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Analytical and Bioanalytical Chemistry (v.362, #3)
Analytical methodologies for chromium speciation in solid matrices: a survey of literature by M. J. Marqués; A. Salvador; A. E. Morales-Rubio; M. de la Guardia (pp. 239-248).
The analytical literature about chromium speciation in solid samples has been surveyed. From 451 articles published on the speciation of chromium from 1983 to 1997, the methodologies to do speciation in solids after sample pretreatment are discussed, through consideration of the types of samples and their dissolution, the analytical techniques employed for chromium measurement, and the figures of merit of the 86 papers reported in the Analytical Abstracts data base.
Pressure dependence of secondary ion emission from selected 3d, 4d, and 5d transition metals under N2O, NO, and NO2 by W. Rybczynski; W. Seidel; H. D. von Zerssen (pp. 249-253).
The reactant gas pressure dependence of secondary ion emission from surfaces of polycrystalline Cr, Fe, Co, Mo, Rh, W, Re, and Ir under the action of N2O, NO and NO2 was observed by means of moderate dynamic SIMS. The mass spectra for constant reactant gas pressure indicate the existence of two different groups of transition metals showing either dissociative or partial molecular adsorption behavior. This is confirmed at least above some suitable reactant gas pressure. Besides some special details (Fe/NO; Co/NO) several of the relative secondary ion intensities vs. reactant gas pressure exhibit similar curvature as for O2, thus indicating the NOx gases to be modified sources of oxygen. At higher pressures molecular secondary ions with and without metal atoms come to be appreciable.
A convenient and practical procedure to derive correction factors to estimate atomic ratios by XPS by T. Nakamura; Atsushi Ogata; Takahiro Hoshi; Retsu Oiwa (pp. 254-257).
In quantitative XPS, the preparation of reference samples is difficult or impossible, and the correction factor method has been employed. Therefore, a convenient and practical procedure to get correction factors to estimate atomic ratios is proposed, in which it is assumed that the XPS intensity distribution corresponds to the distribution of the photoionization cross section. This procedure can be applied to some instruments and various samples without the previous collection, preparation of reference sample groups, and determination of sensitivity factors for each element.
Dynamic adsorption and desorption of heavy metal ions on poly(acrylaminophosphonic-carboxyl-hydrazide) chelating fiber by R. Liu; Baowen Zhang; Hongxiao Tang (pp. 258-262).
The dynamic adsorption and desorption properties, including the effect of pH value and flow rate on the adsorption, eluent acidity and volume, eluting velocity and re-use, of Cu(II), Pb(II), Zn(II), Cd(II), Mn(II), Ni(II), Co(II) and Hg(II) ions on the column loaded with poly(acrylaminophosphonic-carboxyl-hydrazide) chelating fiber were investigated. The recovery of Mn(II), Co(II), Cd(II), Ni(II) and Zn(II) ions in the presence of Na, K, Ca and Mg ions was examined. The preconcentration of trace amounts of Mn(II), Co(II), Cd(II), Ni(II) and Zn(II) ions from model solution samples was carried out with satisfactory results. The amount of the metal ions detected after preconcentration and recovery by this technique was basically in agreement with the added amount. The method is rapid, precise and simple.
Redox-potentiometric/titrimetric analysis of aqueous iodine solutions by Waldemar Gottardi (pp. 263-269).
Redox-potential, titrimetric oxidation capacity and pH were used to analyze aqueous iodine solutions over a concentration range of five decades. By a single operation the equilibrium concentrations of I–, I2, I3 –, I5 –, I6 2–, HOI and OI– were assessed. Accuracy was most influenced by the redox-potential showing a repeatability of < ± 0.1 mV in solutions containing appreciable iodide (Lugol’s solution) which increased to ±1.5 mV at a 1:100 000 dilution. Together with the uncertainty of calibration this equals a calculated total error which ranges for “free iodine” ([I2] + [HOI]), from ± 0.5% to ± 4.2% and for total iodide from ± 0.7 to ± 5.3%. Accuracy was assessed by a comparison of the evaluated equilibrium concentrations and parameters derived therefrom, such as total iodide and redox-potential, with measured resp. calculated values. The deviations at ionic strength < 0.1 M were below ± 3% and revealed a satisfactory accuracy of the method. As a unique feature it was possible to monitor the disproportionation in a iodide-free iodine solution with an initial concentration of 16% hypoiodic acid (HOI) at pH 7.6. Showing a half-life time of only ≈ 75 s it was confirmed that stability largely depends on HOI concentration.
Analytical reliability of carbonyl compound determination using 1,5-dansylhydrazine-derivatization by N. Binding; Holger Kläning; U. Karst; Wilhelm Pötter; Peter A. Czeschinski; Ute Witting (pp. 270-273).
