Determination of extraction constants for metal diethyldithiocarbamates and chloride-mixed metal diethyldithiocarbamates by substoichiometric extraction

Abstract

A new method was developed for simultaneous determination of extraction constants of simple metal dethyldihiocarbamates, M( DDC), and chloride-mixed metal diethyldithiocarbamates, M( DDC),-,CI, by substoichiometric extraction incorporated with radlometry. The extraction constants of simple metal diethyldlthlocarbamates, KM(Dm), for M = Hg( II), Bi( H I ) , Cd(II), As(", and Fe(I1) obtained In this work are in good agreement with those in the literature. The extraction constants of the chloride-mixed metal diethyldithiocarbamates, K~D m ) , _ , c , , for M = Hg(II), BI(III), Cd(II), and As(II1) are reported for the first time.Diethyldithiocarbamate (DDC) is a powerful ligand to chelate many metal ions (1). Extraction constants of various metal diethyldithiocarbamates differ over several decade orders of magnitude (2). The values of the extraction constants are of great importance in predicting the feasibility of separating selectively a single metal or a group of metals by choosing a proper metal diethyldithiocarbamate as extraction reagent (3)(4)(5)(6)(7)(8). So far very little information on the extraction constants has been obtained, although the qualitative extraction order for a variety of metals under specified conditions has been investigated by several authors (6,(9)(10)(11)(12)(13). General schemes for the determination of extraction constants were summarized by Stary and Kratzer (13). Likussar and Boltz used the maximum of the continuous variations plot in terms of normalized absorbance to determine the extraction constants (14, 15). However, these methods are difficult to apply to complexes with relatively high extraction constants as is the case with so many metal diethyldithiocarbamates.In 1968, Ruzicka and Stary introduced the substoichiometric extraction method (16). Since then, the method has been extensively used in analytical work (4,7,9,17,18). The characteristic feature of the method is that the quantity of extractant is adjusted appropriately so as to extract only partial amounts of the metal or metals of interest. The method would become simple and highly selective if a radiotracer technique were incorporated. Wyttenbach and Bajo first applied the substoichiometric extraction method to determine the extraction order of metal diethyldithiocarbamates (9). In their study, successive substoichiometric increments of reagent were used to extract mixtures of two metal elements in 0.1 N H2S04 medium, and then the extraction order was established by comparison of the extraction curves obtained by plotting the extracted fractions vs. amounts of diethyldithiocarbamates added. No quantitative values of extraction constants were obtained in their study.In the present work, a new method was described for quantitative determination of the extraction constants of metal diethyldithiocarbamates by using substoichiometric extraction Present address, Institute of Nuclear Energy Research, Lungtan, Taiwan 325, Republic of China.incorporated with radiometric technique. When the substoichiometric extraction is appli...

Quantum Chemical Approach for Calculating Stability Constants of Mercury Complexes

“…Another example is complexation of Hg 2+ with diethyldithiocarbamate (Dtc), which was detected in Suwanee River natural organic matter using ultrahigh resolution mass spectrometry . Although various two-phase solvent extraction constants − were reported for [Hg­(Dtc) 2 ] 0 , the computed aqueous stability constant in eq agrees most closely with the experimental log K value (33.35) that was measured by competitive ligand exchange followed by C18 solid-phase extraction …”

Extraction of arsenic(III) and arsenic(V) from natural waters for neutron activation analysis

“…The earliest analyses of opium in a forensic context were done by using spot tests and thin-layer chromatography (10).…”

Rotating Disk Sorptive Extraction of Cu-Bisdiethyldithiocarbamate Complex from Water and Its Application to Solid Phase Spectrophotometric Quantification

“…The reaction between copper and sodium diethyldithiocarbamate has been used in the determination of copper in diverse matrices. [13][14][15][16][17] The complex formed in ammoniacal media is the yellow complex copper(II) bisdiethyldithiocarbamate. Despite the reaction of a number of other metal ions with DDTC, the determination is selective for copper mainly because the absorption band of the copper complex does not overlap the absorption bands of other metal-DDTC complexes.…”

“…Carlos MUÑOZ,* M. Inés TORAL,** Inés AHUMADA,* and Pablo RICHTER* † Diethyldithiocarbamate (DDTC) is an organic reagent widely used in analytical determinations of trace metals. [13][14][15][16][17] When DDTC reacts with copper, the complex Cu(DDTC)2 is formed, which is an uncharged complex with a square-planar geometry that can be extracted into PDMS due to the absence of charge. The main advantage of this new method over existing methodologies is that it is the only one that achieves very low detection limits for determination of copper in water without using organic solvents in the sample preparation process.…”

“…Accordingly, a concentration of 1 × 10 -3 M DDTC was sufficient for the analytical determination of copper in the absence of other possible interferences. However, it is well known that, under certain conditions, trace elements such as Co, Cd, Ni, Fe, and Zn can react with DDTC, thereby consuming part of the reagent, 16,24 despite the fact that their complexes absorb at wavelengths different from that of the copper complex. Consequently, we opted to use the reagent at a higher concentration of 0.1 mol L -1 to ensure complete formation of the copper complex in real samples (Table 1).…”