Nebulizer background

Data for the several flame methods assume an acetylene-nitrous oxide flame residing on a 5- or 10-cm slot burner. The sample is nebulized into a spray chamber placed immediately ahead of the burner. Detection limits are quite dependent on instrument and operating variables, particularly the detector, the fuel and oxidant gases, the slit width, and the method used for background correction and data smoothing. 

For solution nebulization MC-ICPMS and MC-TIMS, typical runs consist of up to 100 ratios collected over 30 minutes to 1 hour. This includes time for background measurement (typically monitored at half mass on either side of the peak) and peak centering, but excludes filament warm-up time for TIMS and nebulizer cleaning for MC-ICPMS. Sample sizes of-1000-10 ng of total U for TIMS and MC-ICPMS are required to attain 2a measurement uncertainties of a permil or better on (e.g., Stirling et... 

Amselfelder red wine from Kosovo has been investigated with respect to uranium and plutonium content using ICP-SFMS (Element). The microconcentric nebulizer Aridus (Cetac Technologies) was applied for solution introduction into the ICP source. In different red wine samples, uranium with a natural isotopic composition was found at a concentration of 0.145 0.011 Jigl-1, which corresponds to the normal uranium background concentration. Plutonium was not detected at a detection limit of 10-5p,gl-1.36... 

ICP-MS is a multielement technique that is suitable for trace analysis it offers a long linear range and low background for most elements. ICP-MS is a technique where the ions produced in inductively coupled plasma are separated in a mass analyzer and detected. The sample solution is fed into a nebulizer by a peristaltic pump. The nebulizer converts the liquid sample into a fine aerosol that is transported into the plasma by an Ar gas flow. In the plasma the sample is evaporated, dissociated, atomized, and ionized to varying extents. The positive ions and molecular ions produced are extracted into the mass analyzer. Detailed descriptions of the ICP-MS technique can be found in a number of textbooks.13,14... 

Inductively Coupled Plasma. Analyses by ICP were performed on the same dissolutions used for the AA analyses for Cd and Pb. The solutions were diluted as necessary and were then nebulized and introduced into the plasma. Line spectra were collected with a multichannel analyzer and corrections were made for reagent blanks and background shifts. For all analyses, NBS Standard Reference Material 1632 was used for instrument calibration. 

Other methods have been developed for the removal of oxygen (particularly from flowing streams).These include the use of electrochemical or chemical (zinc) scrubbers, nitrogen-activated nebulizers, and chemical reduction (by addition of sodium sulfite or ascorbic acid). Alternately, it may be useful to employ voltammetric methods that are less prone to oxygen interference. The background-correction capability of modern (computerized) instruments is also effective for work in the presence of dissolved oxygen. 

Figure 15 ICP-MS background spectra (plotted on a logarithmic scale) for a sample containing 0.1% nitric acid (a) Conventional plasma conditions (1000 W, 0.77 L/min nebulizer gas flow rate). The Ar+ and 0+ signals are saturating the detector, so their signals are greater than 2 x 109 counts/sec. (b) Cold plasma conditions (600 W, 1.08 L/min nebulizer gas flow rate). Note that full scale in (a) is 10l° whereas in (b) it is 108. (From Ref. 147.)...

Attainable detection limits depend on the amount of analyte that enters the ICP per second, the efficiency of aerosol conversion into analyte ions in the ICP, and the transmission efficiency of ions from the plasma to the MS detector. The detection limits also depend on the variation of the background and the integration time. Typical pneumatic nebulizer/spray chamber systems operated at sample uptake rates from 0.1 to 2.0 mL/min introduce an amount of analyte equivalent to that in 10 to 30 JiL/min of sample solution into the ICP. At a sample uptake rate of 1 mL/min, only 1% to 2% of the analyte enters the plasma most of the sample is lost in the spray chamber and exits through the drain. Concentration based detection limits can be improved by approximately a factor of 10 by using a high-... 

An ultrasonic nebulizer (USN) has been found to be amenable to CE-ICP-MS interfacing [102]. The ground path was again provided by a sheath electrolyte, and separations were superior to those obtained by using a concentric nebulizer. It should be noted that the noisy background obtained by the USN may not give better detection limits than other nebulizers. 

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