The Design and Some Emission Characteristics of an Economical dc Arc Plasmajet Excitation Source for Solution Analysis

1970 ◽  
Vol 24 (2) ◽  
pp. 197-205 ◽  
Author(s):  
S. E. Valente ◽  
W. G. Schrenk
Keyword(s):  
Gas Flow ◽  
Matrix Effects ◽  
Detection Limits ◽  
Inert Gas ◽  
Excitation Source ◽  
Analytical Response ◽  
Gas Consumption ◽  
Moderate Sensitivity ◽  
Dc Arc ◽  
Better Than

The de-arc plasmajet has been applied to a large number of emission problems since its introduction in 1959 because it offers reduced matrix effects, stability, and moderate sensitivity. However, its use has been significantly limited due to operating costs associated with its high inert gas flow rates. A new excitation source, based on the principle of the plasma jet, has been developed that can operate at a much lower cost. The source operates from a conventional dc-arc power supply and uses commercially available electrodes. Total inert gas consumption is less than 2.5 liters/min. Stability of the source is better than 1% and reproducibility is approximately 4%. An excitation temperature of 5800 K was calculated from the relative intensities of several vanadium lines. The source can be operated continuously for several hours at a time. Design and some characteristics of the arc are presented. Detection limits are given for 12 elements. Six of the elements (Ca, Cr, Fe, Li, Ni, and Y) have detection limits below 10 ng/ml. Analytical response for the elements studied is linear over a wide concentration range. A calibration curve for Ca is presented which is linear over more than four orders of magnitude.

Atomic Fluorescence Spectrometry with a Graphite Rod Atomizer and Thermostated Electrodeless Discharge Lamps

1973 ◽  
Vol 27 (3) ◽  
pp. 171-176 ◽  
Author(s):  
B. M. Patel ◽  
R. D. Reeves ◽  
R. F. Browner ◽  
C. J. Molnar ◽  
J. D. Winefordner
Keyword(s):  
Gas Flow ◽  
Detection Limits ◽  
Sample Volume ◽  
Atomic Fluorescence Spectrometry ◽  
Fluorescence Signal ◽  
Electrodeless Discharge ◽  
Atomic Fluorescence ◽  
Flow Rates ◽  
Graphite Rod ◽  
Better Than

Atomic fluorescence investigations with a graphite rod atomizer and thermostated multiple element electrodeless discharge lamps (EDL's) are reported for Ag, Cd, Cu, Hg, Pb, Sn, Tl, and Zn. Detection limits in the range 10−10 to 10−14 g have been obtained for these elements using a sample volume of 0.5 µl. The detection limits are better than, or close to, the lowest reported values obtained by other workers using atomic spectrometric methods. No spectral or chemical interferences have been observed when using multiple element EDL's or standard multielement solutions. The atomic fluorescence signal obtained using argon and argon-hydrogen atmospheres has been studied as a function of the gas flow rates and as a function of height above the graphite rod atomizer. Except for Hg, better fluorescence signals are obtained with argon-hydrogen.

scholarly journals REDUCING THE DETECTION LIMITS OF SPECTROMETER WITH NITROGEN MICROWAVE PLASMA «GRAND-SVCH»

2020 ◽  
Vol 8 (1) ◽  
pp. 108-117
Author(s):  
Oleg V. Komin ◽  
Oleg V. Pelipasov
Keyword(s):  
Excitation Energy ◽  
Flow Rate ◽  
Gas Flow ◽  
Microwave Plasma ◽  
Detection Limits ◽  
Spectral Lines ◽  
Excitation Source ◽  
Gas Flow Rate ◽  
Excitation Energies ◽  
Varying Parameters

The article presents the results of a study of the effect of the power supplied to the microwave plasma and the nebulizer gas flow rate on the detection limits of the spectrometer with nitrogen microwave plasma «Grand-SVCH». It is shown that a change of the spectral lines intensity of the elements being determined with varying parameters of the spectra excitation source is related to their excitation energy. The maximum intensities of the lines are achieved at a power of 1700 W and a nebulizer gas flow of 0,4 l/min and 0,6 l/min for lines with excitation energies of 4-15 eV and 3,5-4 eV, respectively. Using the obtained values of the parameters of the excitation source of the spectra allows reducing the detection limits of elements by 1,5-4 times.

