Nebulizer Flow Rate Research Articles

Analysis of cerium-substituted yttrium iron garnets by inductively coupled plasma atomic emission spectrometry with preliminary microwave decomposition

An analytical procedure for inductively coupled plasma atomic emission (ICP-AES) analysis of iron garnets of the composition Y3 – xCexFe5 – yGayO12, where x = 0.4 – 0.5 and y = 2.4 – 2.6 with preliminary microwave decomposition of the sample is described. The compositions of acid mixtures (HCl/HNO3), as well as modes of microwave heating (holding time and temperature), providing complete dissolution of the samples are proposed. In addition to optimized sample preparation, conditions for ICP-AES analysis of cerium-doped yttrium iron garnets were studied. The effect of matrix components (Y, Ce, Fe, Ga) on the determination of doping elements was revealed and studied. The operating parameters of the spectrometer (ICP power and nebulizer flow rate) have been substantiated, which make it possible to reduce the matrix effect of Fe, Ga, Y, Ce on the elements Na, Mg, Al, Si, P, K, Ca, Sc, Cr, Mn, Co, Ni, Cu, Zn, Se, Cd, Sn, Te, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Pb in iron yttrium garnets by the ICP-AES. ICP-AES measurements were performed in the axial and radial mode for trace elements and in the radial mode for matrix elements. The limits of quantification (LOQs) of most elements ranged within n × 10–5 – n × 10–4 wt.%. The accuracy is confirmed by the spike recovery test. The relative standard deviation is in the range of 1 – 5% depending on the selected plasma view mode and the analyzed analytes. The developed method makes it possible to determine macro- and microcomponents in yttrium iron garnets in a wide range of concentrations with a high accuracy.

Assessment of total sample consumption infrared-heated system for minimization of matrix effects in ICP-tandem mass spectrometry

A total sample consumption infrared-heated system (IR-TSC) has been coupled to ICP-tandem mass spectrometry (ICP-MS/MS) for the first time. The objective of this study was to assess the analytical performance of the IR-TSC system, in terms of analytical figures of merit and mitigation of matrix effects. Twenty-seven elements have been determined: Ag, Al, As, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, K, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, Tl, V and Zn. Different operating conditions, including nebulization flow rate and spray chamber temperature, were optimized to improve sensitivity, signal stability, and plasma thermal conditions. The results showed that the infrared-heated sample introduction system improved the signal intensity by a factor of 2 to 4 compared to a conventional sample introduction system, whereas the limits of detection (LODs) improved by a factor going from 1.2 (Ba) to 3.3 (Cr) for a sample containing 2% HNO3. Meanwhile, for a 10% ethanol sample the improvement factor ranged from 1.4 (Ti) to 3.8 (Cr). Matrix effects for solutions containing inorganic acids or high content of sodium (2% HNO3, 10% HNO3, 20% HNO3, 10% HCl; 500 mg kg−1 Na, 500 mg kg−1 Na + 10% HNO3) were mitigated under optimum conditions (IR-TSC at 125 °C). Meanwhile, for solutions containing organic solvents (10% ethanol, 10% acetic acid, and 10% formic acid) it was not possible to eliminate matrix effects, even when applying an internal standard. For Se and As, elements spectrally interfered, the combination of IR-TSC sample introduction system with oxygen as reaction/collision gas mode in ICP-MS/MS provided accurate results. For 10% HNO3 and 10% HCl relative intensities values, calculated taking the signal intensity obtained for 2% HNO3 as reference, were close to the unity. Environmental and clinical control and certified reference materials were analyzed by means of an external calibration approach, with most of the elements showing concentrations not significantly different from the certified values. Finally, the IR-TSC was tested on twelve real samples, including seawater, surface water, peritoneal fluid, seminal plasma, wine, and bioethanol samples, demonstrating the system potential in different application fields.

