the FAAS system.

Adaption of a parallel-path poly(tetrafluoroethylene) nebulizer to an evaporative light scattering detector: Optimization and application to studies of poly(dimethylsiloxane) oligomers as a model polymer

The adaption of an parallel-path poly(tetrafluoroethylene)(PTFE) ICP-nebulizer to an evaporative light scattering detector (ELSD) was realized. This was done by substituting the originally installed concentric glass nebulizer of the ELSD. The performance of both nebulizers was compared regarding nebulizer temperature, evaporator temperature, flow rate of nebulizing gas and flow rate of mobile phase of different solvents using caffeine and poly(dimethylsiloxane) (PDMS) as analytes. Both nebulizers showed similar performances but for the parallel-path PTFE nebulizer the performance was considerably better at low LC flow rates and the nebulizer lifetime was substantially increased. In general, for both nebulizers the highest sensitivity was obtained by applying the lowest possible evaporator temperature in combination with the highest possible nebulizer temperature at preferably low gas flow rates. Besides the optimization of detector parameters, response factors for various PDMS oligomers were determined and the dependency of the detector signal on molar mass of the analytes was studied. The significant improvement regarding long-term stability made the modified ELSD much more robust and saved time and money by reducing the maintenance efforts. Thus, especially in polymer HPLC, associated with a complex matrix situation, the PTFE-based parallel-path nebulizer exhibits attractive characteristics for analytical studies of polymers.

Multi-element analysis of milk by ICP-oa-TOF-MS after precipitation of calcium and proteins by oxalic and nitric acid

In this work a simple technique employing oxalic and nitric acid to cow’s milk samples prior to analysis by inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometry (ICP-oa-TOF-MS) was introduced. After the precipitation of calcium and proteins via oxalic and nitric acid, respectively, the resulting liquid phase was aspirated with a concentric glass nebulizer for ICP-TOF-MS determination of trace elements. Precipitation of proteins is essential for better separation of solid and liquid phase of modified samples. Separation of calcium as a precipitated non-soluble oxalate enables the elimination of spectral interferences originating from different calcium containing species like 40Ca35Cl+, 40Ca37Cl+, 43Ca16O+, 40Ca18O+, 44Ca16O+, 43Ca16O1H+ onto the determination of As, Se, Co and Ni whose assay is more difficult when using conventional quadrupole instruments. High detection capability is further an advantage as the approach enables the analysis without dilution. The methodology may serve, in addition, for a fast and sensitive determination of some other elements. After that, direct, reliable and simultaneous determination of 16 elements (Li, Be, B, V, Cr, Mn, Ni, Co, Ga, As, Se, Mo, Sn, Sb, Cs, Tl) at trace and ultra-trace levels in milk can be performed under optimum instrumental conditions and by using Rh as an internal standard. Accuracy and precision was assessed by measuring NCS ZC73015 milk powder control standard, yielding results in agreement with certified values and RSD <10%. The accuracy was also checked by comparison of the results of the proposed method with those found by a method based on a microwave-assisted digestion of real samples.

Simultaneous electrothermal vaporization and nebulizer sample introduction system for inductively coupled plasma mass spectrometry

The novel analytical application of the combination of an inline electrothermal vaporization (ETV) and nebulization source for inductively coupled plasma mass spectrometry (ICP-MS) has been studied. Wet plasma conditions are sustained during ETV introduction by 200 mL/min gas flow through the nebulizer, which is merged with the ETV transport line at the torch. The use of a wet plasma with ETV introduction avoided the need to change power settings and torch positions that normally accompany a change from wet to dry plasma operating conditions. This inline-ETV source is shown to have good detection limits for a variety of elements in both HNO 3 and HCl matrices. Using the inline-ETV source, improved limits of detection (LOD) were obtained for elements typically suppressed by polyatomic interferences using a nebulizer. Specifically, improved LODs for 51V and 53Cr suffering from Cl interferences ( 51ClO + and 53ClO + respectively) in a 1% HCl matrix were obtained using the inline-ETV source. LODs were improved by factors of 65 and 22 for 51V and 53Cr, respectively, using the inline-ETV source compared to a conventional concentric glass nebulizer. For elements without polyatomic interferences, LODs from the inline-ETV were comparable to conventional dry plasma ETV-ICP time-of-flight mass spectrometry results. Lastly, the inline-ETV source offers a simple means of changing from nebulizer introduction to inline-ETV introduction without extinguishing the plasma. This permits, for example, the use of the time-resolved ETV-ICP-MS signals to distinguish between an analyte ion and polyatomic isobar.

