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A method was developed for the quantitative analysis for calcium and magnesium in sodium–matrix waters using capillary electrophoresis with indirect detection. Separation of the divalent metals from the matrix ion was investigated via addition of a weak diacid in the electrolyte. The optimum separation conditions were chosen after simulations of the migration times of the cations at pH 5.0 and were experimentally tested. Among the selected diacids, oxalic acid and tartaric acid gave the best peak-to-peak resolution for all the cations. The cationic chromophore was selected from a series of weak bases. Optimisation of the sensitivity for the alkaline–earth metals was investigated via alteration of the electrolyte pH to adjust the mobility of the chromophore to those of the cations. The best analytical conditions were obtained with 10 mM creatinine/2mM oxalic acid, pH=4.6 and 14.4 mM benzylamine/8 mM tartaric acid, pH=4.8. System peaks were sometimes present in the potassium and sodium regions but did not interfere with the quantitative treatment. Limits of detection of 4 μM were achieved in a simulated matrix containing 500 ppm of sodium, whcih corresponds to the upper limit for the matrix–ion concentration. The proposed method was applied to the determination of calcium and magnesium ions in saline underground waters.

Time-resolved laser-induced fluorescence (TRLIF) is a method of choice for actinides and lanthanides determination at low level in nuclear, biological and environmental samples. This technique is based on pulsed laser excitation followed by temporal resolution of the fluorescence signal. This technique has many advantages such as: high sensitivity, rapidity, triple selectivity and is applicable in a wide range of activity concentrations. TRLIF has been used in several fields such as; geology, in the PUREX process, in the medical field, in the environments and for nuclear waste disposal applications. Trends are towards the use of TRLIF for remote determination via fiber optics and optode as well a speciation.

Fast and direct determination of uranium in zirconium is required for nuclear process control. Time-resolved laser-induced fluorescence spectrometry is a very selective and sensitive method that has been largely used for uranium(VI) analysis in the nuclear fuel cycle. Due to the very low quenching constant of zirconium, the uranyl fluorescence signal is weakly affected by this element. By using direct fluorescence signal measurement, the uranium concentration is obtained in less than a minute and the limit of detection is close to 10 ng 1 −1 which corresponds to 1 ng g −1 relative to the zirconium matrix. Moreover, the zirconium dissolution medium (nitric/hydrofluoric acid) is complexing enough to allow direct measurement with no use of other complexing reagent. Such procedure can also be used for uranium determination in hafnium.

The aim of this work is the development of an on-line analytical procedure for uranyl trace determination in the nuclear fuel reprocessing process using time-resolved laser-induced fluorescence. Because the uranyl fluorescence spectrum is strongly affected by the nitrate concentration, knowledge of composition of the medium is necessary to normalize measurements. This paper reports the assumptions made on the spectral distortion, leading to a spectral deconvolution model. Uranyl complex formation constants are obtained from the spectral deconvolution and validate the method. In this way, spectral distortion allows the determination of the nitrate concentration with good accuracy.

Complexation studies of radionuclides (such as uranium) are important to perform in order to predict their migration behavior in natural systems. Time-resolved laser-induced fluorescence, which is a very selective and sensitive method for actinide and lanthanide analysis, is used to study the interactions between uranyl cation and hydroxide ions at low uranium concentration (0.4 [mu]M). The principle of the study is based on time resolution and spectral convolution since free uranyl ion (UO[sub 2][sup 2+]) and first hydroxide complex give specific fluorescence spectra characterized by their spectral shift and fluorescence lifetime. Spectroscopic data (main fluorescence wavelengths, half-bandwidth, lifetime) for the first hydrolyzed complex UO[sub 2]OH[sup +] are obtained. From experimental spectra and time-resolved spectral convolution, the proportion of each species (free uranyl, complexed uranyl) can be estimated at different pH. 33 refs., 5 figs., 3 tabs.

Les techniques de spectroscopie laser sont de plus en plus employees pour l'analyse elementaire a bas niveau et la speciation des actinides et autres radionucleides d'interet. A partir d'une recherche bibliographique et des experiences developpees au sein du Laboratoire de spectroscopie laser analytique, le principe, les performances, les applications ainsi que les avantages et les inconvenients de ces differentes techniques laser sont presentes, une comparaison est effectuee avec une autre technique (non-laser) analytique performante, la torche a plasma – spectrometrie de masse. Les differentes techniques laser presentees sont en spectroscopie moleculaire : la lentille thermique, la spectrofluorimetrie laser a resolution temporelle, la fluorescence induite par laser de l'iode, et en spectroscopie atomique : la spectroscopie optogalvanique, la fluorescence induite par laser en four de graphite, la fluorescence induite par laser dans une torche a plasma, la spectroscopie d'ionisation resonnante colineaire et l'ionisation laser couplee a la spectrometrie de masse. Les principaux avantages des techniques de spectroscopie laser sont l'absence de preparation d'echantillon, la rapidite, la selectivite, la sensibilite ainsi que la possibilite de pouvoir effectuer des analyses a distance via fibre optique.

