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Analytical and Bioanalytical Chemistry (v.366, #4)
A new sample preparation technique for organochlorines in cod liver oil combining SPE and NP-HPLC with HRGC-ECD by M. W. Arend; K. Ballschmiter (pp. 324-328).
The analysis of semivolatile organochlorines (polychlorinated biphenyls and chlorinated pesticides) in less polluted biomaterials requires specific strategies in controlling the blank in sample preparation. The procedure described here allows to decrease significantly the level of contamination during the clean-up step of fish oil. Solid-phase-extraction (SPE) on LiChrolut® EN and normal phase HPLC in the normal- and the backflush-mode were used to reduce the amount of solvents needed and the analysis time compared to established clean-up procedures. With a certified reference material (BCR-CRM 349; Cod Liver Oil) the precision and effectiveness of the new method were validated. Recovery rates of the Internal Standards (PCB 103 and TCN) lay between 75% and 90% at the μg/kg lipid level. The quantitative analyses were carried out by high resolution gas chromatography with electron capture detector (HRGC-ECD).
Surface characterization of commercial fibers for solid-phase microextraction and related problems in their application by C. Haberhauer-Troyer; M. Crnoja; E. Rosenberg; M. Grasserbauer (pp. 329-331).
The surfaces of commercially available polydimethylsiloxane (PDMS) and Carboxen-PDMS fibers for solid-phase microextraction (SPME) were investigated by optical and electron microscopy. Damage to the coating as well as contamination of new fibers and a highly variable number of pores in Carboxen-PDMS coatings were observed. Together with the contamination of the fibers during their use with metallic particles originating from the SPME fiber holder they are possible explanations for the problems encountered in the analysis of organolead, organotin and organosulfur compounds, such as artifact formation and low repeatability.
Automized procedures for the determination of ozone and ammonia contents in air by using the chromatomembrane method for gas-liquid extraction by H. Erxleben; J. Simon; L. N. Moskvin; L. O. Vladimirovna; T. G. Nikitina (pp. 332-335).
Chromatomembrane cells (CMC) operate as unique manifolds for extraction and preconcentration procedures in computer controlled flow-injection-analysis (FIA). By coupling to an ion chromatograph and to a conductometer, respectively, instrumentation is obtained that allows the pretreatment and the detection of ozone- and ammonia-containing samples after absorption of the gaseous constituents of air inside a chromatomembrane cell. The analysis of air even in the presence of liquid aerosols is discussed.
Transport processes through track-etch membrane filters in a reagent delivery cell by S. Rzepka; B. Neidhart (pp. 336-340).
A reagent delivery cell with a track-etch membrane filter for on-line dilution of concentrated salt solutions is described. The influence of several system parameters such as concentration of the stock solution, temperature, transmembrane pressure and the dependence on the diffusion coefficients of several salt components on the dilution was evaluated. As an application example, the use of the reagent delivery cell for on-line calibration of an atomic absorption spectrometer was studied. Fluxes through the membrane filter of 10 to 50 nL mm–2 min–1 with relative standard deviations of 0.8% within a day and 1.9% from day to day were achieved. The permeation experiments with the track-etch membrane filter for the dilution of aqueous solutions of several chlorides and sodium salts confirm a diffusion process. Flux rates can be estimated mathematically using Fick’s first law with an agreement between measured and calculated dilution factors within 86 to 113%.
Spacer-modified stationary phases for anion chromatography: Alkyl- and carbonylalkylspacers – A comparison by M. Nowak; A. Seubert (pp. 341-345).
A comparison of two separation columns for high-capacity anion chromatography is presented. The distinctive feature of both packing materials is the structure of the alkyl-chain (spacer-group) between the polymer-backbone and the functional group. All other parameters, e.g. exchange capacity, functionality and length of the spacer-arm, are identical. The retention behavior of the so-called standard-anions is investigated on both columns under identical chromatographic conditions using an experimental design technique in the course of which the composition of the elution system applied is varied. The statistical treatment of the retention data offers the possibility to explain the different chromatographic behavior of both stationary phases, at least qualitatively.
New stationary phase based on β-cyclodextrin for normal-phase HPLC group-separation of organic nitrates by M. Wößner; K. Ballschmiter (pp. 346-350).
The synthesis of a β-cyclodextrin-silica normal-phase (NP)-liquid chromatography (LC) stationary phase is reported. Silica gel was modified with (3-bromopropyl)trimethoxysilane to a 3-bromopropyl-silica that was reacted with β-cyclodextrin, resulting in a β-cyclodextrin-silica. To prove its usefulness in group-separation of organic nitrates among others, a mixture of three groups of organic nitrates was separated. The results are compared with those obtained on a nitrated polyol-silica that has recently been reported. The alkyl dinitrates exhibt higher retention relatively to alkyl mononitrates on the new phase. This allows to cut the LC fractions in a way that the alkyl mononitrates and phenylalkyl nitrates appear in one fraction and the dinitrates in a second one without any overlap of the two fractions.
