EDTA-citrate complexing method

Ding X, Liu Y, Gao L, and Guo L. Synthesis and characterization of doped LaCrOs perovskite prepared by EDTA-citrate complexing method. J. Alloys Compounds 2007 458 346-350. 

Designed precursor) Hydroxide precursor Uniform precipitation, Sol gel method another precursor Cyanide decomposition. Oxalic Acid method, EDTA-citrate complexing method, Pechini method... 

Additives including anticoagulants such as citrate and fluoride can have large osmotic effects that cause water to shift from the cells to the plasma. This dilutes the lipoprotein by 10% or more and produces erroneously low values. EDTA, traditionally the preferred anticoagulant for lipoprotein measurements, causes a slight dilution, but has been used because it also inhibits certain oxidative and other changes that can affect some lipoprotein or apofipoprotein measurements. Lipid and Hpoprotein concentrations in EDTA plasma tend to be about 3% lower than in serum, an effect that may not be readily noticeable in HDL cholesterol measurements. EDTA, however, complexes some of the Mn in the heparin-Mn method, and it has been found necessary to use a higher concentration of MnCb (0.092 mol/L, final concentration in the reaction system) when the procedure is... 

Beryllium, Ga, Al, Fe(III), and V(IV) interfere in the determination of In as a complex with ECR and CTA. The influence of Zr, Th and U is smaller. Anions complexing indium, viz. EDTA, citrate and tartrate, must be absent. This method for determining indium becomes highly selective when indium is first separated as the iodide complex (see Section 24.2.1). 

A. Direct titration. The solution containing the metal ion to be determined is buffered to the desired pH (e.g. to PH = 10 with NH4-aq. NH3) and titrated directly with the standard EDTA solution. It may be necessary to prevent precipitation of the hydroxide of the metal (or a basic salt) by the addition of some auxiliary complexing agent, such as tartrate or citrate or triethanolamine. At the equivalence point the magnitude of the concentration of the metal ion being determined decreases abruptly. This is generally determined by the change in colour of a metal indicator or by amperometric, spectrophotometric, or potentiometric methods. 

The measurement of stability constants of complexes of yttrium, lanthanide, and actinide ions with oxalate, citrate, edta, and 1,2-diaminocyclohexanetetra-acetate ligands has revealed that there is a slight increase in the stability of complexes of the /-electron elements, relative to the others. A series of citric acid (H cit) complexes of the lanthanides have been investigated by ion-exchange methods and the species [Ln(H2cit)]", [Ln(H2cit)2] , [Ln-(Hcit)], and [Ln(Hcit))2] were detected. Simple and mixed complexes of dl- and jeso-tartaric acid have been obtained with La " and Nd ions, and the stability constants of lactate, pyruvate, and x-alaninate complexes of Eu and Am " in water have been determined. 

Two sulfide precipitation methods currently used are the soluble sulfide precipitation (SSP) and insoluble sulfide precipitation (ISP) processes. Soluble sulfides and insoluble sulfides are used to precipitate dissolved metals as metal sulfides. Metal sulfides have lower solubilities than the hydroxides, resulting in lower residual metal concentrations in the treated water (Figure 1). Also, sulfides can be used to precipitate complexed metals in the presence of complexing agents such as ammonia, citrate and EDTA and over a broader pH range than possible for the hydroxide precipitation.3 A typical sulfide precipitation reaction is as follows ... 

The main interfering metals in the copper determination are Fe, Bi, Mn, Ni, Co, Cr, Mo and U, which form coloured complexes. The selectivity of the method is considerably enhanced by the use of EDTA as a masking agent. In a tartrate or citrate medium at pH 8-9, Fe, Mn, Ni and Co are masked by EDTA, as are Cd, Pb, Zn, and In, which form colourless complexes with DDTC. Of the metals forming coloured compounds with DDTC, only Bi, Tl(III), and Cu are not masked. Thallium, when reduced to T1(I), does not interfere. Bismuth can be stripped from the organic extract, containing copper and bismuth diethyidithiocarbamates, with 5 M HCl. Copper diethyidithiocarbamate is decomposed by cyanide, whereas the bismuth complex remains unaffected. 

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