Potential Primary Measurement Tool for the Quantification of DNA

An automated sample introduction system, utilizing a demountable direct injection high-efficiency nebulizer (d-DIHEN), is successfully incorporated for the first time with an inductively coupled plasma optical emission spectrometer (ICP-OES) for the measurement of the phosphorus content in acid-digested nucleotides and deoxyribonucleic acid (DNA). With this experimental setup, the solution uptake rate and volume are reduced from 170 to 30 microL min(-1) and from 10 to 2.4 mL, respectively, thereby reducing the required DNA sample mass for solutions containing 3 microg g(-1) P from 300 to 72 microg of DNA, in comparison to previous analyses in our laboratory using a glass concentric nebulizer with cyclonic spray chamber arrangement. The use of direct injection also improves P (I) 213.617 nm sensitivity by a factor of 4 on average. A high-performance (HP) methodology in combination with the previous sample introduction system and ICP-OES provides simultaneous, time-correlated internal standardization and drift correction resulting in relative expanded uncertainties (% U) for the P mass fractions in the range of 0.1-0.4 (95% confidence level) for most of the thymidine 5'-monophosphate (TMP), calf thymus DNA (CTDNA), and plasmid DNA (PLDNA) analyses. The d-DIHEN with HP-ICP-OES methodology allows for the quantification of DNA mass at P mass fractions as low as 0.5 microg g(-1), further reducing the required DNA mass to 12 microg, with small uncertainty (< or = 0.4%). This successful approach will aid in the development and certification of nucleic acid certified reference materials (CRMs), particularly for these samples that are typically limited in volume.

Photochemical vapor generation of iodine for detection by ICP-MS

A systematic evaluation of UV-photochemical generation of volatile iodine species for detection by ICP-MS is described. Several UV-based systems were studied, the most advantageous design being a modified cyclonic spray chamber fitted with a 6 W mercury pen lamp supplying 1 ml min−1 sample to a glass concentric nebulizer. Optimal conditions utilized a 5% v/v solution of acetic acid as the generation medium. The presence of the UV field enhanced signal intensity approximately 40-fold, providing a (blank limited) limit of detection of 0.7 pg ml−1127I+ and a precision of replicate measurement of 4% RSD at 10 ng ml−1 iodine. Using DRC technology and O2 as the reaction gas, suppression of 129Xe+ provided an estimated LOD of 6 fg ml −1129I+ in aqueous samples.

Preliminary characterization and fundamental properties of aerosols generated by a flow focusing pneumatic nebulizer

A new pneumatic concentric nebulizer (flow focusing pneumatic nebulizer, FFPN), based on the capillary flow focusing effect which produces highly controllable fine aerosols, is presented for the first time for analytical applications. The key aerosol diagnostic data and analytical figures of merit obtained using ICP-AES are presented for the FFPN and compared with a commercially available glass concentric nebulizer (conical nebulizer, CK). To perform a fair comparison, both nebulizers have been run under their own standard working conditions. Under all the conditions studied, the FFPN produces a finer primary aerosol than the conventional pneumatic nebulizer. At a solution uptake rate of 2.0 mL min−1 and a nebulizer gas flow rate of 1.0 L min−1 for the CK, and at a solution uptake rate of 0.2 mL min−1 and a nebulizer gas flow rate of 0.7 L min−1 for the FFPN, the median diameter (D50) values of the primary aerosol are 24.64 μm and 3.82 μm with the CK and FFPN, respectively. The tertiary aerosols of the CK and FFPN studied do not show a substantial difference, the D50 values, under the same operating conditions stated above, being 2.89 μm and 2.87 μm for the CK and FFPN, respectively. Under most of the studied conditions, all the primary aerosols produced by FFPN are contained on droplets smaller than 10 μm. For example, under the above experimental conditions, nearly 22% and 98% of primary aerosol volume is contained on droplets having sizes less than 10 μm for the CK and FFPN, respectively. However, approximately all the tertiary aerosol volume is contained on droplets smaller than this diameter with both nebulizers. This is the result of strong filtering action of the cyclonic spray chamber used, with a cut-off diameter of 15 μm, when CK is used. In general, sensitivities, precision and limits of detection with the FFPN are similar or better than those of the CK, yet with a sample uptake rate of only one-tenth the CK rate.

