ABSTRACT
A procedure is developed for determination of As, Co, Se, Cr, Pb, Zn, Cu, Mn, Cd, Sb, and Sn in water by ICP-AES analysis of alcohol eluates after pre-concentration of the samples. The pre-concentration is performed on a sodium diethyldithiocarbamate supported soft polyurethane foam. The sorbed elements are subsequently eluted with 1-propanol and the alcohol eluates are analysed by ICP-AES. A eight-fold concentration is achieved. An increased sensitivity in the analysis of propanol-water (30:70, v/v) solution is established as compared with aqueous solutions. The strongest effect is observed for As, Se, Pb, Cr, Sn, and Cd-increasing is more than twice. For other elements the matrix influence is by a factor of 1.45 (Cu), 1.36 (Sb), 2.08 (Zn). The method is applied to the analysis of natural water samples.
ABSTRACT
Sodium diethyldithiocarbamate in the presence of a weak oxidizing agent is used as a co-precipitative agent for the pre-concentration of Se, Cu, Pb, Zn, Fe, Co, Ni, Mn, Cr and Cd. A procedure was developed for ICP-AES determination of these elements after pre-concentration in river and waste water (an enrichment factor of 40). The recovery of all the elements tested for was more than 98%. The limits of determination (mg l(-1)) (10 S.D. blank) are 0.001 (Cu, Co, Cr, Mn), 0.0007 (Zn, Cd), 0.003 (Se), 0.004 (Fe), 0.007 (Ni), and 0.01 (Pb).
ABSTRACT
A new masking agent in complexometry, beta-dithiocarbaminopropionic acid (beta-DTCPA) is proposed. beta-DTCPA forms very stable water-soluble complexes with a number of metal ions. Zinc can be titrated selectively with EDTA at pH 5-6 in the presence of large amounts of cadmium, which is masked effectively as a cadmium-beta-DTCPA complex. Correct results have been obtained with Cd/Zn ratios up to 300: 1.
ABSTRACT
Dithiocarbaminoacetic acid (TCA) is proposed as an effective masking agent in the dithizone extraction determination of zinc in the presence of lead, cadmium and cobalt(II). The extraction equilibrium is treated quantitatively by means of two approaches: the "conditional distribution coefficient" and the computer program HAL-TAFALL. Both methods give similar results and enable the most suitable conditions for the separation and determination of zinc in the presence of the other ions to be determined. A successful attempt is made to predict the maximum permissible quantity of interfering elements. The experimental check, performed under various conditions, is in satisfactory agreement with the theory.
ABSTRACT
The stability constants of lead, cadmium and zinc dithio-carbaminoacetic acid (TCA) complexes have been determined. Lead and cadmium TCA complexes were studied by means of a polarographic method. A competitive polarographic method was used for the study of zinc TCA complexes. Zinc and cadmium TCA complexes were also studied potentiometrically with an amalgam electrode. The stability constants found were: lead, log beta(2) = 13.2; cadmium, log beta(1) = 5.4 (pot.), log beta(2) = 9.3 (pot.), log beta(3) = 13.7 (pot.), 13.6 (pol.); zinc, logbeta(1) = 3.4(pot.), <3.8(pol.), logbeta(2) = 6.6 (pot.), 6.4(pol.), logbeta(3) = 8.9 (pot.), 9.3 (pol.).
ABSTRACT
Dithiocarbaminoacetic acid (TCA) forms very stable, water soluble complexes with a number of metal ions and is a suitable masking agent in complexometry. TCA masks from EDTA and complexometric indicators at pH 2-6 the following elements: bismuth(III), indium(III), thallium(III), cadmium(II), lead(II), mercury(II) and copper(II), thus making possible the complexometric determination of other elements in their presence.
