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Analytical and Bioanalytical Chemistry (v.362, #6)
Comparability and traceability of coal ash analyses in an interlaboratory study program by A. M. H. van der Veen; A. J. M. Broos (pp. 503-507).
From results obtained in an interlaboratory study program, performance characteristics for the determination of major and minor elements in coal ash have been established. For several parameters, a functional relationship between the content (grand mean) and the reproducibility and reproducibility standard deviations could be established: Fe2O3, MnO2, Na2O, K2O, MgO, CaO, and SO3 content in ash. In the interlaboratory study program, it was verified that the data between rounds were comparable. This verification was carried out using blind samples.
Iodine determination in biological materials Options for sample preparation and final determination by G. Knapp; B. Maichin; P. Fecher; S. Hasse; P. Schramel (pp. 508-513).
This paper describes the development of various new acid sample decomposition methods, as well as an extraction (leaching) method and compares them with the “Schöniger Combustion” technique. The methods have been developed as sample preparation techniques for iodine determination in biological materials, especially in solid samples. ICP-MS (inductively coupled plasma mass spectrometry) and a catalytic technique are employed and discussed for the final determination of iodine concentrations. Accuracy and reliability of the different analytical methods are shown in the examples of different CRMs (certified reference materials) available for iodine. The results of an interlaboratory comparison are specifically presented for the extraction (leaching) method.
Preparation and evaluation of a functionalized polymer-coated silica based sorbent for metal ion separation by Jaw-Cherng Hsu; Chin-Hung Chang; C.-Y. Liu (pp. 514-521).
A silica based sorbent with an anion complexone polymer coating, [24]ane-N6 macrocycle, was prepared. The chelation properties of this material were investigated by elemental analysis, infrared spectra and Voige’s method. The polymer-coated silica column (25– 40 μm, 100 × 4.6 mm i.d.) was employed for trace metal analyses. Oxalic acid, malonic acid, succinic acid, citric acid, phthalic acid and acetic acid were used as mobile phases. Their retention characteristics were elucidated. Oxalic acid was found to be the most effective eluent. With a mobile phase consisting of oxalic acid (25 mM) and sodium nitrate (25 mM) at pH 4.2, the separation of copper(II), cadmium(II), cobalt(II) and zinc(II) in sea water could be achieved. The identification of metal ions was performed at 510 nm using 4(2-pyridylazo)resorcinol (1 × 10–4 M) as post column reagent. The limits of detection were 5 × 10–7 M, 1 × 10–5 M, 3 × 10–5 M and 2 × 10–6 M for copper(II), cadmium(II), cobalt(II) and zinc(II) based on three times the standard deviation of the response for the lowest concentration (n = 5) in the chromatogram with a sample volume of 50 μL. For evaluation of data reliability, oyster tissue (NIST SRM 1566 a) was studied with the proposed system.
Platinum and rhodium in a polluted environment: studying the emissions of automobile catalysts with emphasis on the application of CSV rhodium analysis by E. Helmers; Norbert Mergel (pp. 522-528).
An analytical approach is presented that utilizes CSV (cathodic stripping voltammetry) determination of Pt and Rh in polluted common grass, successfully discriminating trends in the imission situation. A sampling strategy was developed leading to clear spatial trends. It is shown that additional detection of Rh helps to confirm accuracy even of peak Pt concentrations. Applicability and reliability of CSV Rh (and Pt) detection is proven during comparative measurements in other laboratories. Independent instrumental methods (ICP-MS, docimasy) confirmed CSV results, particularly in the case of Rh. In 1997, concentrations of Pt and Rh in grass samples were found to be 2.7 times higher than in 1994, and in dust samples 3.9 times higher than in 1994, respectively. Percentage of cars equipped with catalytic converters, on the other hand, was 2.4 times higher in 1997 compared with 1994. Some of the first rhodium concentrations in environmental samples are reported.
Determination of the plasticizer N-butylbenzenesulfonamide and the pharmaceutical Ibuprofen in wastewater using solid phase microextraction (SPME) by N. Huppert; Marion Würtele; Hermann H. Hahn (pp. 529-536).