Influence of column geometry on the ion chromatographic separation of aluminium species by M. Busch; A. Seubert (pp. 351-355).
The dependence of the degree of disintegration and therefore the applicability of ion chromatography for the speciation of aluminium fluoride species was examined for two different column geometries, a standard bore and a microbore column. Besides mathematical calculations, the temperature of the separation column was varied between –5 and 50 ˚C for the observation of a temperature-dependent decomposition of the species. All species were detected by UV photometry after post-column reaction with Tiron. The results showed that the disintegration of the higher coordinated Al fluoride species (AlFn with n >2) could be dramatically reduced utilizing the microbore technique. In contrast to the standard bore technique the column temperature is of minor importance. The agreement between speciation data experimentally determined by microbore chromatography and those calculated using stability constants is quite good. The standard bore technique showed bigger differences between calculated and experimentally determined species distributions.
Comparison of sodium tetraethylborate and sodium tetra(n-propyl)borate as derivatization reagent for the speciation of organotin and organolead compounds in water samples by P. Schubert; E. Rosenberg; M. Grasserbauer (pp. 356-360).
The influence of pH on the propylation with sodium tetra(n-propyl)borate of butyl- and phenyltins as well as for trimethyl- and triethyllead was investigated. Ethylation and propylation with tetraalkylborates were compared with regard to derivatization yields and figures of merit for organotin compounds in real water samples. Similar results for limit of detection (3–12 ng/L as tin), derivatization yield (40–100%) and relative standard deviation of the method (3–10%) were achieved for derivatization with the two tetraalkylborates. Propylation is thus the preferred method for the simultaneous determination of environmentally relevant organotin and organolead compounds. The handling of the hygroscopic and air sensitive reagents NaBEt4 and NaBPr4 was simplified by dissolving them in tetrahydrofurane. The reagent solutions in tetrahydrofurane can be stored for at least one month at ¶4 °C in the dark without observing any decrease in the derivatization efficiency.
Spectrophotometric and direct-reading methods for the analysis of gas phase peroxyacetic acid by S. Effkemann; S. Brødsgaard; P. Mortensen; S.-A. Linde; U. Karst (pp. 361-364).
A new method for the determination of peroxyacetic acid (PAA) in gas phase samples is described. It is based on the oxidation of ABTS (2,2′-azino-bis(3-ethylbenzothiazoline)-6-sulfonate) by PAA with formation of a radical cation which is characterized by four strong absorption maxima between 405 nm and 810 nm. These allow for sensitive spectrophotometric determination of the peracid. The selectivity of the method towards hydrogen peroxide is strongly dependent on the sampling method used. Impinger sampling and sampling based on the use of coated solid sorbents (test tubes) was performed. Limits of detection are 10–8 mol, limits of quantification are ¶5 × 10–8 mol, the linear range consists of 1.5 concentration decades in both cases. Using ABTS-coated test tubes above 1 × 10–7 mol, direct reading of the results is possible and may be used as rapid screening method for the PAA concentration.
Analysis of halogenated C1/C2-trace compounds in marine atmosphere by T. Urhahn; K. Ballschmiter (pp. 365-367).
Patterns of volatile ECD-active substances in marine air at the ultra trace level were investigated. The protocol used carbon based adsorbents, thermodesorption and thick film HRGC-ECD together with a second ECD in line with oxygen doped make-up gas. The latter ECD mode leads to an increased sensitivity for chloromethane, dichloromethane, and other important chlorinated substances with an otherwise low response at an ECD driven with oxygen-free nitrogen or argon/methane. The experimental set-up is easily to employ. Air samples were taken on two cruises of the German research vessel R/V “Polarstern” in the Atlantic Ocean to determine the background pattern of all volatile halocarbons from CF3Cl to CHI3 in marine air.
Direct observation of the formation of aromatic pollutants in waste incineration flue gases by on-line REMPI-TOFMS laser mass spectrometry by R. Zimmermann; H. J. Heger; A. Kettrup; U. Nikolai (pp. 368-374).
On-line REMPI-TOFMS laser mass spectrometry (Resonance Enhanced Multi-Photon Ionization – Time-Of-Flight Mass Spectrometry) was used to monitor combustion and pyrolysis byproducts from industrial combustion processes, including polycyclic aromatic hydrocarbons (PAH) and monochlorobenzene in the flue gas of an industrial 22 MW hazardous waste incineration plant. Sampling at different places in the flue gas stream revealed the complexity of the processes responsible for the formation of the different chemical species, while time resolved measurements depicted the emission dynamics.
Analysis of the cancerogenic heterocyclic aromatic amines in fried meat by M. Murkovic; W. Pfannhauser (pp. 375-378).
