Alpha/beta indices determination in drinking water using plastic scintillation and evaporation to dryness

Alpha/beta indices are screening parameters that provide a quick approach to the determination of the radioactivity levels of water samples. These indices have commonly been determined by methods involving measurement by proportional counter or liquid scintillation (LS) techniques. However, both of these types of techniques present some limitations. Plastic scintillation (PS) is an alternative technique that does not generate mixed wastes and also provides a solid surface onto which the sample can be evaporated. The objective of this study is to evaluate a new procedure for the determination of alpha/beta indices using PS microspheres and evaporation to dryness. For this purpose, the capabilities of this technique were first compared with those of LS and PS in solution. Various parameters were then optimised: the diameter of the microspheres, the discrimination values and the evaporation system. Next, the calibration procedure was established, and finally, the procedure was validated with the analysis of spiked water samples. The results show that this technique can be applied for alpha/beta indices determination with a simple procedure, high detection efficiency and acceptable uncertainties.     

Application of ultra performance liquid chromatography-tandem mass spectrometry to the analysis of priority pesticides in groundwater

Ultra performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UPLC-MS/MS) has been applied for the accurate and rapid analysis of nine trace level priority pesticides in water. The UPLC technology, based on the use of columns packed with 1.7 microm porous particles combined with higher pressures than those conventionally applied in HPLC, enabled to improve in peak resolution, sensitivity and speed of analysis. UPLC chromatograms showed very sharp peaks with less than 2 s wide at the base, except for alachlor. This enhanced efficiency resulted in an increased separation speed of the whole UPLC-MS/MS procedure that required less than 5 min. Limits of detection, determined for 300 ml water samples after SPE preconcentration were in the range between 0.1 and 20 ng/L. The presence of matrix effects or ion suppression was checked by the obtaining of calibration curves in both pure solvent and matrix matched standards. Other performance characteristics of the method, such as linearity and precision were also satisfactory. Finally, the method was successfully applied to the analysis of two water samples from an inter-laboratory exercise.     

Donor-acceptor interaction promoted gelation: visual observation of color change

An anthrylidene derivative of arjunolic acid could immobilize varieties of organic solvents at low concentrations in the presence of an electron-deficient guest. Gelation in the presence of picric acid in organic solvents could be observed visually with concomitant color change. Electron micrographs of the xerogels showed a fibrous structure having fibers of submicron diameters. [structure: see text].     

Calculation of electric dipole intensity parameter to explore some interaction between hard metal ions Pr(III) and Nd(III) with pi-electron density of butene-1,4 and butyne-1,4-diols in non-aqueous solutions: an absorption spectral study

Pr(III) and Nd(III) are hard acceptors in HSAB (hard and soft acid base) sense and hence are known to exhibit practically a little affinity towards electrons. At the same time these metal ions show strong preference for oxygen donor chelating ligands. The ligands chosen for this study are structurally related diols, viz. butane-1,4, butene-1,4 and butyne-1,4-diols which form identical seven membered chelate ring by coordinating to metals in a bidentate manner through oxygen on 1 and 4 positions of the diol molecules. Complexation of these diols with Pr(III) and Nd(III) was carried out in DMF, CH3OH, CH3CN and their equimolar binary mixtures using comparative absorption spectrophotometry of 4f-4f transitions. The variation of oscillator strengths (P) of different 4f-4f bands as well as the magnitude and variation of Judd-Ofelt electric dipole intensity parameters (T lambda, lambda = 2, 4, 6) was discussed. They correlate the interaction between the metal 4f-orbitals of Pr(III) and Nd(III) with the pi-electron densities of the double and triple bonds present in butene-1,4 and butyne-1,4-diols, respectively. The value of empirical intensity parameter [T lambda(complex)/T lambda (aquo)] was calculated and its plot against oscillator strength (P) is drawn.     

Phosphorus-supported multidentate coumarin-containing fluorescence sensors for Cu

Phosphorus hydrazides PhP(O)[N(Me)NH₂]₂, (S)P[N(Me)NH₂]₃, and N₃P₃[N(Me)NH₂]₆ were condensed with 7-diethylaminocoumarin-3-aldehyde (RCHO) to afford the corresponding hydrazones PhP(O)[N(Me)NCHR]₂ (1), (S)P[N(Me)NCHR]₃ (2), and N₃P₃[N(Me)NCHR]₆ (3). The structural characterization of 1-3 was carried out by their HRMS, ¹H and ³¹P{¹H} NMR spectra. The molecular structure of 2 was established by a single-crystal X-ray analysis. Interaction of 1 and 2 with various transition metal ions revealed substantial fluorescence enhancement upon interaction with Cu²⁺ enabling a selective detection mechanism for this metal ion. However, such a fluorescence enhancement was not observed in the case of 3. A 1:1 complex [2·Zn][ClO₄]₂·4CH₂Cl₂ was isolated in the reaction of 2 with Zn(ClO₄)₂·6H₂O. The molecular structure of this complex revealed that the Zn^II is encapsulated by the ligand utilizing a 3N, 3O coordination set.     

Development and evaluation of a plastic scintillating resin for radioactive tin determination

Journal of Radioanalytical and Nuclear Chemistry - In the next few years, a large number of nuclear facilities will be closed. This will involve the measurement of large amounts of nuclear wastes...