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Analytical and Bioanalytical Chemistry (v.364, #8)
Inverse-variance weighted regression with uncertainty in both variables for the quantitative description of traffic-emitted lead transfer into plants by J. W. Einax; W. Bremser; B. Machelett (pp. 673-677).
A comprehensive screening study of traffic-emitted lead pollution of soil and plants was carried out. In a first step of data evaluation the influence of the factors traffic density and distance from the road was excluded to describe the bivariate relationship between plant lead and soil lead contents. Then the application of inverse-variance weighted regression which takes into account the considerable uncertainty of the data obtained enabled the quantitative determination of the soil-plant lead transfer.
Study of interference in the flame atomic absorption spectrometric determination of lithium by using factorial design by B. Baraj; Luis F. H. Niencheski; Ronaldo D. Trapaga; Rosiléa G. França; Valbona Cocoli; Daniel Robinson (pp. 678-681).
The severe interference of a number of metallic ions found in brines, marine sediments and sea water in the determination of lithium is demonstrated. Calcium, iron and sodium significantly depressed the absorption signal on lithium in an air/acetylene flame. Aluminium, magnesium and strontium up to 1500, 1000 and 200 μg/mL, respectively, showed no interference in the determination of lithium under the same conditions. Potassium produced some suppression of the lithium signal at levels in excess of 1500 μg/mL. Experimental data were examined using the factorial design method. Interference was demonstrated in two synthetic samples (models of “brine” and “marine sediments” ) and natural marine sediment. It was possible to eliminate all interferences using a higher temperature (nitrous oxide/acetylene flame). In addition, by using the standard addition method the interference disappeared, which confirmed the interference as a proportional systematic error.
Arylboronic compounds – novel carriers for catecholamine selective membrane electrodes by I. V. Pletnev; Nataliya V. Shvedene; Irina V. Lyutikova; Inna A. Nazarova; Ilya M. Litvak; Irina V. Mikhura; Yury A. Zolotov (pp. 682-685).
Arylboronic acids are used as novel carriers for membrane electrodes suitable for direct potentiometric determination of the catecholamine drug dobutamine. The carriers are capable of binding diol groups of catecholamines; solvent extraction data confirm the formation of an 1 : 1 complex. For the electrode based on octyloxyphenylboronic acid, the slope of electrode function is S = 58 mV decade–1; the detection limit is 1.7 · 10–5 mol/L, the linear range 5 · 10–4– 1 · 10–2 mol/L, the response time 10–20 s. The results suggest the potential use of boronic carriers for the detection of biogenic catecholamines.
Characterization and application of an electrode modified by mechanically immobilized copper hexacyanoferrate by D. Ravi Shankaran; S. S. Narayanan (pp. 686-689).
A newly modified electrode was prepared by mechanical immobilization of copper hexacyanoferrate (CuHCF) on a graphite electrode. The modified electrode was characterized by cyclic voltammetric experiments. The effect of different background electrolytes, pHs and scan rates on the electrochemical behaviour of the electrode has been evaluated. In NH4Cl two reversible redox peaks were observed. The first redox peak corresponding to Cu+/Cu2+ is observed only in this medium. The second redox peak corresponds to the Fe(CN)6 4–/Fe(CN)6 3– couple. Both anodic peaks were used for catalytic oxidation of ascorbic acid. As the anodic current for catalytic oxidation was proportional to the amount of ascorbic acid, an analytical method was developed for the determination of ascorbic acid in commercial samples.
Lead selective membrane electrode using cryptand(222) neutral carrier by M. K. Amini; M. Mazloum; A. A. Ensafi (pp. 690-693).
The construction, performance characteristics and applications of a polymeric membrance electrode for lead(II) ion are reported. The electrode was prepared by incorporating cryptand(222) as the neutral carrier into a plasticized poly(vinyl chloride) membrane. The influence of membrane composition, pH and concentration of internal reference solution were investigated. The electrode exhibits a potentiometric response for Pb2+ ion over the concentration range 10–1–10–5 M with a detection limit of 5 × 10–6 M Pb2+. It shows a relatively fast response time of about 30 s and can be used for about two months without any considerable divergence in potential. The proposed sensor revealed good selectivities for Pb2+ in the presence of several metal ions and could be used in the pH range of 2.5 to 7.5. It was used as an indicator electrode in the potentiometric titration of Pb2+ with EDTA.