Evaluation of an Inductively Coupled Plasma–Atomic Emission Spectrometry (ICP-AES) Method for the Determination of Macro and Microelements in Trifolium L. Species

This study aimed optimizes the inductively coupled plasma–atomic emission spectrometry (ICP-AES) conditions for the determination of macro and microelements in the flowers and leaves of Trifolium species. After the optimization of instrumental parameters, plasma robustness was achieved under the following conditions: RF power 1350 W, nebulizer flow rate 0.5 L min−1, coolant gas flow rate 12 L min−1, auxiliary gas flow rate 0.5 L min−1, flush pump rate 100 rpm, analysis pump rate 50 rpm, sample flow 0.5 mL min−1, and sample uptake delay 30 s. The limits of detection (LOD) and limits of quantification (LOQs) were lower than literature values. The most abundant microelement in leaves is Ca, followed by K, Mg, P, and Na, and in flowers was K, followed by Ca, P, Mg, and Na. The average contents of microelements decreased in the orders S > Fe > Si > Al > Zn > Mn > Cu > Ni > Co > Pb > Cr > As > Cd for flowers and S > Fe > Si > Mn > Al > Zn > Cu > Ni > Co > Pb > Cr > As > Cd for leaves. Chemometrics were used for grouping samples based upon the elemental contents.

High temperature total consumption sample introduction system coupled to microwave plasma optical emission spectrometry (MIP-OES) for the analysis of aqueous samples

The high temperature torch integrated sample introduction system (hTISIS) is coupled to microwave plasma optical emission spectrometry (MIP-OES) for the first time. The goal of this work is to develop an accurate analysis of digested samples under continuous sample aspiration mode by coupling the hTISIS to a MIP-OES instrument. To achieve this, different operating conditions such as, nebulization flow rate, liquid flow rate and the spray chamber temperature were optimized in terms of sensitivity, limits of quantification (LOQs) and background equivalent concentration (BECs) for the determination of Ca, Cr, Cu Fe, K, Mg, Mn, Na, Pb and Zn, and these values were compared with those reported with a conventional sample introduction system. Under optimum conditions (0.8–1 L min−1, 100 μL min−1 and 400 ᵒC, respectively), the hTISIS improved MIP-OES analytical figures of merit and shortened 4-times wash out times with respect to a conventional cyclonic spray chamber, reporting an enhancement factor in the sensitivity among 2–47 times and LOQs from 0.9 to 360 μg kg−1. Once the best operating conditions were set, the magnitude of the interference caused by 15 different acid matrices (2, 5 and 10% w/w of HNO3, H2SO4, HCl and mixtures of HNO3 with H2SO4 and HNO3 with HCl) was significantly lower for the former device. Finally, 6 different digested oily samples (used cooking oil, animal fat, corn oil and the same samples after a filtration step) were analyzed by means of an external calibration approach based on the use of multielemental standards prepared in 3% (w/w) HCl solution. The obtained results were compared against those supplied by a conventional methodology employing an inductively coupled plasma optical emission spectrometry, ICP-OES, instrument. It was clearly concluded that the hTISIS coupled to MIP-OES afforded similar concentrations as compared to the conventional methodology.

Optimization of ICP-OES\u2019S parameters for uranium analysis of rock samples

Currently, the quantitative analysis methods for uranium that are widely used in laboratories, such as the volumetric method and inductively coupled plasma mass spectrometry (ICP-MS) cannot achieve low cost, simple operation, and little influence by other elements. The inductively coupled plasma optical emission spectrometer (ICP-OES) has a wide linear range, and high stability, and can be used to identify multiple elements simultaneously. However, when ICP-OES is used for quantitative analysis of uranium, the settings for the RF power, nebulizer flow, and pump rate can affect the analysis results. In this work, these parameters were carefully optimized for identifying uranium. Based on experiments, we selected two spectrum peaks 409.014 nm and 424.167 nm for quantitative analysis with the lowest interference. The optimal parameters obtained are atomizer flow rate of 0.75 L/min, a sample pumping rate of 1.6 mL/min, and a high-frequency power of 1400 W. Then we compared the accuracy of the volumetric method, ICP-MS method and ICP-OES method with the optimized parameter for analysis of experimental samples and references. The results showed that the ICP-OES with the optimized parameters proposed in this paper can be used to perform a convenient, quick, and efficient quantitative analysis of uranium in minerals.

Matrix effects in atmospheric pressure nitrogen microwave induced plasma optical emission spectrometry

The matrix effects in MIP OES arising in the presence of elements with Eion 5.13–9.39 eV (Na, Cu, Pb, Cd, Zn) depending on the concentration, nebulization flow rate, and plasma power were studied.

Effect of nebulizer type, delivery interface, and flow rate on aerosol drug delivery to spontaneously breathing pediatric and infant lung models.