Electroerosion of metal in aqueous solution for sample introduction into an inductively coupled plasma mass spectrometer

When high current (1–10 A cm −2) is applied between two conductive samples (metals) in aqueous solution, electroerosion occurs on the surface as a result of electrolysis and possibly collisions of dissolved ions with the metal surface. The power supply for the electroerosion apparatus in this work was a modified spark source unit. Current could be varied in intervals of 2.5, 5 and 10 A in either half-wave (unipolar) or full-wave (bipolar) output. The electroeroded metal forms a colloidal suspension in aqueous solution with particle sizes of the order of 1–10 μm and possibly larger. The suspension is readily dissolved using a small amount (100 μl) of concentrated acid (HCl or HNO 3) prior to analysis. Electroerosion of steel and brass in aqueous solution is described both for rapid sample dissolution and as a solid sampling approach for ICP-MS. Some of the electroerosion properties described in this paper include rates of erosion as a function of gap between the conductive samples and solution conductivity. Rates of electroerosion decreased from 120 to 30 μg s −1 as the gap was increased from 2 to 5 mm. Rates of electroerosion also increased significantly from 200 to 1000 μg s −1 as the conductivity of the electroerosion solution increased from 0.01 to 0.05 M NaCl. Interfacing the electroerosion apparatus to an ICP-MS was straight forward, as no special equipment was required. Therefore, the electroerosion apparatus can be used for rapid ‘on-line’ sample dissolution prior to introduction into an ICP. ICP-MS time profiles of selected metals in stainless steel 308L illustrate the behavior of 52Cr +, 55Mn + and 60Ni + during a typical electroerosion cycle. Aspiration of the colloidal suspension into the ICP did not appear to load the plasma significantly, however, all of the metals produced noisy signals (±10%). A glass concentric nebulizer was used without clogging, so it is likely that the heterogeneous nature of the colloidal suspension caused this effect.

Temporal responses of spectral line intensities emitted by d.c. arc plasma with aerosol supply studied by power interruption technique

The responses to the fast interruption of the arc current have been studied for the spectral line intensities of several elements emitted by U-shaped direct current (d.c.) arc plasma with aerosol supply. The arc was burned at atmospheric pressure. Solutions containing the investigated elements were introduced with a concentric glass nebulizer into the argon stream of 2.7 l min −1. The arc current of 6 A was interrupted in periods that lasted up to 200 μs. At the moment of power interruption, the spectral line intensities are either suddenly increased indicating Saha balance or suddenly decreased indicating Boltzmann balance. Plots of intensity vs. time are used to evaluate the mechanisms that maintain the populations of excited states in the stationary state and processes occurring in the plasma during the power-off period. Excited levels of the elements with high ionization energies, like Ar, H and O, are predominantly populated by three-body recombination process i.e. they are controlled by the Saha balance. Excited levels of elements with medium ionization energies are predominantly populated by collisions with electrons i.e. controlled by the Boltzmann balance. Some of the spectral lines of C, P and Hg with high-excited levels missed the sudden intensity change, a cooling jump, which could be interpreted by the presence of two opposite mechanisms, Saha and Boltzmann balances, that cancel out the effect. Spectral line responses of easily ionized elements were found to depend on the plasma region. In a 2-mm axis region, the intensities do not show a cooling jump, but increase slowly during the power-off period. At medium distances from the arc axis, the spectral lines show typical Boltzmann type response. Farther to the arc periphery, where the electron concentration is very low but emission is still high, the power interruption does not influence the intensities and this indicates that the excitation is not prevailed by electron collisions.