Automated matrix separation and preconcentration for the trace level determination of metal impurities in ultrapure inorganic salts by high-resolution ICP-MS by Oliver Keil; Joachim Dahmen; Dietrich A. Volmer (pp. 694-699).
A rapid and simple analytical method for the determination of transition metals and rare earth elements at sub-ng/g levels in alkaline and earth alkaline salt matrices was developed. Automated solid-phase extraction was utilized for matrix separation and analyte preconcentration from highly concentrated brine solutions. The HPLC system used was equipped with a chelation column packed with an iminodiacetate-based resin. Detection was accomplished by means of high-resolution inductively-coupled plasma mass spectrometry (ICP-MS), which allowed quasi-simultaneous multi-element determinations. A microconcentric nebulizer was employed for HR-ICP-MS to determine the elements of interest in small volumes of sample extracts. The method was shown to be very sensitive with limits of quantification in the range of 1–40 ng/g for all investigated elements. The method exhibited excellent precisions, high analyte recoveries, linear responses of least three orders of magnitude, high accuracy and low contamination susceptibility. A comparison of automated solid-phase extraction with methodologies utilizing traditional liquid-liquid extraction showed that the former offered similar analytical performance but was clearly easier to use and faster to perform, resulting in substantial time, labor and cost savings.
Determination of SiO2 in lime mud by gravimetry by R. Matilainen; J. Tummavuori (pp. 700-704).
A simple and rapid method for the determination of SiO2 in lime mud used in current sulfate pulping practice is reported. The lime mud samples are treated three times with 2.5 mL of 6 mol/L hydrochloric acid. The samples are nearly evaporated to dryness two times and the third time to complete dryness. To determine the exact SiO2 content of the residue, it is treated with an excess of concentrated hydrofluoric acid and a little hydrochloric acid, and the silica is expelled as volatile silicon tetrafluoride. The sample treatments take about 1.5 h and the heating periods take a total of about 3.5 h. The SiO2 results were evaluated by analyzing National Institute of Standards and Technology Standard Reference Materials, SRM, (1c, 694 and 88b). The method was found to be accurate and precise in a 95% confidence interval, rapid, and highly repeatable. The repeatability standard deviation for SRMs was calculated to be 0.49%.
X-ray fluorescence determination of total sulfur in fly ash by Vít Šprta; Bohumil Knob; P. Janoš (pp. 705-708).
Standard addition, double dilution and standard calibration were used for x-ray fluorescence (XRF) determinations of sulfur in fly ashes. Samples were analysed as pellets prepared by mixing with acrylate copolymer or with microcrystalline cellulose (in the case of the double dilution method). Lithium sulfate was used for the standard addition method and also as standard with known sulfur content for the double dilution method. Fly ashes analysed by optical emission spectrometry with an inductively coupled plasma (ICP-OES) were used as standards for the standard calibration XRF method. Sulfur was determined in the range of ca. 10–1–100 % S. For the fly ashes from the North-Bohemian brown coals, the differences between the XRF determinations and the ICP-OES determinations ranged from ca. 1.4 to 10% rel. and precision (repeatability) was better than 10% (RSD). The standard calibration method is suitable for routine analyses of real samples of similar nature. The methods of standard addition and double dilution are rather laborious in sample preparation compared with the standard calibration.
Generation of test gases from volatile and semivolatile organic compounds (VOC/SVOC) by B. Schick; U. Risse; A. Kettrup (pp. 709-713).