Evaluation of the Microwave-Induced Plasma for Multielement Emission Spectrometric Analyses

1976 ◽  
Vol 30 (5) ◽  
pp. 504-507 ◽  
Author(s):  
R. K. Skogerboe ◽  
G. N. Coleman
Keyword(s):  
Standard Method ◽  
Matrix Effects ◽  
Internal Standard ◽  
Argon Plasma ◽  
Excitation Source ◽  
Internal Standard Method ◽  
Microwave Induced Plasma ◽  
Detection Capabilities ◽  
Composite Samples ◽  
Better Than

A microwave-induced argon plasma has been evaluated as a spectrochemical excitation source for multielement analyses of solutions. Results for 12 elements indicate that detection capabilities are typically better than 0.01 µg/ml. Analyses of food composite samples indicate that matrix effects occur but these are cancelled by the use of the internal standard method.

Spectra for Gaseous Halogens with the dc Arc and Inert Gas Shields

1972 ◽  
Vol 26 (5) ◽  
pp. 527-530 ◽  
Author(s):  
W. A. Loseke ◽  
E. L. Grove
Keyword(s):  
Inert Gas ◽  
Tungsten Electrodes ◽  
Thoriated Tungsten ◽  
Atomic Lines ◽  
Dc Arc

The spectra for the halogens were excited in a Stallwood jet using a dc arc between 1% thoriated tungsten electrodes. The shield gases were helium, 50% argon-50% helium, and argon. In helium, only atomic lines of fluorine were excited, some singly ionized lines of chlorine were excited, and the atomic lines of iodine were weak. Atomic lines of fluorine were faintly visible in argon while the atomic lines of chlorine, bromine, and iodine showed an increasing intensity in 50% argon-50% helium, and argon, respectively.

Matrix effects using an ICP-MS with a single positive ion lens and grounded stop: analyte mass dependent?

2017 ◽  
Vol 32 (5) ◽  
pp. 951-966 ◽  
Author(s):  
John W. Olesik ◽  
Shi Jiao
Keyword(s):  
Gas Flow ◽  
Matrix Effects ◽  
Mass Matrix ◽  
Gas Flow Rate ◽  
Icp Ms ◽  
Single Positive ◽  
Mass Dependent ◽  
Positive Ion ◽  
Comprehensive Characterization

Comprehensive characterization of ICP-MS matrix effects as a function of analyte mass, matrix mass, lens voltage and nebulizer gas flow rate was carried out.

Effect of Inert Gas Flow Nature on SiC Microtube Synthesis

2005 ◽  
pp. 220-225 ◽  
Author(s):  
Jae Won Kim ◽  
Seoung Soo Lee ◽  
Dong Ho Park ◽  
Yeon Gil Jung ◽  
Je Hyun Lee ◽  
...  
Keyword(s):  
Gas Flow ◽  
Inert Gas

Analysis of gas flow over a cylinder at all Knudsen numbers based on non-newtonian constitutive models

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040076
Author(s):  
Zhen-Yu Yuan ◽  
Zhong-Zheng Jiang ◽  
Wen-Wen Zhao ◽  
Wei-Fang Chen
Keyword(s):  
Constitutive Model ◽  
Gas Flow ◽  
Constitutive Relations ◽  
Constitutive Models ◽  
Direct Simulation Monte Carlo ◽  
Navier Stokes ◽  
Dsmc Simulation ◽  
Nonequilibrium Flows ◽  
Simulation Results ◽  
Better Than

This paper is focused on the gas properties over a cylinder from continuum to rarefied regimes based on the non-Newtonian constitutive model. This new constitutive model is first derived from Eu’s nonequilibrium ensemble method, which is intended for accurate description of nonequilibrium flows. Some assumptions and simplifications are made during the establishing progress of the new constitutive model by both Eu and Myong. To verify its accuracy, temperature contours and skin frictions around the cylinder are simulated by this new model. The inflow Mach number is equal to 10 and the Knudsen number ranges from 0.002 to 0.05. All simulation results are compared with Navier–Stokes (NS) and the direct simulation Monte Carlo (DSMC) methods in detail. The comparisons of friction around the surface show that the non-Newtonian constitutive models are better than the linear constitutive relations of NS equations for the prediction of nonequilibrium flow and much more close to DSMC simulation results.