Simple interface for capillary electrophoresis–inductively coupled plasma atomic emission spectrometry

A simple interface has been developed to couple capillary electrophoresis (CE) to inductively coupled plasma atomic emission spectrometry (ICP-AES) for metal speciation. A concentric glass nebulizer with elongated tip is used as the CE–ICP interface. The CE capillary is the central tube of the nebulizer. A platinum wire is wrapped across the exit end of the CE capillary to provide electrical connection to the CE power supply. No sheath flow of buffer solution is needed. A simple cooling system has also been developed. A peristaltic pump circulates water through a plastic tube that encloses the section of the CE capillary between the CE instrument and the ICP spectrometer. Characteristics of the CE–ICP interface, e.g., elution time, nebulization and transport efficiency and peak broadening, versus carrier gas flow-rate have been studied. Comparisons to a previous design with the Pt electrode inserted into the end of the CE capillary are made where appropriate. The reproducibility (RSD) in ICP emission intensity of the system is <4%. Detection limits of Cr and Cu are ∼5 ng/ml.

Preliminary characterization of a laboratory-constructed, easily disassembled concentric pneumatic nebulizer for inductively coupled plasma mass spectrometry

A low-cost concentric nebulizer that can be disassembled and reassembled is described. This device uses commercially available fused silica tubing as an inner capillary and a borosilicate glass serological pipet as an outer capillary. The device is readily constructed in <15 min with commercially available components; no specialized skills such as machining, injection molding, or glassworking are required. The easily disassembled concentric nebulizer has been compared to a commercially available glass concentric nebulizer using ICP-MS; similar characteristics for M+ and MO+ intensities versus nebulizer Ar flow rate were observed. The commercially available glass concentric nebulizer was found to produce higher peak M+ signals amounting to 29–58 and 23–29 relative percent difference at liquid introduction rates of 0.27 and 1.08 ml min−1, respectively; this difference may arise from differences in the inner capillary wall thickness. The easily disassembled nebulizer yielded satisfactory 238U∶235U measurements with precision limited to ≈0.3% RSD.

A comparison of nebulizers for microbore LC-ICP-MS with mobile phases containing methanol

A comparison was made between a glass concentric nebulizer, a microconcentric nebulizer (MCN), and a Micro Mist nebulizer for the introduction of mobile phases containing varying concentrations of methanol. For all nebulizers investigated, the signal remains constant with increasing sample flow rate at methanol concentrations greater than 20% of the mobile phase, even though the rate that sample reaches the plasma increases at increasing flow rates. A separation of tributlytin chloride (TBT) and triphenyltin chloride (TPhT) on a microbore reversed-phase HPLC column using a mobile phase consisting of 70% methanol, 29% water, 1% glacial acetic acid and 4 mM ion pair reagent was investigated. At a flow rate of 0.2 ml min−1, the absolute detection limits for the MCN were slightly higher than those obtained with the Micro Mist nebulizer or the glass concentric nebulizer. Precision and the linearity of the calibration curves were comparable for all three nebulizers.

Improved measurement of iodine in food samples using inductively coupled plasma isotope dilution mass spectrometry.

A new ICP-MS method for the determination of iodine in food samples is presented. The method makes use of a new miniature cyclonic spray chamber and a concentric glass nebulizer that is designed for low sample uptakes and is operated in a self-aspirating mode. As a consequence the wash-out was accelerated over conventional systems. This configuration allows the direct determination of iodine in mineralized solutions following digestion with nitric acid only. No strong oxidizing reagents such as perchloric acid or lengthy sample preparation were necessary to alter the chemical form of potentially volatile species. The isotope dilution technique using the long-lived isotope 129I was applied to obtain freedom from matrix effects. The present study reports on results for total iodine in selected nutritional and biological reference materials and makes a comparison with instrumental neutron activation analysis.

