Determination of trace metals in waters and compost by on-line precipitation coupled to flame atomic absorption spectrophotometry or ion chromatography
ABSTRACT A general rapid on-line preconcentration method for the determination of trace metals coupled to flame atomic absorption spectrophotometry (FAAS) or ion chromatography (IC) with spectrophotometric detection is described. The method is based on the on-line precipitation of metal hydroxides with sodium hydroxide and their dissolution in a small volume of nitric acid solution. All the chemical and physical variables that affect the efficiency of metal precipitation and elution in the flow injection system have been studied. The detection limits obtained by FAAS are 0.1, 0.3, 0.5 and 0.5 μg l−1 for Zn, Cu, Ni and Pb, respectively. When the on-line precipitation is coupled to IC with post-column derivatization with the spectrophotometric reagent 4-(2-pyridylazo) resorcinol (PAR), the detection limits are 3, 1, 5, 3, and 3 μg l−1 for Cu, Zn, Ni, Co and Mn, respectively. The proposed general method was successfully applied to determine independently the above mentioned metals in compost and tap and river water samples.
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ABSTRACT: A simple method for multi-residue analysis of pesticides by low-pressure gas chromatography-tandem mass spectrometry (LP-GC-MS-MS) has been validated in compost samples. The pesticide residues were extracted from the lyophilised samples with organic solvent by stirring. No sample clean-up was required prior to the analysis. The method was applied to determine the fate of two organochlorine pesticides (lindane and endosulfan) and two organophosphates (malathion and chlorpyrifos-methyl) during the composting process in the reactor of a pilot plant. Malathion, chlorpyrifos-methyl and lindane residues almost fully disappeared after 8 days of maturation in the reactor, while endosulfan residues were only partially degraded. Alongside this, a study of natural disappearance of the pesticides was carried out in the laboratory and a characteristic time profile was traced for each pesticide class.Pest Management Science 06/2005; 61(5):458-66. · 2.59 Impact Factor
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ABSTRACT: The progress in flow‐injection (FI) on‐line separation and preconcentration employing knotted reactors (KRs) as a sorption medium for organometallic complexes associated to atomic spectrometry techniques is reviewed in this article, focusing the attention on the more frequently complexing agents used. In the last years, the KR has demonstrated to be an excellent alternative in the FI on‐line preconcentration procedures; the on‐line preconcentration and separation of different metallic species on the inner walls of the KR have been developed utilizing diverse organic and inorganic reagents. The choice of complexing reagents, the coupling of the FI preconcentration system to atomic spectrometry techniques, and the application of the methodologies developed to different samples are discussed.Applied Spectroscopy Reviews 01/2005; 40(1):71-101. · 2.92 Impact Factor
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ABSTRACT: A simple and sensitive method was developed for determination of trace copper by direct precipitation preconcentration and detection with Flame Atomic Absorption Spectrometry (FAAS). The reagent 2-[2'-(6-methyl-benzothiazolylazo)]-4-aminophenol (Me-BTAP) was used as precipitating agent. The experimental conditions for the quantitative precipitation of copper, such as pH, amount of reagents, temperature and the effect of diverse ions on the precipitation have been investigated. It was found that copper is quantitatively extracted (> or =95%) and the method provides a sensitivity enhancement of 40-fold for a 10 ml sample volume with a detection limit of 0.5 microg l(-1). The proposed method was successfully applied for the determination of trace copper in water, urine and biological samples.Environmental Monitoring and Assessment 02/2008; 148(1-4):245-53. · 1.59 Impact Factor