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Analytical and Bioanalytical Chemistry (v.356, #6)
Empirical procedure for the reduction of mixed-matrix effects in inductively coupled plasma atomic emission spectrometry using an internal standard and proportional correction by Jan L. M. de Boer; Maurice Velterop (pp. 362-370).
The matrix effects for single-matrix component (Na or Ca) and mixed-matrix component (Na plus Ca) systems were investigated for an inductively coupled plasma with radial viewing and employing ultrasonic nebulization. Correction for matrix effects was carried out using the internal standard ratio method and a method named ‘proportional correction’, both with scandium and yttrium as internal standard elements. The best correction was observed using proportional correction both for the single-matrix component systems and for the mixed-matrix component system.
Spectrophotometric determination of thallium in zinc and zinc-base alloys with iodoacetic acid and hexamethylenetetramine by Dragan Mihajlović; Trajče Stafilov (pp. 371-374).
Thallium(III) forms a ternary complex of yellow colour with iodoacetic acid and organic bases, especially hexamethylenetetramine. The complex is soluble in water and various organic solvents. Zinc, copper, cadmium and iron do not form complexes with these reagents, so that a spectrophotometric determination of thallium in zinc and its alloys is possible. The limit of detection is 15 μgg−1, the molar absorption coefficient about 2000 mol−1l−1 cm−1.
Separation of Cr(III) and Cr(VI) using melamine-formaldehyde resin and determination of both species in water by FAAS by B. Demirata; I. Tor; H. Filik; H. Afşar (pp. 375-377).
A method is described for the determination of Cr(VI) and total chromium by FAAS. Cr(VI) is separated from Cr(III) by adsorption on melamine-formaldehyde resin. After elution of Cr(VI) with 0.1 mol/l NaAc solution, it is analysed by FAAS. Total chromium is determined by FAAS after conversion of Cr(III) to Cr(VI) by oxidation with hydrogen peroxide, total Cr(VI) is concentrated as above. If the total concentration of chromium is sufficient, the determination can be directly made by FAAS. Cr(III) can then be calculated by subtracting Cr(VI) from the total Cr. This method was successfully applied to the determination of chromium in lake water.
Analytical characterization of the persistent residues after microbial degradation of mineral oils by Volker Riis; Dietmar Miethe; Monika Möder (pp. 378-384).
The residual fractions remaining after microbial degradation of diesel fuel, different deparaffinized raffinates and extracts from long-term contaminated soils were analyzed by liquid chromatography, gas chromatography, infrared spectrometry and mass spectrometry. The quantity of saturated hydrocarbons decreased after the microbial treatment, whereas the portion of polar compounds increased. The total content of aromatics changed only insignificantly. n-Paraffins < C26 were found to be no longer present in mineral oils degraded to exhaustion. Infrared spectrometry revealed oxygen compounds in the residues, mainly ketones, fatty acids and esters. Elementary analysis confirms the presence of nitrogen, oxygen and sulphur compounds in the degraded products. The gas chromatograms of high boiling oils, as well as of residues and extracts, consist mainly of a large base “envelope” (about 95% of the total area); thus gc/ms coupling reaches the limits of its applicability. However, mass spectrometry with direct inlet gives valuable information regarding hydrocarbon type analysis. The results revealed the preferable degradation of alkanes, 1-ring aliphatics and benzenes and an enrichment of condensed cycloaliphatics and aromatics. The latter compounds are known to be resistant to microbial attack.
Determination of carbonyl compounds in exhaust gas by using a modified DNPH-method by Jörg Lange; Stephan Eckhoff (pp. 385-389).
The determination of carbonyl compounds in gaseous samples is usually accomplished by enrichment methods, in which 2,4-dinitrophenyl-hydrazine (DNPH) as a derivatization reagent has become established to a large extent. However, the conventional methods of DNPH-impingers and of DNPH-cartridges are applicable to emission measurements in a limited way only, depending on the NO2-concentration in the exhaust gas. It could be proved that DNPH-derivatives, as well as DNPH, are also decomposed by NO2 at a different speed, in which the hydrazones of unsaturated carbonyl compounds are probably more sensitive than those of the saturated carbonyl compounds. In view of this fact, the collecting methods had to be modified to avoid losses with the enrichment. The analysis of the compounds is carried out by HPLC with an effective gradient-system which is able to separate and detect the carbonyl compounds in exhaust gas within 16 min. Furthermore, a simple working-up procedure is presented which facilitates a parallel analysis by GC.
Determination of aromatic hydrocarbons in air using diffusion denuders by Uwe Risse; Elke Flammenkamp; Antonius Kettrup (pp. 390-395).
The results of a study to evaluate a recently developed denuder sampling system for the determination of aromatic hydrocarbons in air are presented. Denuders of different lengths were tested in laboratory experiments by means of dynamically generated test gases at conditions similar to those at workplaces. Uptake rates, adsorption capacities as well as desorption efficiencies were measured at different sampling parameters. The influence of air humidity on the adsorption behaviour was determined. Finally, the suitability of the system for outdoor air investigations was checked. The denuders were very suitable for the determination of aromatic hydrocarbons in workplace air; the general feasibility to investigate outdoor air samples was demonstrated.
Modified sampling and analysis method for large volatility range airborne polycyclic aromatic hydrocarbons (PAH) using gas chromatography-mass spectrometry by S. Wybraniec; A. P. de Jong (pp. 396-402).
A sampling method has been developed for the measurement for polycyclic aromatic hydrocarbons in ambient air by gas chromatography isotope dilution mass spectrometry. The method has been designed to measure the largest possible volatility range of PAHs including the abundant naphthalenes. Sample volumes were approx. 500m3 in size at a sampling rate of approx. 18m3/h. The sampler contained three sorption stages for the simultaneous capturing of particle bound and low and high volatile gaseous PAH, respectivley. Recoveries of sampling spikes were on average 90%. The detection limit was approx. 5 pg/m3 for the high boiling range PAH. Results obtained showed a quite steady profile for most PAH in background air in The Netherlands. Comparison of abundance ratios with literature data indicate that traffic exhausts are the major source for the PAH in the area.
Determination of resin acids in pulp mill EOP bleaching process effluent by Friederike Dethlefs; Hans-Jürgen Stan (pp. 403-410).
Resin acids are tricyclic diterpenoids which are natural constituents of the wood from conifers. They are released from the wood during the manufacture of pulp and paper. These acids are very resistant to chemical degradation and survive the pulping and also the EOP bleaching process (EOP = alkaline extraction, oxygen and peroxide, the chemicals used in the bleaching process). Resin acids were extracted from alkaline medium using liquid-liquid extraction with t-butyl methyl ether and solid phase extraction with RP C18 adsorbent and a highly porous polystyrene-divinylbenzene polymer. After conversion of the acids to their pentafluorobenzyl esters, the extracts were analysed by GC/MS using a 25 m OV17 capillary column. Recovery values for single resin acids were determined by all three extraction methods. The solid phase extraction methods were applied to the analysis of the EOP effluent from a pulp mill bleaching process. 14 different resin acids and one resin acid methyl ester have been identified in the effluent. One of these was an oxo resin acid which might well be a product of the bleaching process.