Different types of nebulizers, interfaces, and flow rates are used to deliver aerosolized medications to children. The purpose of this study was to determine the effect of nebulizer type, delivery interface, and flow rate on aerosol drug delivery to spontaneously breathing pediatric and infant lung models. A teaching mannequin was attached to a sinusoidal pump via a collecting filter at the bronchi to simulate a spontaneously breathing child (Vt: 250 mL, RR: 20 bpm and Ti: 1 second) and infant (Vt = 100 mL, RR = 30 bpm, Ti: 0.7 seconds). Albuterol sulfate was nebulized with jet (Misty Max 10; Cardinal Health) and mesh (Aerogen Solo; Aerogen) nebulizers using a low-flow nasal cannula (LFNC; Hudson), a high-flow nasal cannula (HFNC; Fisher & Paykel), face mask (FM; Hudson), and mouthpiece (MP; Cardinal Health). While all interfaces were used in the pediatric study, only LFNC, HFNC, and FM were tested in the infant study. The mesh nebulizer was tested at 2, 4, and 6 L/min with LFNC, 4 and 6 L/min with HFNC, and 6 L/min with FM and MP. The jet nebulizer was operated at 6 and 8 L/min with FM and 6 L/min with LFNC, HFNC, and MP (n = 5). The drug was eluted from the filter and analyzed by spectrophotometry. Factorial analysis of variance and post hoc comparisons were used for data analysis. P < .05 was considered statistically significant. Delivery efficiency of mesh nebulizers is two to fourfold more than jet nebulizers used with HFNC, FM, and MP. No statistical difference was found between jet and mesh nebulizers used with LFNC in infants (P = .643) and pediatrics (P = .255). Aerosol delivery with MP was the best compared to other interfaces used in pediatrics (P < .05). As the second-best interface in aerosol drug delivery, the delivery efficiency of FM was greater than HFNC (P = .0001) and LFNC (P = .0001). Increasing flow rate with LFNC and HFNC decreased aerosol delivery with the mesh nebulizer in both infants and pediatrics. The type of nebulizer, delivery interface, and flow rate used in the treatment of children affect aerosol drug delivery.

Optimization of simultaneous determination of metals in commercial pumpkin seed oils using inductively coupled atomic emission spectrometry

In this work, the inductively coupled plasma atomic emission spectrometry (ICP-AES) was developed and validated for determination of 27 metals in nine pumpkin oils from two production processes (cold pressed and roasted). A microwave assisted digestion was applied for the dissolution of the samples. To evaluate plasma robustness and analytical performance, the Mg II 280.270 nm/Mg I 285.213 nm (Mg II/Mg I) line intensity ratio was used. The robust plasma conditions in axial/radial view mode were reached at an RW power of 1150 W and an argon nebulizer flow rate of 0.5 L/min. The method is evaluated by application of the standard addition method and by recovery test. In general, the recoveries for all elements in pumpkin seed oils were between 90% and 110% except, only for Cd, Pb and As they were <90% and >110%. The most abundant element is K followed by, Mg, P, Ca and Na. Pumpkin seed oils were also found to be a good source of Fe, Zn, Cu and Mn. The highest levels of analyzed elements were found in pumpkin seed oils producing from the roasted pumpkin seed paste. In all samples, the content of heavy metals was below the recommended tolerable levels proposed by Joint FAO/WHO Expert Committee on Food Additives and does not a pose a health risk for the consumer. The levels of the metals in pumpkin seed oils were also compared with those reported by the literature. Cluster analysis (CA) of the analytical data confirmed the observed differences between oils from two production processes.

Comparison of analytical performances of inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry for trace analysis of bismuth and bismuth oxide

The paper presents а comparison of analytical performances of inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) for trace analysis of high purity bismuth and bismuth oxide. Matrix effects in the ICP-MS and ICP-AES methods were studied as a function of Bi concentration, ICP power and nebulizer flow rate. For ICP-MS the strong dependence of the matrix effects versus the atomic mass of analytes was observed. For ICP-AES the minimal matrix effects were achieved for spectral lines of analytes with low excitation potentials. The optimum degree of sample dilution providing minimum values of the limits of detection (LODs) was chosen. Both methods let us to reach LODs from n·10−7 to n·10−4wt% for more than 50 trace elements. For most elements the LODs of ICP-MS were lower in comparison to ICP-AES. Validation of accuracy of the developed techniques was performed by “added-found” experiments and by comparison of the results of ICP-MS and ICP-AES analysis of high-purity bismuth oxide.