Solid sorbents coated with the fluorescent reagent 5-dimethylaminonaphthalene-1-sulfohydrazide (dansylhydrazine, DNSH) have been used for derivatization and quantitative determination of airborne carbonyl compounds, for example in investigations on atmospheric pollution. The evaluation of this derivatization reaction presented here revealed that, for several reasons, it may not be recommended when sampling is performed with impingers containing liquid reagent solutions. Derivative yields came out to be strongly influenced by water and phosphoric acid which are essential for sufficient derivatization rates, but also responsible for the degradation of derivatives. Even at water and acid concentrations considered as an optimal compromise between accelerating and degrading effects, the analytical reliability of the method can only be guaranteed under controlled laboratory conditions. The reduced or lacking reactivity of DNSH towards aromatic aldehydes or aliphatic and aromatic ketones is an additional finding discarding the DNSH method for routine air monitoring at least when impingers are used for sampling.
Development of a solid-phase extraction and derivatization method for polar carboxylic acids from aqueous extracts of inorganic multi-component incineration residues by H. Hirschlag; R. Köster (pp. 274-280).
A rapid and reliable GC/MS (EI and CI) method was developed for the identification of short-chain mono- and dicarboxylic acids in complex and strongly alkaline residues of municipal waste incineration. Such residues contain organic carboxylic acids in the mg/kg to μg/kg range, which may contribute to the mobilization of heavy metals. However, the alkalinity and the high salt loads of the matrix were found to be a serious problem in the analysis of short chain acids. Extraction with water, solid phase extraction, and derivatization were studied under these conditions. Solid-phase extraction with polymeric sorbents and derivatization with diazomethane can be combined in a reproducible manner to yield a robust and simple method which can be applied for screening unknown solids due to its wide applicability and the well identifiable methyl esters. Absolute recovery rates varied between 20 and 85% depending on the individual acids.
The capability of ultrafiltration and ETV-ICP-MS for size fractionation studies of arsenic and selenium species in ground water samples with high concentrations of iron, manganese and sulfur by M. Rässler; B. Michalke; P. Schramel; S. Schulte-Hostede; A. Kettrup (pp. 281-284).
A simple, but highly sensitive procedure for the determination of particular and colloidally bound arsenic and selenium species in ground water samples with high concentrations of iron, manganese and sulfur is presented. Samples were first filtered through a 0.45 μm filter to separate the particulate matter from the dissolved. Aliquots of the filtered sample were submitted to ultrafiltration through membrane filters with pore diameters of 30 nm and 1 nm, respectively. Filtrates were analyzed by ETV-ICP-MS for their arsenic and selenium concentration.
Determination of Cd, Cu, Pb and Sb in environmental samples by ICP-AES using polyaniline for separation by A. C. Sahayam (pp. 285-288).
The anion exchange properties of polyaniline for Cd, Cu, Pb and Sb in potassium iodide were studied. The analytes converted into anionic complexes by KI (0.03–0.96 mol/L) in HCl were adsorbed on polyaniline and eluted with HNO3. The optimum conditions for adsorption and elution were determined. Quantitative recoveries were obtained for Cd, Cu and Pb, whereas, the recoveries for Sb were about 75%. This separation procedure was used with subsequent ICP-AES determination for Cd, Cu, and Pb in NIST-coal fly ash (1633b) and a sea plant with an R.S.D of 5% (n = 5).
Sensitive determination of airborne diisocyanates by HPLC: 4,4′-Diphenylmethane-diisocyanate (MDI) by M. Schulz; T. Salthammer (pp. 289-293).
An HPLC/fluorescence method is described, which enables the sensitive determination of airborne monomeric 4,4′-diphenyl-methane-diisocyanate (MDI). A glass fiber filter coated with 1 mg 1-(2-pyridyl)-piperazine (2PP) is used for sampling. The urea derivative MDI-2PP, which shows a high molecular absorption coefficient and exhibits a sufficient fluorescence response, is extracted from the filter by use of a 90:10 acetonitrile/DMSO mixture. Linear calibration curves were obtained for the indoor range (7.8 ng/mL to 74.7 ng/mL) and the workplace range (27.7 ng/mL to 676.0 ng/mL). A detection limit of 9.0 ng/m3 can be achieved on a total sampling volume of 1000 L. The method is easy to handle and therefore highly suitable for a routine determination of MDI in the atmosphere of workplace areas and living environments.
Performance of total reflection and grazing emission X-ray fluorescence spectrometry for the determination of trace metals in drinking water in relation to other analytical techniques by B. Hołyńska; Mariusz Olko; Beata Ostachowicz; Jerzy Ostachowicz; Dariusz Węgrzynek; Martine Claes; Rene Van Grieken; Pieter de Bokx; Peter Kump; Marijan Necemer (pp. 294-298).