An apparatus for the continuous generation of test gases from organic compounds of the VOC (Volatile Organic Compounds) and SVOC (Semivolatile Organic Compounds) categories has been developed. The use of a new test gas generator together with a system of heated transfer lines enabled the dynamic generation of test gases also of components with relatively low vapour pressures. With the help of an on-line coupled gas chromatograph the actual test gas concentrations were monitored. The apparatus has been evaluated for the compounds n-decane and pyrene.
HPLC analysis of polycarboxylic acids used as durable press finishing agents/ organic catalysts for cellulosic material by Ch. Schramm; Beate Rinderer (pp. 714-719).
Cotton fabric is modified by means of polycarboxylic acids in combination with an inorganic or an organic catalyst in order to impart durable press properties. After the curing process the cellulosic specimen is washed off to remove both the portion of the polycarboxylic acid that has not reacted and the catalyst applied. The treated cellulosic fabric is saponified with a sodium hydroxide solution to extract the PCA that has reacted with the cellulosic material. Both the wash liquor and the saponification liquor are investigated by means of isocratic HPLC using Aminex HPX-87-H as stationary phase. Excellent separation of the various polycarboxylic acids that are applied as crosslinking agents or as organic catalysts is achieved. The HPLC method presented enables the identification and quantification of the polycarboxylic acids.
On-line monitoring of chromium aerosols in industrial exhaust streams by laser-induced plasma spectroscopy (LIPS) by R. E. Neuhauser; U. Panne; R. Niessner; P. Wilbring (pp. 720-726).
Ultrafine heavy metal aerosols can have severe toxic and carcinogenic effects when inhaled in higher concentrations. The objective of this work was to develop a mobile continuous emission monitor (CEM) based on laser-induced plasma spectroscopy (LIPS) for an on-line analysis of chromium aerosols. The LIPS emission sensor was installed in an electroplating facility for a fast monitoring of particulate emissions to provide instantaneous feedback for process control. The prototype was tested in cooperation with an independent laboratory, which determined the total chromium content and the Cr(VI)/Cr(III) ratio in the exhaust stream by conventional filter analysis. The system provided both the necessary time-resolution and detection limits (14 μg m–3) for emission monitoring below the legal threshold (1 mg m–3) values. A good correlation was found between the on-line LIPS measurement and the independent reference analysis.
Optimisation of the analytical detection of EDTA by HPLC in natural waters by Stéphanie Loyaux-Lawniczak; Jamaâ Douch; P. Behra (pp. 727-731).
Reversed-phase ion-pair liquid chromatography is often used to analyse traces of EDTA in natural water samples. Some perturbations due to the presence of major anions in samples, which can compete for ion pair formation with the Fe-EDTA complex used for the detection, have been observed but never estimated and quantified. A new operational method for determining EDTA in natural water samples is proposed by taking into account anion interactions. Qualitative and quantitative analyses of EDTA were performed with a synthetic water at various ionic strengths. From the effect of the ionic strength controlled by CaCl2, the concentration of the counter-ion tetrabutylammonium bromide (TBA+Br–) and the methanol of the mobile phase, optimal analytical conditions were proposed for a better determination of EDTA concentration. The limit of detection without preconcentration and the reproducibility defined as relative standard deviation were 5 μg/L and 3.6% (n = 12), respectively. This method was applied to natural samples.
Determination of lead in waters and sediments from the wetland Tablas de Daimiel National Park (Spain) by J. J. Berzas Nevado; L. F. García Bermejo; R. C. Rodríguez Martín-Doimeadios (pp. 732-736).
Electrothermal atomic absorption spectrometry (ETAAS) has been used for lead control in waters and sediments of the wetland Tablas de Daimiel National Park. The lead determination in the wetland water is hindered by an enhanced salt content, so matrix interference was evaluated. The use of stabilized temperature platform atomization technique, Zeeman background correction and palladium nitrate as matrix modifier were found advisable. For the sediments a closed-vessel microwave dissolution method has been proposed using a mixture of HCl-HNO3-HF and a heating time of 90 s. With subsequent ETAAS using platform atomization and Zeeman background correction, no chemical modification was necessary. Using these conditions, the interferences were completely removed for both waters and sediments and the calibration curve in ultrapure water (1% nitric acid) was linear up to 30 μg/L. The detection limits for waters and sediments were 0.95 μg/L and 0.78 μg/g, respectively. The accuracy of the proposed method for sediments was validated by analyzing certified reference materials (obtained values were within the certified ones) and spiked wetland sediments (mean recovery of 99.0%).