A Simple and Reliable Method to Determine 16 Trace Elements by ICP OES in Ready to Drink Beverages

In this work, multivariate experiments were carried out to optimize a simple and reliable method for determination of 16 trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Sb, Se, Sr, Sn, and Zn) in ready to drink beverages by ICP OES. The multivariate methodology to optimize ICP OES parameters consisted in a 24-1 and a 23 central composite design, where the variables studied were radio frequency power, nebulization flow rate, auxiliary argon flow rate, and argon plasma flow rate and the responses were signal to background ratio (SBR) and the plasma robustness. The compromised conditions were RF power, 1.35 kW; nebulization flow rate, 0.50 L min−1; auxiliary argon flow rate, 0.55 L min−1; and argon plasma flow rate, 12.0 L min−1. Under these conditions, the microwave digestion using diluted oxidant mixture provided recoveries between 79 and 110% for quantifiable trace elements in two reference materials (corn brand and tea leaves) and 81 and 118% in spiked experiments. The method was successfully applied to 10 samples of ready to drink beverages (fruit juice, soy-based beverages, and tea), and the levels found were below the maximum allowed for inorganic contaminants by Brazilian, European, and MERCOSUL regulations.

A quantitative approach for Cd, Cu, Fe and Mn through laser ablation imaging for evaluating the translocation and accumulation of metals in sunflower seeds

The uptake and accumulation of Cd in sunflower seeds represents an important pathway for imputing potentially toxic metals into human and animal food. In this way, bioimaging of Cd and micronutrients (Cu, Fe and Mn) in the seeds of sunflower grown in soil contaminated with Cd are performed. For this task, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used in quantitative approach, considering four groups: precursor, control, Cd-low (50mg) and Cd-high (700mg). For attaining our proposals, ICP-MS (nebulizer and auxiliary flow rates and radiofrequency power) and LA (laser intensity, frequency and spot size) parameters were optimized, and the analytical signal improved to 197%, 217%, 232%, and 283%, for 57Fe, 112Cd, 55Mn and 63Cu, respectively. The accuracy of proposed method using LA-ICP-MS is evaluated comparing the CRM results (Tomato leaves, NIST SRM 1573a). No difference is found at 95% confidence level. Regarding Cd accumulation in sunflower seeds, the results indicated that cadmium is translocated to seeds, and the cotyledons showed the highest concentration (Cd-high group), ranging from 10 to 20µgg−1. Considering both total concentration and the distribution in the seeds, Cd uptake is responsible to the homeostasis misbalance of micronutrients, which play an essential role in the sunflower metabolism. Such results highlight the importance of bioimaging evaluation, in the translocation and accumulation of metals, contributing to expand the information available of this culture.

Errors in Isotope Dilution Caused by Matrix-induced Mass Bias Effect in Quadrupole Inductively Coupled Plasma-Mass Spectrometry

Yong-Nam PakDepartment of Chemistry Education, Korea National University of Education, Chung Buk 363-791, KoreaE-mail: pakyn@knue.ac.krReceived July 2, 2014, Accepted August 8, 2014Matrix-induced mass bias and its effect on the accuracy of isotope ratio measurements have been examined fora quadrupole-based inductively coupled plasma-mass spectrometer (Q ICP-MS). Matrix-induced mass biaseffect was dire ctly proportional to % mass d ifference, and its magnitude varied for element and nebulizer flowrate. For a given element and conditions in a day, the effect was consistent. The isotope ratio of Cd106/Cd114under 200 µg g

Direct determination of gallium in bauxite employing ICP OES using the reference element technique for interference elimination