An intercomparison survey has been carried out in order to evaluate the performance of two related X-ray fluorescence techniques as compared to the achievements of several other analytical techniques applied for trace elements determination in drinking water. A relatively new technique, total reflection X-ray fluorescence (TXRF) and a novel related technique, grazing emission X-ray fluorescence (GEXRF) have been used for the analysis of a mineral water sample. The concentrations of the following elements have been determined: Na, Mg, K, Ca, Ni, Cu, Zn and Sr. The mineral water sample has also been analyzed by a number of other analytical techniques, routinely utilized in drinking water quality control. The analyses were performed in eleven laboratories which reported 286 individual determinations producing 75 laboratory means. From the obtained results, it can be concluded that the TXRF technique is suitable for a direct determination of heavy elements in drinking water (above potassium, Z = 19). This technique can compete with other analytical techniques routinely used in water quality monitoring. First results obtained with GEXRF spectrometry show that this technique can be successfully applied for the determination of low-Z elements in drinking water. However, results for sodium and magnesium were systematically too low, indicating that modifications of the quantification procedure may be required to improve the accuracy of determination for these light elements.
Comparison between CP/MAS 13C-NMR and pyrolysis-GC/MS in the structural characterization of humins and humic acids of soil and sediments by D. Fabbri; M. Mongardi; L. Montanari; G. C. Galletti; G. Chiavari; R. Scotti (pp. 299-306).
The chemical structure of humins (HUs) and humic acids (HAs) of terrestrial and marine environments was investigated by cross-polarization magic angle spinning 13C-nuclear magnetic resonance spectroscopy (CP/ MAS 13C-NMR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Samples of HUs and HAs were obtained from sediments of the Adriatic Sea, the Lagoon of Ravenna (Adriatic Sea) and the Bubano Lake as well as from an agricultural soil. HUs displayed pyrograms and NMR spectra different from those of related HAs. According to NMR spectra HUs were more aliphatic and contained fewer carboxyl groups than HAs, while pyrolysates of HUs were characterized by higher levels of products arising from carbohydrates and lower levels of lignin methoxyphenols with respect to HAs. The relative content of paraffinic carbons determined by NMR was in good agreement with the relative abundance of unbranched aliphatic hydrocarbons released by pyrolysis. Both techniques evidenced the importance of polymethylene structures in HUs.
Determination of carbaryl in foods by solid-phase room-temperature phosphorimetry by L. F. Capitán-Vallvey; Mahmoud K. A. Deheidel; R. Avidad (pp. 307-312).
A phosphorimetric solid phase assay is proposed for the determination of the pesticide carbaryl (CBL) at room temperature. CBL was spotted on filter paper together with Tl(I) as heavy metal, and dried for 3 min, after which the diffuse transmitted phosphorescence was measured using two quartz plates to avoid the quenching effect produced by atmospheric oxygen. The linear dynamic range was 0.5–4.0 μg/mL and the detection and quantification limits were 0.09 and 0.31 μg/mL, respectively. The precision of the method, expressed as relative standard deviation, was 2.3% for a sample containing 2.0 μg/mL of CBL. The method was applied to the determination of CBL residues in cereals, potatoes and waters, obtaining recoveries ranging between 92 and 105%.
A new method for the analysis of arsenic species in urine by using HPLC-ICP-MS by J. Lintschinger; P. Schramel; A. Hatalak-Rauscher; I. Wendler; B. Michalke (pp. 313-318).
Urinary arsenic speciation is considered to be an effective procedure to differentiate between toxic inorganic and less toxic organic arsenic exposure. The aim of the present work was to develop a new method for the simultaneous determination of the main arsenic species so far detected in urine: arsenite (As(III)), arsenate (As(V)), methylarsonic acid (MA), dimethylarsinic acid (DMA), and arsenobetaine (AsB). The method is based on anion exchange HPLC coupled on-line to an inductively coupled plasma mass spectrometer (ICP-MS) for element specific detection. Experimental parameters, such as column type and composition of the mobile phases were optimized in order to get best separation, little matrix interferences, lowest detection limits, and short total times of analyses. Best chromatographic conditions were obtained by using a Dionex AS14 anion exchange column and a gradient elution with tetramethylammonium hydroxide and ammonium carbonate as eluting compounds. The detection limits (3 σ) were found to be in the sub μg L–1 range. The method was applied to analyze different urine samples from persons with and without consumption of seafood. To avoid significant matrix influences, samples (24 h urine) had to be diluted 1 : 5 with water and were filtered through a 0.45 μm filter prior to analyses. Special attention was focused on the validation of the method according to the regulations of the “Deutsche Forschungsgemeinschaft” (DFG) for the analyses of hazardous substances in biological materials.
Determination of total iron in ground waters and multivitamin tablets using a solid-phase reactor with tiron immobilised on amberlite ion-exchange resin in a flow injection system by J. F. van Staden; L. G. Kluever (pp. 319-323).