Characterization of groundwater humic and fulvic acids of different origin by GPC with UV/Vis and fluorescence detection by R. Artinger; G. Buckau; J. I. Kim; S. Geyer (pp. 737-745).
Gel permeation chromatography (GPC) was applied for recognizing the origin of groundwater humic and fulvic acids. GPC was performed with Fraktogel TSK HW-50 in 0.1 M NaCl, pH 8.5 (0.05 M phosphate buffer), 1 mM EDTA, with 10% by volume methanol added. Humic substances from groundwaters and sediments of four different aquifer systems in Germany were isolated, purified and characterized. Both UV/Vis and fluorescence detection were applied. UV/Vis detection was found to be more powerful in identifying differences between the various humic and fulvic acids. The four aquifer systems investigated (“Gorleben”, “Fuhrberg”, “Franconian Albvorland” and “Munich”) differed from one another with respect to hydrological and geochemical conditions. The results showed that the GPC-elution behavior reflects the geochemical environment and origin (source material and generation process) of aquatic humic and fulvic acids.
Functional group analysis of Suwannee River fulvic acid with reactive fluorescent probes by Leland M. Yates III; R. von Wandruszka (pp. 746-748).
The reactive functional group content of Suwannee River fulvic acid (SRFA) was determined by reaction with fluorescent probes. Reaction with a triflate (R-SO2CF3) provided the total reactive group content in SRFA, and pyrene butanoic acid was used to determine the hydroxyl and amino groups. After purification of the product, standard addition analysis was used for quantification. The total reactive site content of SRFA was found to be 13.9 mmol/g, of which 57% were carboxylic acids, and 43% hydroxyl and amino groups. These values compare well with those obtained by other methods.
Determination of the enantiomeric purity of amphetamine after derivatization with Sanger’s reagent (2,4-dinitrofluorobenzene [DNFB]) by simultaneous dual circular dichroism and ultraviolet spectroscopy by H. Hegedűs; A. Gergely; T. Veress; F. Zsila (pp. 749-752).
A new analytical procedure has been developed for the determination of the enantiomeric purity of amphetamine samples. It is based on the derivatization of amphetamine with 2,4-dinitrofluorobenzene and a subsequent measurement of the anisotropy factor by dual (CD/UV) spectroscopy. This factor depends on the enantiomeric composition and does not depend on the concentration, a feature that eliminates the systematic errors caused by the sample preparations such as dilution, weighing, etc. The main advantage of the approach is the fact that the new synthetized derivative can be measured in the visible wavelength region with significantly better sensitivity than the underivatized amphetamine. The applicability of the procedure is demonstrated by results obtained by analysis of model materials containing amphetamine enantiomers at different ratios.
Adsorptive stripping square-wave voltammetric behavior of insulin by J. J. Berzas Nevado; J. Rodriguez Flores; G. Castañeda Peñalvo (pp. 753-757).
The adsorptive stripping voltammetric behavior of bovine insulin has been studied by both differential pulse and square-wave techniques, leading to analytical methodologies for its determination in aqueous samples and pharmaceutical preparations. The application of a square-wave mode for the stripping of adsorbed bovine insulin has proved to be much more sensitive, yielding signals 20 times larger than those obtained by applying a differential pulse scan. The precision obtained for the voltammetric method, at a concentration level as low as 0.77 mg L–1 of the protein, was found to be 1.45% (RSD., n = 8) by SWS and 2.20% (RSD., n = 8) by DPS. The pharmaceutical product Actrapid containing biosynthetic human insulin was analyzed by both methods.
An improved ELISA for the determination of tobacco mosaic virus with linear sweep voltammetry detection based on a new system of PAP-H2O2-HRP by Shu-Sheng Zhang; K. Jiao; Hong-Yuan Chen; Cheng-Liang Zhang; Zuo-Fang Zhang (pp. 758-762).