The determination of gallium in bauxite samples using inductively coupled plasma optical emission spectrometry (ICP OES) is complicated because aluminum in high concentrations interferes strongly in this analysis. This paper proposes a direct method for the determination of gallium in bauxite samples by ICP OES employing the reference element technique for correction of aluminum interference.The experimental parameters: hydrochloric acid concentration used for preparation of gallium standard solutions and bauxite samples, nebulizer flow rate and RF power were optimized by multivariate technique. Firstly, a factorial design was performed for preliminary evaluation. Afterward, a Box–Behnken design was also performed for determination of the critical conditions for these factors. Box–Behnken design is a chemometric technique that in the last years has been often used for optimization of analytical methods.The procedure proposed using the established conditions (in presence of yttrium and/or scandium as reference element) allows the determination of gallium with limits of detection and quantification of 0.0006 and 0.0019mgL−1 and precision expressed as relative standard deviation of 4.37 and 1.78% for bauxite samples with gallium content of 21.00 and 36.00mgKg−1. For sample mass of 0.20g the limits of detection and quantification are 0.042 and 0.140mgKg−1, respectively. The accuracy of the method was evaluated and confirmed using standard reference materials of alumina and marine sediment.The method proposed was applied for the determination of gallium in five bauxites, having yttrium and scandium as reference element, being that the sample preparation was done employing microwave-assisted digestion. The gallium content in the five samples varied from 19.70 to 100.59mgKg−1. These concentrations are in agreement with the data reported by literature.

An Easy and Fast Procedure for the Determination of Ca, Cu, Fe, Mn, Mg, Na, K and Si in Biodiesel by ICP OES Using Emulsification as Sample Preparation Strategy

It is presented an alternative procedure for preparation of biodiesel samples for elemental determination by inductively coupled plasma optical emission spectrometry (ICP OES), based on the sample (10% m/v) emulsion formation with formic acid (15% v/v) and Triton X-100 (0.1% m/v). These concentrations were optimized and the stability of emulsified aqueous standards and samples was found to be of at least 3 h. Experimental conditions (1500 W of RF power and 0.5 L min-1 of Ar nebulizer flow rate) were optimized from those recommended by the equipment manufacturer, with a solution containing 10 mg L-1 of each analyte prepared with mineral oil in the same conditions of the emulsion. Matrix effects were investigated by observing the slopes of analyte addition curves for different biodiesel samples. Results showed that external calibration with inorganic aqueous standard solutions in the emulsion medium should be used. Limits of detection obtained (in mg kg-1) were 0.121, 0.008, 0.006, 0.001, 0.006, 0.071, 0.241 and 0.024 for Ca, Cu, Fe, Mn, Mg, Na, K and Si, respectively. The accuracy of the procedure for Ca, Mg, K and Na was assessed by the analysis of a multi-element standards B100 biodiesel (Conostan) and the recoveries ranged from 91 to 107%. The proposed procedure used low toxicity reagents and showed to be a simple and straightforward alternative of sample preparation for metal determination in biodiesel by ICP OES with limits of detection adequate for those analyses.

Multielemental Determinations in Chocolate Drink Powder Using Multivariate Optimization and ICP OES

In this work multivariate experiments were conducted to optimize the operating conditions for inductively coupled plasma optical emission spectrometry (ICP OES) for multielemental determinations in chocolate drink powder. The operating conditions were investigated using a 2(3) central composite design, where the variables studied were radio frequency power, nebulization flow rate, and auxiliary argon flow rate. The effects of these parameters on plasma robustness and on signal to background ratio (SBR) were considered in parallel, allowing the evaluation of robustness and detectability using few and fast experiments to select the best conditions for the determination of the analytes. In this case, the proposed experiments were applied to the optimization of a method aimed at the determination of Al, Ba, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Pb, V, and Zn in chocolate drink powder. The compromise conditions that allowed obtaining a robust and sensitive analytical method were radio frequency power of 1200 W, nebulization flow rate of 0.6 L/min, and auxiliary argon flow rate of 0.3 L/min. Using these conditions, recoveries between 95 and 105% and relative standard deviations lower than 5% were obtained for the majority of the analytes. The proposed method was successfully applied to the analysis of 15 samples of chocolate drink powder. The highest concentrations of metallic species were found in diet and light products.

