Diethylenetriaminetetraacetic acid

This paper reports a new method for preconcentration and separation of trace amounts of molybdenum in seawater samples prior to determination by inductively coupled plasma-atomic emission spectroscopy (ICP-OES). Diethylenetriaminetetraacetic acid-functionalized polysiloxane (DETAP) was synthesized by carboxymethylation of amino groups on triamine immobilized polymer, which was prepared by modification of 3-chloropropylpolysiloxane with diethylenetriamine. The resulting polysiloxane is highly selective and efficient in chelating Mo(VI) at trace levels. It can be used as a column packing material. The polysiloxane column can be reused over ten times without losing its original properties, so it is suitable for preconcentration of molybdenum species in seawater samples before determination. The parameters governing the characteristics of polysiloxane for adsorption of Mo(VI) were investigated. These include the effect of pH, amount of polysiloxane, equilibrium time, adsorption isotherm, maximum adsorption capacity, interfering ions, flow rate, capacity for reuse, and desorption. The precision of the preconcentration method, calculated as the relative standard deviation of seawater samples, was 3%. The preconcentration factor was 100. The detection limit, defined as 3 times the standard deviation of five replicate measurements of the blank sample at pH 3, was 0.17 microg L(-1). Measurement results for standard reference materials were in good agreement with the certified values [(CRMs), NASS-2 Seawater (Open Ocean) and CASS-2 Seawater (Coastal)].

In this communication we describe a novel procedure for the preparation and purification of diethylenetriaminepentaacetic (DTPA)-acylated and (115)In(3+)-labeled oligopeptides using 8-hydroxyquinoline for the removal and quantification of nonbound indium ions. First the N(alpha)- or N(alpha),N(epsilon)-DTPA oligopeptides containing C-terminal KDEL signal motif were produced by solid-phase synthesis. For this the free carboxyl group of DTPA dianhydride was activated in situ for a short period of time yielding a major product. Reversed-phase HPLC-purified DTPA oligopeptides were labeled with (115)In(3+) in aqueous buffer solution at pH 3.8. For the removal as well as for the detection of uncoordinated (115)In(3+) ions we have utilized the (115)In(3+) complex-forming ability of 8-hydroxyquinoline in chloroform. Following an optimized extraction procedure the free indium ion content was measured by spectrophotometry in the organic phase. Data obtained by this method and verified by total-reflection X-ray fluorescence spectroscopy and thin-layer chromatography demonstrated that free (115)In(3+) could be efficiently removed and sensitively detected in the presence of DTPA oligopeptide chelator. No release of (115)In(3+) from its DTPA complex was observed. This method could be useful for the preparation of indium complexes of peptides and perhaps proteins containing a DTPA moiety and nonradioactive isotope ligand.

The environmental fate of ethylenediaminetetraacetic acid (EDTA) has been extensively studied, while much less is known about the environmental behaviour of diethylenetriaminepentaacetic acid (DTPA). In this study, it was confirmed that DTPA is persistent toward biodegradation. The biodegradability of DTPA was investigated in the absence and in the presence of Fe(III) by using CO2 evolution test and Manometric respirometry test. The CO2 evolution and oxygen uptake of iron-free (DTPA was added as free acid) and Fe(III)DTPA were less than in inoculum blank. Possible inhibitor effect was analysed by testing biodegradation of sodium benzoate with and without iron-free or Fe(III)DTPA in the Manometric respirometry test. Only slight inhibition was observed when DTPA was added as free acid. Photodegradation of iron-free DTPA and Fe(III)-DTPA complex was studied by using sunlight and UV radiation at the range 315-400 nm emitted by black light lamps. The results indicate that DTPA added as free acid degrades photochemically in humic lake water. Fe(III)DTPA was shown to be very photolabile in humic lake water in the summer; the photochemical half-life was below one hour. Photodegradation products were identified by the mass spectrometric technique (GC-MS). It was shown that photodegradation of Fe(III)DTPA does not result in total mineralization of the compound. Diethylenetriaminetetraacetic acid, diethylenetriaminetriacetic acid, ethylenediaminetriacetic acid, N,N'- and/or N,N-ethylenediaminediacetic acid, iminodiacetate, ethylenediaminemonoacetic acid and glycine were identified as photodegradation products of Fe(III)DTPA. Based on these observations, we propose a photodegradation pathway for Fe(III)DTPA.