A method is described for the flow injection determination of total iron as Fe(III) using a solid-phase reactor containing disodium-1,2-dihydroxybenzene-3,5-disulphonate (tiron) as substrate. The iron(III) reacted with tiron to form a complex which absorbs strongly at 667 nm, where it was measured spectrophotometrically. The system has a linear range of 1 to 50 mg L–1 with a detection limit of 0.67 mg L–1. It is suitable for the determination of total iron in multivitamin tablets and iron-rich ground waters, with a relative standard deviation of better than 1.1%. The results obtained compared favourably with the certified values and a standard ICP-AES method.
Determination of the ethylene oxide adduct S-(2-hydroxyethyl)cysteine by a fluorometric HPLC method in albumin and globin from human blood by Dörte M. Vollmer; R. Thier; Hermann M. Bolt (pp. 324-328).
A new method has been developed for the quantification of 2-hydroxyethylated cysteine resulting as adduct in blood proteins after human exposure to ethylene oxide, by reversed-phase HPLC with fluorometric detection. The specific adduct is analysed in albumin and in globin. After isolation of albumin and globin from blood, acid hydrolysis of the protein and precolumn derivatisation of the digest with 9-fluorenylmethoxycarbonylchloride, the levels of derivatised S-hydroxyethylcysteine are analysed by RP-HPLC and fluorescence detection, with a detection limit of 8 nmol/g protein. Background levels of S-hydroxyethylcysteine were quantified in both albumin and globin, under special consideration of the glutathione transferase GSTT1 and GSTM1 polymorphisms. GSTT1 polymorphism had a marked influence on the physiological background alkylation of cysteine. While S-hydroxyethylcysteine levels in “non-conjugators” were between 15 and 50 nmol/g albumin, “low conjugators” displayed levels between 8 and 21 nmol/g albumin, and “high conjugators” did not show levels above the detection limit. The human GSTM1 polymorphism had no apparent effect on background levels of blood protein 2-hydroxyethylation.
Methods for the determination of neutral drugs as well as betablockers and β2-sympathomimetics in aqueous matrices using GC/MS and LC/MS/MS by T. A. Ternes; Roman Hirsch; Jutta Mueller; Klaus Haberer (pp. 329-340).
An analytical method has been developed which allows the determination of 22 different neutral and weakly basic drugs belonging to several different medicinal classes like antiphlogistics, betablockers, β2-sympathomimetics, lipid regulators, antiepileptic agents, psychiatric drugs and vasodilators in waste water as well as in river and drinking water. A method including solid phase extraction, derivatization by silylation and detection by GC/MS permits detection down to 5 ng/L. The recovery rates mostly exceeded 70%. However, the determination of phenazone, carbamazepine, cyclophosphamide, ifosfamide and pentoxiphylline is frequently disturbed by organic co-extractants in real samples of rivers and waste waters. Therefore, a time saving alternative method has been developed, combining solid phase extraction (as an enrichment step) together with detection by LC-electrospray/MS/MS allowing the measurement of 5 neutral drugs. Detection limits down to 10 ng/L have been achieved even for organically highly contaminated waters like sewage treatment plant effluents.
Constant-wavelength synchronous spectrofluorimetry for determination of riboflavin in anchovies by T. J. López y López-Leytón; M. A. Lage Yusty; M. E. Alvarez Piñeiro (pp. 341-343).
Constant-wavelength synchronous spectrofluorimetry was used for the analysis of riboflavin in anchovies. Synchronous fluorescence spectra were recorded between 300 and 600 nm at a scan rate of 240 nm min–1 and with excitation and emission slit-widths both set to 5 nm. The excitation-emission wavelength difference was 65 nm. The fluorescence was measured by peak-area base between 430–509 nm. Recovery was higher than 90.8%.
Determination of the pesticide Chlorpyrifos by cathodic adsorptive stripping voltammetry by M. S. El-Shahawi; M. M. Kamal (pp. 344-347).
The adsorption behavior and differential pulse cathodic adsorptive stripping voltammetry of the pesticide Chlorpyrifos (CP) were investigated at the hanging mercury drop electrode (HMDE). The pesticide was accumulated at the HMDE and a well-defined stripping peak was obtained at –1.2 V vs Ag/AgCl electrode at pH 7.50. A voltammetric procedure was developed for the trace determination of Chlorpyrifos using differential pulse cathodic adsorptive stripping voltammetry (DP-CASV). The optimum working conditions for the determination of the compound were established. The peak current was linear over the concentration range 9.90 × 10–8– 5.96 × 10–7 mol/L of Chlorpyrifos. The influence of diverse ions and some other pesticides was investigated. The analysis of Chlorpyrifos in commercial formulations and treated waste water was carried out satisfactorily