Application of Dispersive Liquid-Liquid Microextraction in Separation and Preconcentration of Silver prior its Determination by Flame Atomic Absorption Spectrometry

A simple, sensitive, and rapid dispersive liquid-liquid microextraction (DLLME) method is developed for the preconcentration of silver ions prior to determination by flame atomic absorption spectrometry (FAAS). In this work, 1-phenyl-1,2-propanedione-2-oximethiosemicarbazone (PPDOT), chloroform, and methanol are used as the complexing agent, extraction solvent, and disperser solvent, respectively. The effects of different analytical parameters on the complex formation and the extrac-tion efficiency are investigated and optimized. The effects of interfering ions on the determination of silver(I) are also examined. Under the optimized conditions, a linear calibration curve was achieved in the range of 0.60−120.0 µg L−1, with the detection limit of 0.61 µg L−1. The pre-concentration factor calculated as the ratio of the slopes of the calibration graphs with and without the pre-concentration was 35.5. The relative standard deviations (RSDs) for the silver(I) determinations were below 3 %. The proposed separation procedure was successfully applied to the determination of silver(I) in natural water and photographic film samples with satisfactory results (recoveries > 95 %)

A new and sensitive reaction rate method for spectrophotometric determination of trace amounts of thiourea in different water samples based on an induction period

BACKGROUNDAgrilus bigutattus (Fabricius) is a forest pest of increasing importance in the United Kingdom. The larvae damage weakened native oaks and are thought to contribute to premature tree death. Suspected links with acute oak decline (AOD) are not yet confirmed, but AOD-predisposed trees appear to become more susceptible to A. biguttatus attack. Thus, management may be necessary for control of this insect. To explore the possibility of monitoring beetle populations by baited traps, the host tree volatiles regulating A. biguttatus-oak interactions were studied. RESULTSBiologically active volatile organic compounds in dynamic headspace extracts of oak foliage and bark were identified initially by coupled gas chromatography-electroantennography (GC-EAG) and GC-mass spectrometry (GC-MS), and the structures were confirmed by GC coinjection with authentic compounds. Of two synthetic blends of these compounds comprising the active leaf volatiles, the simpler one containing three components evoked strongly positive behavioural responses in four-arm olfactometer tests with virgin females and males, although fresh leaf material was more efficient than the blend. The other blend, comprising a five-component mixture made up of bark volatiles, proved to be as behaviourally active for gravid females as bark tissue. CONCLUSIONSThese initial results on A. biguttatus chemical ecology reveal aspects of the role of attractive tree volatiles in the host-finding of beetles and underpin the development of semiochemically based surveillance strategies for this forest insect. (c) 2015 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry

Flow injection determination of ultra trace amounts of rhodium(III) with spectrophotometric detection

222-224A flow injection method for determination for rhodium (III) has been developed based on its catalytic effect on the oxidation of Nile Blue by periodate at pH 9.20. The react ion was monitored spectrophotometrically at 630 nm. The effects of reagent concentration and manifold variables were studied and optimized. The method is linear in the range of 0.030-30.0 μg.ml-1 Rh(III).The effects of interfering ions on the determination of Rh(III) have been studied. The proposed method has been used for the determination of rhodium(III) in synthetic samples with satisfactory results