Determination of seven trace elements in natural waters after separation by solvent extraction and anion-exchange chromatography

A method is described for the determination of cadmium, cobalt, copper, manganese, lead, uranium, and zinc in samples of natural waters. After acidification with hydrochloric acid the water sample is filtered and the diethyldithiocarbamates of the trace elements are isolated by extraction with acetone—chloroform (2:5) at pH 5. Following this preconcentration step the metal ions are adsorbed on a column of the strongly basic anion-exchange resin Dowex 1-X8 (chloride form) using as sorption solution a mixture (5:4:1, $\text{v}\text{v}$) of tetrahydrofuran, methyl glycol and 6 M hydrochloric acid. Successive elution is effected with 6 M hydrochloric acid (Co, Cu, Mn and Pb), 1 M hydrochloric acid (U) and 2 M nitric acid (Cd and Zn); the metal ions in the eluates are determined by atomic absorption spectrophotometry (except uranium, which is determined fluorimetrically). The procedure was used to determine the trace-metals in water and snow samples collected in Austria and to analyse a sample of sea water from the Adriatic Sea.     

Analytical applications of azoisoxazoles. III. Complexes of cobalt,copper, and cadmium with 2-(5′-methyl-2′-isoxazolylazo)-4-methoxyphenol

2-(5′-methyl-2′-isoxazolylazo)-4-Methoxyphenol has been synthesized and its ionization constant (pK_a = 7.98 ± 0.08) spectrophotometrically determined in a 4% ($\text{v}\text{v}$) ethanol-water medium at μ = 0.25 M (NaClO₄). The reagent originates water soluble complexes with cobalt (log β₂ = 11.45 ± 0.16), copper (log β₁ = 7.15 ± 0.10), and cadmium (log β₁ = 3.96 ± 0.12), and can be used for the spectrophotometric determination of cobalt and copper as well as metallochromic indicator for copper.     

Anodic stripping determination of mercury in air with a glassy carbon electrode

A technique for stripping determination of mercury traces in air employing a glassy carbon electrode is described. The sample is passed at 2 liters min^?1 for 2 hr through an absorber containing 0.2 M potassium permanganate and 10% $\text{w}\text{v}$ sulfuric acid (1:1). After reduction with hydroxylamine hydrochloride, the determination is carried out in 0.12 M potassium thiocyanate at pH 2.0 ± 0.2 in the presence of 0.2 ppm of cupric ions. Calibration curves were found to be linear in the range 20 ppb-1 ppm Hg(II) in the cell. The accuracy of the method was tested over simulated samples and it was found to be better than 95%; the relative standard deviation was 5% or less. The limit of detection of mercury in air was approximately 10 μg m^?3.     

Anwendung von ionenaustauschverfahren zur bestimmung von spurenelementen in natürlichen wässern—V: Blei

A method is described which makes possible the separation of lead from natural waters at the ppM level, and its final determination by spectrophotometry or atomic absorption. The sample is made 0.15M in hydrobromic acid, filtered, and passed through Dowex 1 X8 (bromide form). The lead is sorbed on the resin and most of the other elements present are separated from it. The lead is eluted with 6M hydrochloric acid and determined by the dithizone method or by atomic-absorption. The method was used to determine lead in drinking water and water from the Danube, lead concentrations in the range 2–14 ppM being found.     

Determination of thallium and lead in cadmium salts by anodic stripping voltammetry with addition of surfactants to suppress the cadmium peaks

Conditions have been found which make possible the determination of thallium and/or lead in cadmium and its salts without preliminary separation. The electrochemical activity of the cadmium, which usually interferes in the determination of thallium, is inhibited by the addition of 0.01% of polyethylene glycol of M.W. 4000. Thallium is determined by electrolysis at ?0.74 V vs. SCE, in 0.1M EDTA solution: 10^?1M thallium can be determined in the presence of 0.1M cadmium, while copper and lead at 10^?2M and 10^?5M respectively do not interfere. Lead is determined in 0.1M acetic acid containing 0.1% cetyltrimethylammonium bromide (CTAB). The addition of CTAB shifts the cadmium peak, as well as the optimum deposition potential for cadmium, to more negative values, making it possible to determine lead in the presence of cadmium as long as the deposition potential lies in the range between ?0.50 and ?0.56 V vs. SCE. Lead can be determined in the presence of ten times as much thallium.     