An improved ELISA for the determination of tobacco mosaic virus (TMV) with linear sweep voltammetry based on a new system of p-aminophenol (PAP)- H2O2- horseradish peroxidase (HRP) has been developed. The enzymatic product 3-[(4-hydroxyphenyl)amino]-4-(2-amino-5-hydroxyphenyl)-6-[(4-hydroxyphenyl)imino]-2,4-cyclohexadiene-1-one, produced from HRP catalyzing the oxidation of PAP with H2O2, yields a sensitive linear sweep voltammetric response at a potential of –0.45 V (vs. SCE) in Britton-Robinson (BR) buffer solution. By using this voltammetric peak, HRP can be measured with a detection limit of 0.4 mU/L and a linear range of 1.0 ∼ 1.0 × 102 mU/ L. The detection limit for the clarified TMV is 4.0 ng/mL and the highest dilution ratio detected for the infected leaf sap is 1 : 3.9 × 106. The processes of the enzyme-catalyzed reaction and the electro-reduction of the product of the enzyme-catalyzed reaction have been investigated.
Investigation of the analytical performance of gliding spark source mass spectrometry (GSSMS) for the trace analysis of nonconducting materials by A. I. Saprykin; J. S. Becker; H.-J. Dietze (pp. 763-767).
A radiofrequency (rf) spark discharge in vacuum developing across the surface of dielectrics – a so-called gliding spark – has been applied to the direct mass spectrometric trace analysis of nonconducting materials. The special configuration of the electrodes strengthened the electric field over the surface of a nonconducting sample and created optimum conditions for the sputtering and ionization of the sample material. Mass spectrometric investigations of the charge composition of atomic ion and molecular ion formation in radiofrequency gliding spark plasma showed a significant difference to that of the original rf spark discharge between two conducting electrodes. The analytical figures of merit (reproducibility, relative sensitivity factors and detection limits of chemical elements) of gliding spark source mass spectrometry have been studied by using the glass standard reference materials NIST SRM 610 and 611 for the determination of trace elements in glass matrix.
Spark source mass spectrometric calibration of the local vibrational mode absorption of carbon in gallium arsenide on arsenic sublattice sites by B. Wiedemann; H. Ch. Alt; J. D. Meyer; R. W. Michelmann; K. Bethge (pp. 768-771).
An appropriate calibration of the local vibrational mode absorption of carbon in GaAs on arsenic sublattice sites, CAs, at wavenumber 582 cm–1 (77 K) is presented. Integrated absorptions Iα of CAs, the dominant acceptor in undoped monocrystalline GaAs, and calibrated carbon concentrations [C] were measured in single crystals using the methods FTIR and SSMS, respectively. A calibration factor fC = [C]/Iα of (7.1 ± 0.2) × 1015 cm–1 has been derived for 2.8 × 1014 cm–3≤ [C] ≤ 1.4 × 1016 cm–3 above a SSMS detection limit of [C]DL≅ 1.4 × 1013 cm–3. The carbon concentrations [C] = [C]SSMS/RSCC were calibrated with a relative sensitivity coefficient RSCC = [C]SSMS/ [C]TRUE of 3.1 ± 0.1. CPAA was used as a reference method for [C]CPAA≥ 4.4 × 1014 cm–3 in order to approximate [C]TRUE.
Spark source mass spectrometric assessment of boron and nitrogen concentrations in crystalline gallium arsenide by B. Wiedemann; G. Rädlinger; H. Ch. Alt; K. G. Heumann; K. Bethge (pp. 772-776).
