Laser-enhanced ionization spectrometry

Travis, John C.; Turk, Gregory C.; Green, R. G.

doi:10.1021/ac00246a001

Cited by 122 publications

(56 citation statements)

References 28 publications

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“…1D) still shows, in spite of the absence of nitrogen in the atomization source, a structured spectral background of a different signature than that of NO (Fig. 1B), or of other molecular species such as O 2 , CO, CaOH and others that are usually found in analytical flames and are likely to generate a LEI signal [14] (the interference from CaOH, in particular, is a welldocumented LEI spectral background feature in the visible range [1]). Note that this structured background remains unchanged with or without the second excitation laserapart from a slight vertical displacement of the baseline upon addition of the second excitation laser, likely due to wing excitation of the potassium atomic states at 508.423, 509.717 and 509.920 nm-which suggests that only the first excitation laser is involved in the appearance of these spectral features.…”

Section: Resultsmentioning

confidence: 98%

“…Laser-enhanced ionization (LEI) is a highly sensitive detection technique for trace metals, based on the selective laser excitation of analyte atoms by pulsed tunable laser(s) to a high-lying excited state, followed by their collisioninduced ionization, usually in an air/acetylene flame where the samples have been vaporized and atomized [1,2]. The charges produced are then collected by an electric field applied across the flame and detected as a change in flame conductivity.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of hydroxyl-mediated spectral interference from easily ionized elements in laser-enhanced ionization spectrometry in the 281–285 nm range

Herreyre

Boudreau

2004

Spectrochimica Acta Part B: Atomic Spectroscopy

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Investigation of hydroxyl-mediated spectral interference from easily ionized elements in laser-enhanced ionization spectrometry in the 281–285 nm range

Herreyre

Boudreau

2004

Spectrochimica Acta Part B: Atomic Spectroscopy

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“…'76 The LEI technique utilized two pulsed lasers to perform a double-resonance electronic excitation of tin atoms in a premixed air-acetylene flame as the HPLC effluent stream entered the flame region. The resulting excited tin atoms undergo rapid collisional ionization, which is detected by electrodes in the 178 Laser-excited atomic fluorescence (LEAF) in an air-acetylene premixed flame was used for detection of organotins separated by HPLC on a Partisil SCX strong cation-exchange column, with a detection limit of 0.24 ng for a 20 pl inje~ti0n.I~~ HPLC was interfaced with a sodium borohydride (NaBH4) hydride generation system coupled to a quartz-tube firebrick-furnace atomic absorption spectrometer for speciation of Sn, MBT, DBT and TBT in methanolic solutions, using a Partisil SCX strong cation-exchange column with an eluent made of 50 mM citric acid, 50 mM LiOH and 4 mM oxalic acid in methanol.lS0 The limits of detection were 0.32 ng, 0.48 ng and 0.37 ng for TBT, DBT and MBT respectively, using a 100 p1 injection loop. The same arrangement has been used for speciation of methyltin and ethyltin compounds by normal-phase LC on an ODS Spherisorb S5W column with acetonepentane as eluent.…”

Section: Gc-fpdmentioning

confidence: 99%

Analytical Methods for Speciation of Organotins in the Environment

Attar¹

1996

Appl. Organometal. Chem.

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“…The dynamical range of LEI has been found to be up to four--to five--orders of magnitude both in flames and furnaces [6,16]. The upper limit is often set by a non-linear collection efficiency due to the large number of charges created.…”

Section: Detection Limits and Sensitivitiesmentioning

confidence: 99%

Analytical applications of laser-enhanced lonization spectrometry in flames and furnaces

1989

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This paper is concerned with a critical analysis of the analytical performance of laser-enhanced ionization (LEI) spectrometry in flames and furnaces as an ultra-sensitive trace-element technique. Updated tables of LEI detection limits, both in flames and furnaces, are given. Special attention is paid to interference phenomena which are unique to the LEI technique. Ways of reducing their influence on the analytical signals are proposed. Finally, advantages and disadvantages of LEI spectrometry as a tool for ultra-sensitive trace element analysis are discussed.Key words: laser-enhanced ionization (LEI), flame, furnace, trace element.Laser-enhanced ionization (LEI) spectrometry is a very powerful technique for detecting low concentrations of metal atoms in solutions I-1-23]. The major characteristics of the technique constitute of a high sensitivity and a rather high resistance to interferences. The general principle of the LEI technique is that an enhancement of the normal ionization processes (collisions) is obtained by optical excitation of the atoms under study by resonant laser light. The enhanced ionization rate is detected as a change in the current passing through a medium (atomic reservoir) exposed to a voltage by means of an electrode arrangement.When a sample is analyzed by LEI, the atomization can, in principle, be done in any of the conventional atomic reservoirs which previously have been developed for standard analytical techniques (absorption or emission techniques). However, LEI has so far most often been done in atmospheric pressure flames (primarily air/acetylene flames) and only recently LEI has been applied to graphite furnaces [8,16,17,[24][25][26].The atoms under study are excited from low lying, highly populated levels (primarily from the ground level) to high lying excited states by resonant laser light. Solution Boxcar Oscilloscope Fig. l. A typical experimental set-up for two-step LEI in flames. C = 10 nF and R = 50 k~This is almost exclusively done by using pulsed dye-laser systems for production of resonant laser light.Since the atomic reservoirs used for LEI are characterized by high temperatures in fairly dense media the collision rates between analyte atoms and buffer molecules are high. Hence, the atoms have certain probabilities of undergoing ionizing collisions. The probability of such collisional ionization is higher the less energy needed for ionization of the (excited) atoms. Therefore, the ionization probability increases the closer to the ionization limit the atoms are being excited [-27].The excitation of atoms in LEI spectrometry can be carried out in several ways. The most common excitation scheme is to excite the atoms from the ground state by absorption of one photon. By using ultra-violet light or by exciting the atoms in two consecutive steps a high ionization rate (efficiency) can be obtained. The two-step excitation is practically done by illuminating the atoms with light from two simultaneously pumped dye lasers, each tuned to a suitable transition wavelength in the...

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Laser-enhanced ionization spectrometry

Cited by 122 publications

References 28 publications

Investigation of hydroxyl-mediated spectral interference from easily ionized elements in laser-enhanced ionization spectrometry in the 281–285 nm range

Investigation of hydroxyl-mediated spectral interference from easily ionized elements in laser-enhanced ionization spectrometry in the 281–285 nm range

Analytical Methods for Speciation of Organotins in the Environment

Analytical applications of laser-enhanced lonization spectrometry in flames and furnaces

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