Walenty Szczepaniak

Spectrophotometric determination of trace amounts of lead(II) by ion-pair extraction with cryptand (2.2.2) and eosin

Abstract The solvent extraction of ion-pair complexes of calcium, strontium and lead (2.2.2) cryptates is described. The extraction equilibrium constants ( D C , K ex and K D ) at room temperature are reported. The formation of the positively-charged lead cryptate ion and its extraction into chlorobenzene as an ion-pair with eosin are the basis of the proposed spectrophotometric determination of traces of lead. The high molar absorptivity of the ion-pair complex (ϵ = 1.1 × 10 5 l mol -1 cm -1 ) and the linearity of the calibration graph over the range 0–10 -5 M, allow even 0.1 ppm lead to be determined. The selectivity is high; there is no interference from cations often occurring with lead, such as Bi 3+ , Sn 2+ , Hg 2+ , Zn 2+ , Cd 2+ , Cu 2+ , Ca 2+ , Pd 2+ , Ag + and Tl + .

Liquid-state mercury(II) ion-selective electrode based on N-(O,O-diisopropylthiophosphoryl)thiobenzamide

Abstract A liquid ion-exchange electrode containing a complex of mercury(II) with N -(O,O-diisopropylthiophosphoryl)thiobenzamide in carbon tetrachloride is described. The electrode shows excellent sensitivity and good selectivity. The slope of the calibration graph is 29.0 mV/pHg 2+ in the pHg 2+ in the pHg 2+ range 2–15.2 in mercury(II) ion buffers. The electrode can be used for determination of 5 × 10 −5 –10 −2 M Hg(II) in the presence of 10 −2 M Cu(II), Ni(II), Co(II), Zn(II), Pb(II), Cd(II), Mn(II), Fe(III), Cr(III), Bi(III) or Al(III) ions and in the presence of 10 −3 M Ag(I) ions. It can bealso used for end-point detection in titrations with EDTA of 10 −3 –10 −4 M mercury(II) at pH 2.

Specific adsorption of halogen anions on hydrous γ-Al2O3

Abstract The paper reports results of a study on the specific adsorption of F−, Cl−, Br−, I−, ClO3−, BrO3−, IO3− and IO4− on hydrous γ-Al2O3. The isotherms of the anion adsorption and the adsorption dependencies on pH and the ionic strength of the solution have been determined under the equilibrium conditions. According to the degree of affinity to γ-Al2O3, the anions can be ordered as: I−

Extraction studies of metal complexes with some macrocyclic tetraaza ligands and xanthene dyes : Spectrophotometric determination of Cadmium(II) with Tetramethyltetraazacyclotetradecane and Erythrosin A

Abstract The liquid-liquid extraction of ion-pair complexes of zinc(II), copper(II) and cadmium(II) is described. The macrocyclic ligands 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (4Me-cyclam-14) and rac-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (Tet b) are used with xanthene dyes as the counter ions. The apparent extraction constants (D′c) are reported. The sequences of extraction efficiency of both ligands are related to the structure of the complexes. The apparent molar absorptivity of the Cd(4Me-cyclam-14)—erythrosin A ion-associate is 1.1 × 105 l mol− cm−1. The calibration graph is linear over the range 0—10−5 M, which allows even 0.05 μg ml−1 cadmium to be determined in a 0.5 M sodium hydroxide medium. No interference was observed from Ni2+, Pb2+, Zn2+, Mg2+, Sn4+, Ga3+, Al3+ and Fe3+. Interferences were Cu2+, Hg2+, Ag+ and large anions.

Voltammetric determination of Prometrine in soil and water

Abstract A sensitive adsorptive stripping differential pulse voltammetric method was proposed for the determination of Prometrine in soil and water. The voltammetric response was evaluated with respect to a few electrolyte solutions, the accumulation time and potential, and the concentration dependence. The relationship between i p and Prometrine concentration was linear in the range 1 × 10 −8 –11 × 10 −7 M Prometrine. Conditions for soil and water sample preparation were established. The relative standard deviation is 6.5% for 5 determinations of Prometrine in water and 3.1% for 5 determinations of Prometrine in soil.