A comparison between nitrogen and tripled Nd-YAG laser source for Time-Resolved Laser- Induced Fluorescence (TRLIF) of uranium in nitric acid solutions in the framework of on-line feasibility has been performed. Hence, for uranium on-line monitoring with fiber optics, nitrogen laser (337 nm), most usual source in TRLIF has several drawback; poor beam quality and non negligible nitric acid absorption at 337 nm. Tripled Nd-YAG laser (355 nm) despite lower uranium absorption coefficient has several advantages: no influence of nitric acid absorption, better beam quality, better fiber transmission and solid state technology. No significant difference for fluorescence spectra and lifetimes are observed for both lasers. Limit of detection for direct determination of uranium in nitric acid by TRLIF is in the μ/l (10−8 M) range for both lasers.

Time-resolved laser-induced spectrofluorimetry was used for the determination of uranium at the ng 1 −1 level in alkaline water with high chloride and sulphide contents in order to obtain a better understanding of uranium mobilization under natural reducing conditions. The optimum complexing medium, limit of detection and results obtained for several waters from different localities in the Pyrenees are presented. These data seem to confirm that even at very low uranium concentrations, thermodynamic control by a mineral phase takes place.

The determination of uranium as a toxic (chemically and radioactively) element in human urine is of major medical interest since metabolic models must be established in order to estimate the body burden of uranium in professionally exposed workers. Moreover, nuclear medical regulations require important controls of uranium, with levels determined, from workers' urine samples. Different methods have been and are still used to perform such measurements, namely: fluorescence on pellets, chromatography, counting techniques, neutron activation, and mass spectrometry. However, these different techniques are time consuming, and some of them require bulky equipment. Laser-Induced Time-Resolved Spectrofluorometry (LITRS) is a very sensitive technique for ultratrace determinations of uranium in solution and seemed appropriate for these analyses. This technique is based on laser excitation followed by temporal resolution of the fluorescence signal. The great advantages of this technique, aside from sensitivity, are its triple resolution (i.e., excitation, emission, and life-time) and its rapidity.

Time-Resolved Laser-Induced Fluorescence (TRLIF) is a very sensitive and selective method that has been used for actinides and lanthanides analysis in the nuclear fuel cycle. This technique has been used in different fields such as in geology, in the Purex process, in the environment, in the medical and in waste storage assessment. Spectroscopic data, limits of detection and results obtained in previously quoted fields are presented.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Time-Resolved Laser-Induced Fluorescence has been used for uranium and nitrate remote sensing in the nuclear fuel cycle. Advantages of this technique are aside sensitivity and selectivity, its ability to perform remote measurements via fiber optics and optode. Uranium is usually determined by the standard addition method but by applying a fluorescence model taking into account complexation and absorption phenomena, it is possible to directly determine uranium concentration. Nitrate concentration is determined after spectral deconvolution of the uranium fluorescence spectrum.

Time-Resolved Laser-Induced Fluorescence (TRLIF) is a very sensitive and selective method that has been used for actinides and lanthanides analysis in the nuclear fuel cycle. This technique has been used in different fields such as in geology, in the Purex process, in the environment, in the medical and in waste storage assessment. Spectroscopic data, limits of detection and results obtained in previously quoted fields are presented.

Time Resolved Laser-Induced Spectrofluorometry (TRLIS) is a ve sensitive and ?' selective method that has been used for actinides and lanthanides analysis in the nuc ear fuel cycle. This technique has been used in different fields such as in geology, in the Purex process, in the environment, in the medical and in waste storage assessment. Spectroscopic data (A excitation, X emission, lifetime), limits of detection and results obtained in previously quoted fields are presented.

The most convenient spectral regions for dye laser excitation are presented for seven lanthanide ions. Fluorescence lifetimes are given for 0.5 M sulphuric acid and 3 M potassium carbonate media. With the excimer-pumped dye laser, the detection limits are in the range 0.1 μg 1−1 (Eu) to 50 μg 1−1 (Gd). Examples of the resolution of mixtures are given.

This paper describes a new procedure for the direct determination of uranium in plutonium solutions using time-resolved spectrofluorometry. The analytical method is based upon the use of sulfuric acid as a dilution medium and leads to a detection limit of U/Pu = 0.2 ppm. A formula taking into account both quenching and inner-filter effects is presented. It permits the calculation of the detection limit or uranium in complex solutions and could be used to obtain a theoretical limit of detection for similar applications.