The residual or doped element concentration [E] in GaAs measured by SSMS is only accurate with respect to the relative sensitivity coefficient RSCE. For a trace element concentration, the RSCE = [E]SSMS/[E]TRUE is set to unity, if no reference material or method is available to approximate the concentration to the true value. For boron a relative sensitivity coefficient of RSCB = 0.94 ± 0.08 was obtained using TI-IDMS as a reference method. RSCN = 1 is used for nitrogen determinations. A boron and nitrogen detection limit of 4.4 × 1013 cm–3 is achieved. SSMS was used as reference method to calibrate the FTIR factor fE = [E] / Iα due to the integrated local vibrational mode absorption Iα of atomic boron and nitrogen in GaAs. A factor of fB = (12.0 × 2.7) × 1016 cm–1 (517 cm–1) and fN = (7.4 ± 0.1) × 1015 cm–1 (472 cm–1) was obtained for a boron and nine nitrogen containing GaAs samples at 77 K and 10 K, respectively.
Investigation of the optimization of the recovery of mineral oil from water by U. Retter; M. Koch; I. Nehls (pp. 777-779).
A method has been derived to completely recover mineral oil dispersed in water. The method involves three steps: the emulsification of the mineral oil by adding amphiphiles, the breaking of the emulsion by adding salts and the extraction of the mineral oil by a non-polar aprotic solvent. Various amphiphiles and types and concentrations of salts were tested. By using amphiphiles with HLB numbers in the range 4.7 to 40 a complete recovery of the mineral oil could be obtained for a combination of salts Na2SO4 + NaH2PO4 with total ionic strength of 6 mol/L.
Analytical performance of high-voltage neon plasma in glow discharge optical emission spectrometry by K. Wagatsuma (pp. 780-782).
In a high-voltage Ne glow discharge plasma (Ne-GDP), calibration factors as well as the limit of determination were compared between atomic resonance lines and singly-ionized lines of copper and aluminium in optical emission spectrometry. These elements have intense ionic lines which are excited by resonance charge-transfer collisions of Ne ions. The ionic lines gave better detection sensitivity in the Ne-GDP, whereas the atomic resonance lines were commonly employed as analytical lines in the other plasma sources such as Ar-GDP and ICP. The limit of determination was 1.3 × 10–3 mass % for the Cu II 248.58 nm line and 1.0 × 10–3 mass % Al for the Al II 358.66 nm line at a discharge parameter of 1.60 kV/36 mA.
A direct chemiluminescence method for the determination of nucleic acids using Ru(phen)32+–Ce(IV) system by H.-Y. Han; Z.-K. He; Yun-E. Zeng (pp. 782-785).
A direct chemiluminescence method for the determination of nucleic acids has been developed based on the enhancement of nucleic acids on the chemiluminescence light emission of the reaction between Ru(phen)3 2+(phen = 1,10-phenanthroline) and Ce(IV). Under the optimum conditions, the calibration graphs are linear in the range of 5.0 × 10–8–5.0 × 10–5 g/mL for calf thymus DNA, 8.0 × 10–8–5.0 × 10–5 g/mL for fish sperm DNA and 1.0 × 10–7–3.0 × 10–5 g/mL for yeast RNA, respectively. The limits of detection are 1.0 × 10–8 g/mL for calf thymus DNA, 3.1 × 10–8 g/mL for fish sperm DNA and 5.2 × 10–8 g/mL for yeast RNA, respectively. The final procedure allows the successful determination of calf thymus DNA, fish sperm DNA and yeast RNA in six synthetic samples. This method is simple, rapid and specific.
Sampling and determination of hydrogen cyanide in cigarette smoke by Y. Jiang; N. Lu; Feng Yu; Qing Li; Hongding Xu (pp. 786-787).
A method for sampling and determination of hydrogen cyanide in cigarette smoke is described. Cigarette smoke is filtered through a glass fiber filter paper, and only gaseous compounds, such as hydrogen cyanide, are collected in a dilute sodium hydroxide solution. The cyanide is determined spectrophotometrically at 550 nm by the isonicotinic acid–pyrazolone method. Maximum absorbance is achieved within 10 min at room temperature, and remains constant for about 20 min. Beer’s law is obeyed in the range 0.04∼0.80 μg mL–1 cyanide, with a molar absorptivity of 3.48 × 104 L mol–1 cm–1.