Determination of traces of antimony and tin in copper by anodic stripping voltammetry

The determination of antimony and tin impurities in copper by anodic stripping voltammetry on a hanging mercury drop electrode is described. Antimony and tin were previously separated from copper by distillation with hydrobromic acid or a mixture of hydrobromic acid and hydrochloric acid. The method was applied to the analysis of various high-purity copper samples, commercially available, showing satisfactory sensitivity and precision. The determination limit was about 1.4· 10^-9M for antimony and 7·10^-10M for tin in solution, for pre-electrolysis times of respectively 15 and 25 min; this corresponds to 0.8 p.p.b. of antimony and 0.3 p.p.b. of tin for a 2-g sample and a final volume of 10 ml after separation.     

On the sign of the dipole moment derivatives in CH3X (X = F, Cl, Br, I)

It is shown in this paper that the principal methods for reducing the indeterminacy of the sign of (δ M/δ$\text{O}$_i) (isotropic invariance of M, quantum mechanical calculations, determination of (δM/δ$\text{O}$_i) via high resolution data or the Stark effect) lead, in the case of CH₃X (X = F, Cl, Br, I) molecules, to contradictory conclusions. The discrepancies are illustrated and discussed. It is also pointed out that either a revision of the previous results or a calculation of electro-optical parameters on a set of chemically similar molecules including CH₃X could possibly lead to a unique determination of the sign.     

Halogen catalyzed acetylenic oxy-cope rearrangement in N-methyl-2-pyrrolidone solvent a new industrial process for pseudoionone and its analogues

Selective synthesis of pseudoionone was achieved by the acetylenic oxy-Cope rearrangement of 4-isopropenyl-3,7-dimethyl-6-octen-1-yn-3-ol ($\text{3}$) in N-methyl-2-pyrrolidone solvent containing a trace of hydrochloric acid, hydrobromic acid, iodine, ammonium bromide and ammonium chloride catalysts.     

Spectrophotometric determination of phosphate by extraction of reduced molybdoantimonylphosphoric acid with acetophenone-chloroform

A 90% ($\text{v}\text{v}$) mixture of acetophenone-chloroform is an effective extractant for reduced molybdoantimonylphosphoric acid. The extraction is quantitative over the acidity range of 0.04 to 4.8 N sulfuric acid. The mixed solvent extractant is virtually immiscible with water and can be used at aqueous/organic volume ratios from 1:1 to 40:1 with no loss of solvent or decrease in % extraction. Phosphate is easily determined from 5 to 1000 ppb. No interference from silicate was experienced.     

Dependence of polymer specific volume on molecular characteristics

Linear and branched bisphenol A polycarbonate (PC) samples were characterized by their average molecular weights, $\text{M}{}_{\mathrm{<mtext>n</mtext>}}$ and $\text{M}{}_{\mathrm{<mtext>w</mtext>}}$, polydispersity degree $\text{q =}\text{M}{}_{\mathrm{<mtext>w</mtext>}}\text{/}\text{M}{}_{\mathrm{<mtext>n</mtext>}}$, and branching degree g_v. The weight fraction of microgel was also determined for branched samples. The samples were amorphized and densities were measured at 23°C to obtain the values of specific volume, v_sp. The dependence of v_sp on molecular characteristics is described by the multivariable power function $\text{Δv}{}_{\mathrm{<mtext>sp</mtext>}}\text{=}\text{A}{}_{\mathrm{sp}}\text{M}{}_{\mathrm{<mtext>x</mtext>}}{}^{\mathrm{<mtext>a</mtext>}}\text{q}{}^{\mathrm{<mtext>apx</mtext>}}\text{g}{}_{\mathrm{<mtext>v</mtext>}}{}^{\mathrm{<mtext>ab</mtext>}}$, where Δv_sp = v_sp ? v_sp,∞, and A_sp, a, a_px and a_b are constants. It has been confirmed that a = ?1, a_pn = 0 and a_pw = 1. It has also been found that the branching exponent a_b significantly depends on microgel content. The relationships found for PC should, in principle, be valid for other polymers. Examples based on literature data are given for linear polyethylene and polydimethylsiloxane.     