Determination of trimethylselenonium iodide, selenomethionine, selenious acid, and selenic acid using high-performance liquid chromatography with on-line detection by inductively coupled plasma mass spectrometry or flame atomic absorption spectrometry

An analytical method has been developed for the determination of selenious acid, selenic acid, trimethylselenonium ion, and selenomethionine. The four selenium compounds were separated by HPLC on a column (25 cm×4 mm I.D.) of the anion-exchanger ESA Anion III with a mobile phase (1.5 ml/min) of 0.0055 M ammonium citrate (pH 5.5). Detection was carried out using an on-line inductively coupled plasma mass spectrometer (ICP-MS) or a flame atomic absorption spectrometer (FAAS) as the selenium-specific detector. The chromatographic parameters and the chemical factors affecting the separation of the selenium species were optimized. The four selenium compounds could be separated within 8 minutes. The detection limits of the coupled HPLC–FAAS system were approximately 1 mg Se/l for each compound (100 μl injection), estimated as three times the base-line noise of the chromatograms. More powerful selenium detection was achieved with an ICP-MS. Selenium was measured at m/ z 78. To increase the nebulization efficiency, the Meinhard concentric glass nebulizer was replaced by an ultrasonic nebulizer. The ICP-MS signal intensity was increased with the ultrasonic nebulization by a factor of 7 times for selenious acid and 24 to 31 times for trimethylselenonium ion, selenomethionine, and selenic acid compared to that with the Meinhard nebulization. The detection limits achieved by the HPLC–ICP-MS with the ultrasonic nebulization were 0.08 μg Se/l for trimethylselenonium ion, 0.34 μg Se/l for selenious acid, 0.18 μg Se/l for selenomethionine, and 0.07 μg Se/l for selenic acid, respectively.

Determination of metals in saline and biological matrices by axial inductively coupled plasma atomic emission spectrometry using microconcentric nebulization

An axial inductively coupled plasma atomic emission spectrometer equipped with a commercially available microconcentric nebulizer (MCN) was evaluated for the determination of metals in saline and biological samples. The performance of the MCN was optimized regarding the sample uptake rate and nebulizer pressure in terms of signal intensity and signal-to-background ratio. The effect of increasing salt concentrations was also studied. The results were compared with those obtained with a standard concentric glass nebulizer (CGN) for sample volumes, sensitivity and stability. The MCN was shown to reduce the sample consumption from several milliliters to a few hundred microliters for multi-element analyses. The analytical performance with the MCN was generally poorer than with the CGN, but the magnitude of the effects is element dependent. For the 18 elements studied, the detection limits range from 0.05 µg l–1 (Mn) to 30.48 µg l–1 (Ca) for the CGN and from 0.13 µg l–1 (Mn) to 173.66 µg l–1 (Na) for the MCN. Increasing the salt concentration decreases both the sensitivity and signal stability obtained with both nebulizers, but the effects are more pronounced for the MCN. The method was further evaluated by analyzing three BCR reference materials: CRM 63 Milk Powder, CRM 185 Bovine Liver and CRM 278 Mussel Tissue. Overall, the results obtained with both nebulizers showed good agreement with the certified values.

Retention behavior of inorganic and organic selenium compounds on a silica-based strong-cation-exchange column with an inductively coupled plasma mass spectrometer as selenium-specific detector

The retention behavior of eight selenium compounds (selenous acid, selenic acid, selenocystine, selenohomocystine, selenomethionine, selenoethionine, trimethylselenonium iodide, and dimethyl(3-amino-3-carboxy-1-propyl)selenonium iodide) with aqueous solutions of pyridine (20 mmol/l) in the pH range 2.0–5.7 on a Supelcosil LC-SCX cation-exchange column was investigated. An inductively coupled plasma mass spectrometer was employed as the selenium-specific detector. To increase the nebulization efficiency, the Meinhard concentric glass nebulizer was replaced by a hydraulic high-pressure nebulizer. At pH 5.0, seven selenium compounds could be separated within 400 s, but selenohomocystine and selenomethionine had the same retention time. Selenomethionine can be separated from selenohomocystine with an aqueous solution of pyridine (20 mmol/l) adjusted with formic acid to pH 2.0. At 1 ng Se ml −1, the relative standard deviations ( n=5) of the signal area for the eight selenium compounds ranged from 7 to 11%, and at 50 ng Se ml −1 from 0.6 to 2.6%.