A rapid, inexpensive and solvent-free method for the simultaneous determination of the polyamide plasticizer N-butylbenzenesulfonamide (NBBS) and the widely used pharmaceutical Ibuprofen by solid phase microextraction (SPME) combined with gas chromatography/mass spectrometry (GC/MSD) in wastewater samples was developed. Besides the optimized analytical conditions, results of investigations with varying analytical parameters are reported. Problems, which may occur during the analytical procedure (e.g. salt deposits, adsorption phenomena, carry-over), are discussed. For the determination of Ibuprofen, it is important to carry out the extraction under acidic conditions with sufficiently buffered samples; the GC/MSD system must be very clean and well maintained. SPME allows an extraction of Ibuprofen without derivatization of its carboxylic group. For quantification in complex matrices, the standard addition technique is necessary. Limit of detection and limit of determination are 0.1 μg/L for both analytes. NBBS and Ibuprofen were detected in several raw and treated wastewater samples from municipal wastewater treatment plants in the range from < 0.1 to 3.5 μg/L.
Fluorescence immunoassay of α-1-fetoprotein with hemin as a mimetic enzyme labelling reagent by Qing-Zhi Zhu; Feng-Hua Liu; J.-G. Xu; Wen-Jin Su; Jian-Wei Huang (pp. 537-540).
A novel mimetic enzyme immunoassay to determine α-1-fetoprotein (AFP) in solution was developed. Hemin, a horseradish peroxidase substitute, was used as a labelling reagent to catalyze the reaction of p-hydroxyphenylacetic (HPA) and hydrogen peroxide in alkaline media. In the competitive immunoassay, monoclonal anti-AFP antibody was coated on a 96-well plate (polystyrene) and a constant amount of hemin-labelled AFP and a known volume of test solution were added. Non-labelled and hemin-labelled AFP compete for binding to the plate-bound antibody. After the immunoreaction, the immunochemically adsorbed hemin-AFP conjugate moiety was determined by measuring the fluorescence produced in a solution containing HPA and hydrogen peroxide. The calibration graph for AFP was linear over the range 0 ∼ 380 ng/ well with a detection limit of 1.0 ng/well. The method has been applied to determine the AFP in human blood serum with satisfactory results.
Capabilities of high resolution inductively coupled plasma mass spectrometry for trace element determination in plant sample digests by Ilia Rodushkin (pp. 541-546).
The analytical performance of inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of plant sample digests was evaluated using double focusing sector field ICP-MS (ICP-SMS). Instrumental detection limits of ICP-SMS are superior to those obtained by quadrupole systems (ICP-QMS) and reach the fg mL–1 range for elements with high m/z ratios. Matrix effects caused by a plant digest after sample preparation resulting in 200-fold dilution were found to be negligible. The usefulness of high mass resolution for overcoming some spectral interferences is demonstrated. Mathematical correction possibilities could be necessary to improve accuracy. The concentrations of more than 20 elements can be determined in 5 min and only one internal standard is necessary to correct for instrumental drift.
Evaluation of a mixed immunosorbent for selective trace enrichment of phenylurea herbicides from plant material by S. Herrera; A. Martín-Esteban; P. Fernández; D. Stevenson; C. Cámara (pp. 547-551).
A mixed immunosorbent, composed of anti-isoproturon and anti-chlortoluron antibodies immobilized on aldehyde-activated silica was evaluated for the trace enrichment and clean-up of several phenylurea herbicides from potatoes, carrots and peas. As the immunosorbent exhibited non-specific interactions with the matrix components, a previous clean-up step based on gel filtration (Sephadex G-25 PD-10 column) or anion-exchange (Power 1 × 8 Dionex column) was necessary. The coupling of gel filtration and immunosorbent with subsequent HPLC/UV determination allowed the determination of selected herbicides in potatoes in the 30 ng/g range with high precision, but for more complex samples (carrots and peas) the combination of anion-exchange resin and immunosorbent was required. With 30 ng/g spiked samples recovery rates for isoproturon, chlortoluron, metobromuron, linuron and chlorbromuron averaged 80 ± 20% (n = 5 in two consecutive days) for the whole procedure and the estimated detection limits ranged from 5 to 20 ng/g.