Determination of inorganic contaminants in glue by inductively coupled argon plasma optical emission spectrometry

A closed vessel method using a microwave oven was developed for the determination of As, B, Ba, Bi, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, Sn and Sb by Inductively Coupled Argon Plasma Optical Emission Spectrometry (ICP OES). The method was applied to samples of polyvinyl acetate-based glue in water emulsions. Parameters such as wavelength, nebulization pressure and RF power were optimized and the residual acidity after the digestion process was determined. The addition of internal standards was evaluated and the accuracy of the proposed method was verified with addition and recovery experiments and also with certified reference materials, achieving good results. Using a nebulization flow rate of 0.73Lmin−1and a RF power of 1200W it was possible to obtain adequate values for limit of detection and limit of quantification as well as recovery values in the range of 80–106%, for all the analytes. The analysis of coloured glue samples (white, black, blue, yellow, red and green), widely used by children, showed no contamination by the elements studied.

Feasibility of the internal standardization in direct determination of arsenic in wine samples by inductively coupled plasma atomic emission spectrometry

In this study, a fast and simple method is proposed for determination of arsenic in wine employing inductively coupled plasma atomic emission spectroscopy and internal standard technique. First Co, Bi, V and Y were evaluated as internal standards to minimize transport interferences. All samples and reference solutions were automatically spiked by autosampler, eliminating the need for manual dilutions. The result demonstrated that vanadium can be used as an internal standard. The experimental parameters (plasma power and nebulization flow rate) were optimized. The relative standard deviations (R.S.D) of measurements varied from 1.1 to 6.0% and 3.2 to 8.7% (n=12) with and without internal standardization, respectively. Recoveries in the 95–103% range for As spiked samples were obtained.

Influence of Impactor Operating Flow Rate on Particle Size Distribution of Four Jet Nebulizers

When a nebulizer is evaluated by the Andersen Cascade Impactor (ACI), the flow rate is generally maintained at 28.3 L/min, as recommended by the manufacturer. However, the nebulizer flow rate that a patient inhales is only around 18 L/min. Because the drive flow of a nebulizer is approximately 6–8 L/min, the nebulized drug is mixed with outside air when delivered. Evaluating impactor performance at the 28.3 L/min flow rate is less than ideal because an additional 10 L/min of outside air is mixed with the drug, thereby affecting the drug size distribution and dose before inhalation and deposition in the human lung. In this study we operated the ACI at an 18.0 L/min flow rate to test whether the effect of the changing ambient humidity was being exaggerated by the 28.3 L/min flow rate. The study was carried out at three different relative humidity levels and two different impactor flow rates with four commercially available nebulizers. The mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD) of the droplets were found to increase when the impactor was operated at a flow rate of 18 L/min compared to that of 28.3 L/min. The higher MMAD and GSD could cause the patient to inhale less of the drug than expected if the nebulizer was evaluated by the ACI at the operating flow rate of 28.3 L/min.

Sample treatment procedures for the determination of mineral constituents in honey by Inductively Coupled Plasma Optical Emission Spectrometry

Preparative methods for quantification of inorganic constituents in honey by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) using microwave assisted digestion and ultrasonication procedures were developed. Analytical aspects such as matrix complexity, instrumental optimization and the essentiality/toxicity of the species K, Ca, Mg, Na, Fe, Mn, Zn, Cu, Co, Ni, Pb, Cd were considered. Parameters such as plasma power, nebulizer flow rate, torch configuration and the convenience of the use of yttrium as internal standard were evaluated. Recoveries between 93 and 107% (microwave digestion) and between 90 to 110% (ultrasonication procedure) and relative standard deviations lower than 10% were obtained. Samples of Brazilian honeys, from different parts of the country, were analysed and the results obtained provide relevant information about their mineral content.

Effect of the plasma operating frequency on the figures of merit of an inductively coupled plasma time-of-flight mass spectrometer

The analytical characteristics of a 27.12 MHz and a 40.68 MHz inductively coupled plasma time-of-flight mass spectrometer were evaluated under both hot and cool plasma conditions. The study was both direct and unambiguous because the same power supply, impedance-matching unit, load coil, and ICP torch were used at both operating frequencies. Although there are significant differences in the figures of merit between hot and cool plasma conditions, the performance at 27 MHz and 40 MHz was comparable. Under hot plasma conditions, measured ion energies and the plasma offset potential were nearly independent of the generator frequency. Higher ion energies and a greater plasma offset potential were apparent at 27 MHz under cold plasma conditions than at 40 MHz; however, this result may be an artifact of the difference in the optimal nebulizer flow rate rather than of frequency. Experimentally determined gas-kinetic and ionization temperatures did not demonstrate a significant frequency dependence.