Low-flow interface for liquid chromatography–inductively coupled plasma mass spectrometry speciation using an oscillating capillary nebulizer

The application of a novel nebulizer, the oscillating capillary nebulizer (OCN), is described for use in speciation studies. The nebulizer has certain features which make it very suitable for this application, without modification, at both micro-flows (1 µl min–1) and macro-flows (1 ml min–1). Short- and long-term precision at typical operating flows are comparable to a normal (1 ml min–1) concentric glass nebulizer. Column-to-nebulizer dead volume is approximately 1 µl. The narrow drop size distribution for the nebulizer at low flows leads to excellent sensitivity when coupled to a micro-LC column. Post-column peak broadening introduced by the interface is minor at flows 5 µl min–1, but widens the peaks noticeably at flows between 1 and 5 µl min–1. The very high efficiency of the nebulizer at flows <50 µl min–1 is exemplified by the fact that no drain is necessary at these flows in the open spray chamber, as no visible liquid condenses on the chamber walls. The ICP-MS response for the OCN (counts per ng of Se injected) does not change when water is replaced by methanol as solvent, whereas with a conventional nebulizer, a solvent change of this type inevitably results in a significant change in response. The OCN was used for the reversed-phase LC separation of a mixture of five organic Se compounds of pharmacological significance, at flows of 12, 50 and 400 µl min–1. With use of a 0.5 mm id column, a flow rate of 12 µl min–1 and a 60 nl injection, good peak separation was found, with an average efficiency of ≈ 10000 plates and a detection limit of around 30 pg.

Interface for Capillary Electrophoresis and Inductively Coupled Plasma Mass Spectrometry

A modified concentric glass nebulizer interface for capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry is described. A conductive liquid coaxial sheath in the nebulizer was used as the return ground for the CE capillary. The variable position of the CE capillary in the nebulizer interface made a compromise between separation resolution and signal intensity possible. Negative reservoir pressure was applied to counterbalance nebulizer suction to the CE capiary and restore resolution. Metallothionein and ferritin were evaluated to characterize the interface. Metallothionein isoforms and ferritin were separated and their metal contents identified. Detection limits achieved for 57 Fe and 114 Cd in ferritin were 184 and 4.0 fg, respectively, for 74 nL injections.

Different sample introduction systems for the multaneous determination of As, Sb and Se by microwave-induced plasma atomic emission spectrometry

The determination of hydride-forming elements using different sample introduction procedure into microwave-induced plasmas (MIPs) has been studied. For the determination of As, Sb and Se analyte introduction was accomplished with a pneumatic concentric glass nebulizer,a graphite furnace, or with thydride generation followed by cold-trapping or hot-trapping in a graphite furnace. The detection limits obtained with different types of low power MIPs (toroidal, 1 or 3 filament MIPs) operated in a TM 010 cavity according to Beenakker also were investigated. The contruction of the flow system used for preconcentration and the effects of reagent concentration, gas flow rates as with MIP-atomic emission spectrometry (AES) were investigated. The trapping of the hydrides followed by their vaporization showed substantial advantages over the other introduction systems investigated, especially with respect to power of detection. Further, mutual interferences being a big problem in atomic absorption spectrometry are widely absent in MIP-AES. Under compromise operating conditions the detection limits for As, Sb and Se are 0.4; 0.35; 0.25 ng ml −1 respectively, while the sample volume can be varied from 0.05 ml up to several millilitres.

The Effect of Nebulizer Structure on Flame Emission

The emission-producing capabilities of twelve different models of the MEINHARD™ concentric glass nebulizer were evaluated in a flame photometer in an effort to correlate nozzle geometry with emission performance. Signal intensity, stability, and internal consistency within a model were compared. Sensitivity, defined as signal intensity per mL/min sample flow, was also computed and compared. It was expected that relative performances in the flame would provide an index to relative performances in plasma or other emission excitation sources, and results would thus serve as an aid to nebulizer selection for other atomic analytical techniques including ICP. A new nebulizer, the TR-50-K2, generated signals up to 64% higher than those of the TR-30-A3 and up to 25% higher than those of the TR-30-A2 (and TR-50-C1), which produced the highest signals of currently available models.