Application of gel permeation chromatography and viscometry for characterization of branched polydisperse polycarbonate

Gel permeation chromatography (GPC) and viscometry (V) methods have been combined for determination of long-chain branching in bisphenol-A polycarbonate (PC) by means of a branching factor $\text{g}{}_{\mathrm{v}}\text{=}\text{M}{}_{\mathrm{vg}}{}^1\text{/}\text{M}{}_{\mathrm{v}}{}^1$, where $\text{M}{}_{\mathrm{vg}}{}^1$ and $\text{M}{}_{\mathrm{v}}{}^1$ are the apparent viscosity-average molecular weights calculated from GPC data and from intrinsic viscosities [η] of the samples respectively. A linear dependence of g_v on molar % of branching agent has been obtained. The GPC data on PC samples have also been applied for verification of an earlier [η]?M relationship for branched polydisperse polymers.     

High frequency titrations involving chelation with ethylenediaminetetra-acetic acid. II. quantitative determination of some divalent metals

The high frequency oscillator provides an excellent means of detecting the end-points of titrations performed with ethylenediaminetetraacetic acid or its salts. The determination of various divalent metals is reported, based on both direct and indirect titrations. Because of the great sensitivity of the method it is possible to determine cobalt, nickel, copper (II), zinc, cadmium, lead and manganese (II) in concentration ranges of 1/1000 to 1/6000M.     

Preparation of cadmium orthoplumbate at normal pressure by decomposition of the respective coprecipitated carbonates

The thermal decomposition of lead and cadmium coprecipitated carbonates was found to be a good method for the preparation of cadmium orthoplumbate.By heating carbonates coprecipitated in the molar ratio Pb/Cd = $\text{1}\text{2}$, at 500–525°C, in an oxygen stream at normal pressure, it is possible to prepare an almost pure cadmium orthoplumbate.The X-ray diffractogram of the orthoplumbate prepared in this way coincides almost exactly with that diffractogram given in the literature, both with regard to the interplanar spacing (d) and the relative intensities, I/I₁. However, the line 1.971 Å ($\text{I}\text{I}{}_1$ = 33) does not appear in the diagram given in the literature, whereas this line is repeated in all the samples studied by us.     

Chemical analysis of mixtures of some heavy metals by means of differential reaction rates of ligand substitution reactions

The simultaneous determination of some heavy metals in their mixtures is described. The method is based on the differential reaction rate of ligand substitution reactions involving ethyleneglycol bis(2-aminoethylether)N,N,N',N'-tetraacetic acid (EGTA) and 4-(2-pyridylazo)-resorcinol (PAR). Various combinations at the 10^-6M level of heavy metal ions such as manganese(II), iron(III), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), mercury(II) and lead(II) can be determined photometrically.     

Preferential energy transfer from N2(A) to specific energy levels of Cu atoms

Emission spectra resulting from reaction of “clean” N₂(A³ Σ_u⁺) with copper atoms were studied using a flowing afterglow apparatus. The population distribution of the Cu states was calculated from the spectrum; it indicates that Cu atoms are excited by nearly resonant energy transfer processes. N₂(A,v') + Cu(²S_{$\text{1}\text{2}$}) → N₂(X, v) + Cu^* , and that the transfer is most efficient for N₂(A,v') → N₂(X,v) transitions with large Franck-Condon factors. The preferential energy transfer results in population inversion between some of the Cu states.     