Study of a Landolt-type reaction with ascorbic acid in a vesicular system by means of the quenching effect of iodine

Abstract The iodine quenching effect on the fluorescence of the binaphthyl-based amphiphile C 8 BNC 6 N, was applied to the monitoring of a Landolt-type reaction between hydrogen peroxide, potassium iodide and ascorbic acid. The vesicular system presented takes advantage of both the extremely high sensitivity of iodine detection (10 −8 M level) and the micellar “concentration effect” which permits the indicator reaction to be monitored at very low concentrations of substrates. Significant differences are observed compared with the conventional Landolt reaction: first, the optimum pH range is shifted towards higher pH values (pH 4–6), and second a strong concentration effect is observed for negatively charged ions which allows the sensitive determination of catalysts and substrates. A very sensitive method for the determination of ascorbic acid at levels down to 10 ng ml −1 is proposed. The usefulness of the method was evaluated by the determination of ascorbic acid in food and body fluid samples.

Lanthanide complex formation with a hexaaza macrocyclic ligand, 1,4,7,10,13,16-hexaazacyclooctadecane (A618-Crown-6)

Stability constants of lanthanide complexes with 1,4,7,10,13,16-hexaazacyclooctadecane (A618C6) in aqueous 0.1 M NaC1 medium have been determined at 20 °C by an out-of-cell potentiometric titration method. Lanthanide complexes with A618C6 are more stable than those of the macrocyclic polyethers and bicyclic cryptands. No appreciable metal ion specificity is observed, but with increasing atomic number of the lanthanides, the stability increases similarly to that observed for diazapolyoxa-macrocycles. The unusually high stability of the lanthanide A618C6 complexes is discussed in terms of the formation of partial bonds between the lanthanide ion and nitrogen donors and the inertness of the Ln-hexaaza-18-membered system.

Determination of trace amounts of impurities in pharmaceutical preparations by differential-pulse polarography: Part 1. Determination of diisooctyl maleate in the pharmaceutical sodium 1,4-bis(2-ethylhexyl)sulphosuccinate and of maleic acid in fumaric acid

Abstract A differential-pulse polarographic procedure is described for the determination of impurities such as diisooctyl maleate and maleic acid in pharmaceutical products. The concentration range for diisooctyl maleate is 1 × 10 −6 −30 × 10 −6 μg ml −1 and the detection limit is 0.2 μg ml −1 ; for maleic acid the detection limit is 0.15 μg ml −1 . It is possible to determine very low concentrations of maleic acid in the presence of fumaric acid by a preseparation by dissolution in water, in which fumaric acid dissolves to only a small extent.

Extraction-spectrophotometric determination of lead in heavy metal salts with cryptand (2.2.2) and eosin

A rapid, extraction-spectrophotometric determination of trace amounts of lead in heavy metal salts is proposed. Owing to application of ammonia as masking agent, the extraction system cryptand (2.2.2)-eosin-chlorobenzene exhibits very high selectivity towards transition metal cations. Using standard addition method, lead is determined without matrix separation in nitrates, chlorides, acetates and sulphates of such metals as Ag, Cd, Ni, Cu and Zn. The effect of matrix on lead extraction efficiency and blank value is also discussed. The high sensitivity and selectivity of the proposed method allow to determine of lead at the level 10−3−10−4%.

Binaphthyl-based fluorescent amphiphiles for analytical systems based on energy transfer

New binaphthyl-based amphiphiles with malonate, dioxocyclam and polyethylene glycol head groups were synthesized and characterized. Vesicles and lamella-type aggregates were observed in aqueous dispersions. The aggregation behaviour and spectral characteristics are discussed in terms of the structure and charge of the head groups of the amphiphiles. A concept of analytical exploitation of fluorescent amphiphiles is presented, where the «sensing pseudo-phase» consists of acceptor molecules incorporated in donor amphiphile aggregates. Perylene (Per), perylene tetracarboxylate (PTC), Auramine O (AuO) and the heavy metal cation Cu 2+ were tested as acceptors or quenchers