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  • 1
    In: Analytical Chemistry, Nov 15, 1998, Vol.70(22), p.4827(9)
    Description: Accelerated solvent extraction (ASE) was used for the simultaneous extraction of semivolatile organic compounds (SOCs) including chlorobenzenes (1,2,3,4-tetra-, penta-, hexachlorobenzene), HCH isomers ([alpha]-,[Beta]-, [Gamma], [Delta]-, [Epsilon]-HCH), DDX (p,p[prime]-DDT, -DDE, -DDD), PCB congeners (28, 52, 101, 138, 153, 180), and PAHs (phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]pyrene) from mosses (Pleurozium sehreberi) growing in regional locations (central Germany) and pine needles (Pinus sylvestris L.) from southern Russia (near the Caspian Sea). The results were compared with those obtained by ultrasonic extraction (USE). Using mixed moss samples (thorough cleanup, only minor interference during GC/MSD analysis) from one location mainly served to optimize two parameters, extraction solvent and temperature. The most favorable extraction conditions proved to be n-hexane as the extraction solvent, two temperature stages of 40 and 120 [degrees] C, a pressure of 15 MPa, and three static cycles in each case. These conditions were then applied to the extraction of SOCs from the wax and the inner pine needle fraction, which beforehand had undergone extractive separation with dichloromethane. ASE was found to be especially advantageous in the case of higher multiple exposures to pollutants and the resultant complicated matrixes (oleiferous extracts, pollutant/matrix conjugates). Owing to the much better separation of analyte/matrix, in many cases increases of 1-2 orders of magnitude were obtained in the analytical values of the contaminated sample materials compared to those obtained with USE.
    Keywords: Biological Monitoring -- Methods ; Mosses -- Environmental Aspects ; Pines -- Environmental Aspects ; Volatile Organic Compounds -- Analysis
    ISSN: 0003-2700
    E-ISSN: 15206882
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  • 2
    In: Analytical Chemistry, March 15, 2000, Vol.72(6), p.1294(7)
    Description: Systematic investigations were performed to study the dependence of the extraction efficiency of persistent organic pollutants (POPs), including chlorobenzenes, HCH isomers, DDX, PCB congeners, and PAHs, on the accelerated solvent extraction (ASE) operating variables solvent and temperature. Mixed soil samples from two locations with considerable differences in soil properties and contamination in the Leipzig-Halle region (Germany) were used. The objective was to optimize ASE for the extraction of POPs from real soil samples and to improve on the results achieved with Soxhlet extraction (SOX). Solvents with differing polarities were tested. Quadruple and triple determinations were performed on the two soils, respectively, between 20 and 180 degrees C in 20 degrees C steps. All the results were compared with those obtained by SOX, as well as, in some cases during preliminary studies, by ultrasonic extraction (USE). In ASE, the optimum conditions proved to be two extraction steps at 80 and 140 degrees C (average RSD 10.7%) with three static cycles (extraction time 35 rain) using toluene as solvent and at a pressure of 15 MPa. Owing to the superior analyte/ matrix separation by ASE, in many cases for real soil samples analytical values better by up to 1 order of magnitude or even more were obtained compared to SOX results.
    Keywords: Analytical Chemistry -- Research ; Pollutants -- Research ; Chlorobenzenes -- Research ; Solvents -- Research
    ISSN: 0003-2700
    E-ISSN: 15206882
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  • 3
    In: Analytical Chemistry, July 15, 2001, Vol.73(14), p.3282
    Description: A novel electrochemiluminescence (ECL) detector is presented in this article. The detector is applied for micellar electrokinetic chromatographic separation of dichlorotris(2,2'-bipyridyl)ruthenium(II) hydrate [Ru(bpy)] and dichlorotris(1,10-phenanthroline)ruthenium(II) hydrate [Ru(phen)] on a microfabricated glass device. It consists of a microfabricated "U"-shape floating platinum electrode placed across the separation channel. The legs of the U function respectively as working and counter electrode. The required potential difference for the ECL reaction is generated at the Pt electrode by the electric field available in the separation channel during electrophoretic separation. Initial experiments demonstrate a micellar electrokinetic separation and direct ECL detection of [10.sup.-16] mol of Ru(phen) ([10.sup.-6] M) and 4.5 x [10.sup.-16] mol of Ru(bpy) (5 x [10.sup.-6] M). Also, preliminary results show the indirect detection of three amino acids. The high voltage at the location of detection does not interfere with the electrochemistry.
    Keywords: Electrochemistry -- Research ; Chemiluminescence -- Research
    ISSN: 0003-2700
    E-ISSN: 15206882
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  • 4
    Language: English
    In: The Journal of Physical Chemistry, 12/1993, Vol.97(48), pp.12609-12619
    ISSN: 0022-3654
    E-ISSN: 1541-5740
    Source: American Chemical Society (via CrossRef)
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