Determination of Cadmium(ii), Copper(ii), Mercury(ii), and Lead(ii) in Water Using Stochastic Sensors Based on Graphite and Diamond Paste Modified with 1H-Pyrrole-1-Hexanoic Acid

Graphite/diamond pastes modified with 1H-pyrrole-1-hexanoic acid were used for the design of stochastic sensors. The proposed stochastic sensors were used to determine four heavy metals, copper(II), cadmium(II), mercury(II), and lead(II), in water samples. The sensitivities of the stochastic sensors were high for all four metal ions, and their limits of determination were sufficiently low to enable detection at very minute concentrations; in some cases, unreachable using standard methods of analysis. The recoveries of copper(II), cadmium(II), mercury(II), and lead(II) in water samples were higher than 93.00%, with relative standard deviation values lower than 1.00%. The sensors were used to simultaneously determine copper(II), cadmium(II), mercury(II), and lead(II) in water samples. The obtained results were in agreement with those obtained using standard analytical methods.     

The optimization of an ICP injection technique and the application to the direct analysis of small-volume serum samples

The optimization and the analytical properties of an injection technique for the analysis of small-volume samples (50–200 μl) by inductively coupled plasma atomic emission spectroscopy (ICP-AES) are described. Samples are injected into a small funnel connected to a concentric glass nebulizer. A 3 kW argon/nitrogen ICP with power stabilization is used as excitation source. When operating the nebulizer at an argon pressure of 5 bar, relative detection limits for calcium, copper, iron, magnesium and zinc (0.2–50 $\text{ng}\text{ml}$) are a factor of 2 to 10 higher when compared with ICP methods using continuous nebulization. However, the full power of detection of the injection method is obtained at a 50 μl sampling volume. Matrix effects caused by sodium salt concentrations of 5 $\text{g}\text{l}$ are lower than 10%. Relative standard deviations s_r,(I_X) ranged from 0.03 to 0.07. The method was applied to the sequential determination of trace elements (copper, iron and magnesium) in human serum samples after a 1 + 4 dilution with Herrmann solution. The accuracy of the method is illustrated by the analysis results for calcium, copper, iron, magnesium and zinc in a series of test serum samples.     

Crystallographic studies on cation substitutions in the system (Na,K) (V,P)O3

Three compounds in the system (Na,K) (V,P)O₃ were synthesized and their structures were refined by full matrix least squares method in the space group $\text{C2}\text{c}$. Their compositions were shown by site population analysis to be Na(V_0.66P_0.34)O₃ (I), (Na_0.88K_0.12)VO₃ (II), and (Na_0.5K_0.5)VO₃ (III). All are related to the structure of α-NaVO₃ which in turn is related to the clinopyroxene structure characterized by infinite chains of SiO₄ tetrahedra sharing vertices and two inequivalent metal cation sites M1 and M2. Both sites feature sixfold coordination in compounds I and II, while the Na and K are ordered into M1 and M2 sites, respectively in III, with the latter showing eightfold coordination. The pentavalent cations are randomly distributed in tetrahedral sites in I, and in II the K was found to occupy the M2 sites only. Changes in the α-NaVO₃ structure upon cation substitution are discussed in terms of rotation and displacement of the tetrahedral chains. Parameters for measuring these chain movements are proposed and found to exhibit an almost linear relationship with the ratio $\text{〈X?0〉}\text{〈M2?0〉}$ in cases where the M1 site is exclusively occupied by Na.     

Sine-wave polarographic determination of small amounts of indium in the presence of large amounts of cadmium,lead or tin

The sine-wave polarographic determination of small amounts of indium in the presence of large amounts of cadmium, lead or tin was investigated. The determination of indium in cadmium was possible down to 0.01 % in 1 M potassium iodide at pH 2, the determination of indium in lead was possible down to 0.02 % in 1 M potassium chloride at pH 2, and the determination of indium in tin was possible down to 0.3 % in 1 M hydrochloric acid and down to 0.2 % in 2 M perchloric acid with 0.5 M sodium chloride.