Analysis of Pesticide Residues by Chemical Derivatization. VI. Analysis of Ten Acid Herbicides in Sediment1

1983 ◽  
Vol 66 (4) ◽  
pp. 1023-1028
Author(s):  
Hing-Biu Lee ◽  
Alfred S Y Chau
Keyword(s):  
Sediment Sample ◽  
Detection Limits ◽  
Chemical Derivatization ◽  
Multiresidue Analysis ◽  
Organic Extract ◽  
Sediment Samples ◽  
Routine Monitoring ◽  
Liquid Chromatographic ◽  
Acid Herbicides ◽  
Better Than

Abstract A sensitive gas-liquid chromatographic (GLC) method was developed for multiresidue analysis of 10 acid herbicides in sediment. An acidified sediment sample was extracted 3 times with acetonehexane. The combined organic extract was partitioned with acidified water to remove aqueous coextractives. To produce low detection limits for all herbicides including MCPA and MCPB for routine monitoring purposes, pentaf luorobenzyl esters were formed before GLC analysis. Recoveries of all herbicides from fortified sediment samples were better than 80% at the levels studied. Practical detection limits of this method were 10-25 μg/kg (ppb).

Semi-Solid Slurry Casting Using Gas Induced Semi-Solid Technique to Enhance the Microstructural Characteristics of Al-4.3Cu Alloy

2019 ◽  
Vol 285 ◽  
pp. 253-258
Author(s):  
M. Abdi ◽  
S.G. Shabestari
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Temperature Drop ◽  
Inert Gas ◽  
Globular Structure ◽  
Cast Sample ◽  
A206 Alloy ◽  
Gas Purging ◽  
Semi Solid ◽  
Conventionally Cast

Semi-solid processing of Al-4.3%Cu (A206) alloy was performed by Gas Induced Semi-Solid (GISS) process in different condition. The flow rate of argon gas, starting temperature for gas purging (the temperature of superheated-melt) and the duration of gas purging were three key process variables which were changed during this investigation. It was found that inert gas purging near liquidus, significantly, led to the microstructural modification from fully dendritic to globular structure. Thermal analysis was successfully implemented through CA-CCTA technique to understand the cause of the microstructure change during GISS process. The results showed that gas purging into the melt leads to temperature drop of the melt to its liquidus just after a few seconds from start of gas purging. In fact, copious nucleation was induced by cooling effect of inert gas bubbles. Microstructural features were characterized in semi-solid as well as on conventionally cast samples. The optimum gas purging temperature, injection time, and inert gas flow rate was determined in semi-solid processing to obtain the best globularity in the microstructure of a long freezing range alloy. However, the microstructure of the conventionally cast sample was fully dendritic with shrinkage which affects the soundness of casting products.

Respiratory and inert gas exchange during high-frequency ventilation

1982 ◽  
Vol 52 (3) ◽  
pp. 683-689 ◽  
Author(s):  
H. T. Robertson ◽  
R. L. Coffey ◽  
T. A. Standaert ◽  
W. E. Truog
Keyword(s):  
Gas Exchange ◽  
High Frequency ◽  
Gas Flow ◽  
Inert Gases ◽  
Inert Gas ◽  
High Frequency Ventilation ◽  
Physiological Dead Space ◽  
Volume Ventilation ◽  
Frequency Ventilation ◽  
Carrier Gases

Pulmonary gas exchange during high-frequency low-tidal volume ventilation (HFV) (10 Hz, 4.8 ml/kg) was compared with conventional ventilation (CV) and an identical inspired fresh gas flow in pentobarbital-anesthetized dogs. Comparing respiratory and infused inert gas exchange (Wagner et al., J. Appl. Physiol. 36: 585--599, 1974) during HFV and CV, the efficiency of oxygenation was not different, but the Bohr physiological dead space ratio was greater on HFV (61.5 +/- 2.2% vs. 50.6 +/- 1.4%). However, the elimination of the most soluble inert gas (acetone) was markedly enhanced by HFV. The increased elimination of the soluble infused inert gases during HFV compared with CV may be related to the extensive intraregional gas mixing that allows the conducting airways to serve as a capacitance for the soluble inert gases. Comparing as exchange during HFV with three different density carrier gases (He, N2, and Ar), the efficiency of elimination of Co2 or the intravenously infused inert gases was greatest with He-O2. However, the alveolar-arterial partial pressure difference for O2 on He-O2 exceeded that on N2-O2 by 5.4 Torr during HFV. The finding agrees with similar observations during CV, suggesting that this aspect of gas exchange is not substantially altered by HFV.

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