Pulsed signal collection for laser-enhanced ionization spectrometry

Nippoldt, Mark A.; Green, Robert B.

doi:10.1021/ac00254a031

Cited by 14 publications

(6 citation statements)

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“…Various methods have thus been explored to eliminate this effect. Among them are, for instance, increase of voltage applied to the electrodes, 11,14,15 employment of pulsed voltage-biased collectors, 12,16 modification of electrode configuration, 8,11,14,15 pretreatment with a chromatographic method, 17,18 and acidification of the sample solution. 19 Recently, we developed an alternative to reduce the electrical interference by interfacing a flow injection (FI) system to the LEI apparatus.…”

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Laser-Enhanced Ionization Detection of Pb in Seawater by Flow Injection Analysis with On-Line Preconcentration and Separation

Lin

1999

Anal. Chem.

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The flame laser-enhanced ionization (LEI) technique is coupled with the flow injection analysis system to measure the trace lead amounts in aqueous solution and in seawater. The flow injection (FI) manifold is incorporated with a microcolumn packed with a C18 bonded silica. The chelating agent DDPA is used to form the Pb-DDPA complex, which may be sorbed in the microcolumn and then eluted with methanol. The preconcentrated Pb is then detected by the LEI technique with either single-step or two-step excitation. At 5- and 15-mL volume-fixed sample loading, the detection limits of 0.011 and 0.0033 ng/mL (11 and 3.3 ppt) and enrichment factors of 16 and 48 are achieved, respectively, using a two-step FI-LEI. The sensitivity of the current system proves to be better by at least 1 order of magnitude than that of conventional LEI method. The FI-LEI also increases the tolerance of matrix interference. The LEI signal is slightly reduced to 80% intensity as 10,000 micrograms/mL (ppm) Na and K matrixes are mixed in the lead solution. The resistance to the alkali matrixes is enhanced approximately 4 times that reported previously using a similar water-immersed probe as a LEI collector. Finally, the FI-LEI is for the first time applied to detect the Pb content in seawater, achieving a result of 0.0112 +/- 0.0006 ng/mL (ppb) consistent with the certified value of 0.013 +/- 0.005 ng/mL (ppb).

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“…Various methods have thus been explored to eliminate this effect. Among them are, for instance, increase of voltage applied to the electrodes, ,, employment of pulsed voltage-biased collectors, , modification of electrode configuration, ,,, pretreatment with a chromatographic method, , and acidification of the sample solution …”

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confidence: 99%

Laser-Enhanced Ionization Detection of Pb in Seawater by Flow Injection Analysis with On-Line Preconcentration and Separation

Lin

1999

Anal. Chem.

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“…ducibility in LEI detection. 54 In an effort to eliminate the electrical interference, we designed an apparatus by interfacing flow injection analysis (FIA) to the LEI device. In this way, the electrical interference was effectively reduced, and the linear dynamic range of sample concentration was much extended.…”

Section: A Technique To Diminlsh Electrical Interferencementioning

confidence: 99%

“…f ment, . improvement 0 e ectr e esign, mcrease 0 biased voltage,7.49.s2.~land employment of pulsed voltage-biased collectors 54. These current methods, although effective to diminish electrical interference, may somehow cause such side effects as disturbance of the flame structure.i" complication of the flame composition," or lack of repro-Indium concentration dependence in conventional LEI detection in a solution with varied Na concentration added as the matrix.…”

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Applications of Laser‐Enhanced Ionization In Analytical Chemistry

Lin

1994

J Chinese Chemical Soc

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Various applications of laser‐enhanced ionization (LEI) in analytical chemistry are reviewed. This technique was applied to determine some physical quantities associated with a flame through development of an appropriate model. Determinations of flame temperature and atomization efficiency of an element in the flame are examples. As trace analysis is an important application of this technique, we compare the ion yield induced in a two‐step LEI with that in a one‐step LEI. The factors governing the ion enhancement via two‐step excitation are examined in order to make efficient use of the two‐step LEI apparatus. A novel technique was designed to couple flow‐injection analysis to a conventional LEI device; in this manner, electrical interference, a severe problem inherent in LEI, was successfully removed.

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“…More recently, several treatments of signal collection in LEI spectrometry have been useful additions to the general theory (3,4). Investigators have reported interferences with LEI spectrometry in a series of papers (5)(6)(7)(8)(9)(10) 0003-2700/85/0357-0016$01.50/0 © 1984 American Chemical Society that identify and suggest ways of minimizing these effects. The performance of cylindrical (rod) and flat (plate) electrodes has been characterized and evaluated in several studies (5,6).…”

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confidence: 99%