Heterocyclic aromatic amines (HAs) are potential cancerogens found in heated meat and fish. From the precursors creatin/ine amino acids and carbohydrates the HAs are formed in very complex reactions at high temperatures. The concentration in meat is very low and the analysis especially the clean-up is critical due to the complex meat matrix. The concentrations in heated meat are in the low ng/g range. With increasing time of heating and the temperature the concentration of the HAs (MeIQx, IQ, 4,8-DiMeIQx, PhIP) can increase from 0 to 5 ng/g at ¶140 °C for 15 min to 20 to 40 ng/g at 220 °C for 35 min. MeIQ is formed at a significant lower amount.
Analysis of anthocyane glycosides in human serum by M. Murkovic; U. Adam; W. Pfannhauser (pp. 379-381).
Anthocyanins, natural food antioxidants, can be identified in human blood plasma using a restricted access phase for removal of the proteins and enrichment of the anthocyanins. In preliminary studies the spray dried elderberry juice was shown to have antioxidant activities in vitro. From the four known anthocyanins present in elderberry (Sambucus nigra) the two main components could be analysed quantitatively enabling their analysis in blood. Using a restricted access phase and a column switching set-up the injection of high volumes of concentrated protein solutions is possible. Additional, by using high injection volumes the sensitivity is increased due to a concentration of the analytes on the restricted access phase. The limit of quantification reached was 0.5 ng/mL. In this experiment the maximum concentration in blood (35 mg/mL) was observed after 1 h with a quick decay.
Quantification of β-trace protein and detection of transferrin isoforms in mixtures of cerebrospinal fluid and blood serum as models of rhinorrhea and otorrhea diagnosis by T. O. Kleine; T. Damm; H. Althaus (pp. 382-386).
Different mixtures from a serum pool and a cerebrospinal fluid (CSF) pool were used as models to study CSF contamination in secretions by determining two CSF specific proteins: β-trace protein (β-TP) and the asialo-transferrin (a-Tf) band which was detected by isoelectric focusing (IEF) with Tf specific immunofixation. β-TP and total Tf were measured immunonephelometrically. Secretion/serum ratios of β-TP content > 2.0 indicated CSF contaminations with ≥ 5% (v/v) CSF; this was confirmed by detecting the a-Tf band by IEF. Reliable ¶a-Tf bands were only revealed with secretion/serum rations of Tf contents < 0.1, indicating an interference of major sialo-Tf fractions with the a-TF band detection in the sample. For CSF detection in rhinorrhea and otorrhea, complementary use of β-TP assay and a-Tf assay is recommended. Preanalytically, dilution or concentration of the sample as well as denaturation of Tf and β-TP should be prevented by optimizing sample collection.
Comparison of ion chromatographic methods based on conductivity detection, post-column-reaction and on-line-coupling IC-ICP-MS for the determination of bromate by G. Schminke; A. Seubert (pp. 387-391).
An established method for the determination of the disinfection by-product bromate is ion chromatography (IC). This paper presents a comparison of three IC methods based on either conductivity detection (IC-CD), a post-column-reaction (IC-PCR-VIS) or the on-line-coupling with inductively coupled plasma mass spectrometry (IC-ICP-MS). Main characteristics of the methods such as method detection limits (MDL), time of analysis and sample pretreatment are compared and applicability for routine analysis is critically discussed. The most sensitive and rugged method is IC-ICP-MS, followed by IC-PCR-VIS. The photometric detection is subject to a minor interference in real world samples, presumably caused by carbonate. The lowest sensitivity is shown by the IC-CD method as slowest method compared, which, in addition, requires a sample pretreatment. The highest amount of information is delivered by IC-PCR-VIS, which allows the simultaneous determination of the seven standard anions and bromate.
Determination of endogenous and exogenous estrogens in effluents from sewage treatment plants at the ng/L-level by H. M. Kuch; K. Ballschmiter (pp. 392-395).
An analytical method for the determination of the major endogenous and exogenous estrogenic steriods in effluent water samples of sewage treatment plants (STPs) with a LOQ down to 1 ng/L and below has been developed. The exogenous estrogen 17α-ethynylestradiol, frequently used as estrogenic component in oral contraceptives, and the endogenous estrogen 17β-estradiol show the highest estrogenic potential, therefore they were part of our target compounds. In addition, the content of the synthetic gestagen levonorgestrel, also often administered in oral contraceptives, was determined. A solid-phase extraction system for high volume sampling of water up to 25 L was implemented. Two types of adsorbent, Amberlite XAD 2 and a mixture of LiChrolut EN/Bondesil C-18, respectively, were tested for their extraction efficiency of these polar analytes. Recovery rates with LiChrolut EN/¶Bondesil C-18 ranged up to 94 %, whereas sampling on XAD 2 led only to poor recoveries below 40 %. After a liquid chromatographic clean-up step on silicagel the steroids were converted into their trimethylsilyl-ethers by the reaction with MSTFA/TMSI (N-methyl-N-trimethylsilyl-2,2,2-trifluoroacetamide, trimethylsilyliodide) and were then determined by HRGC/MS in the selected ion mode. A limit of quantification over the whole procedure of at least 1 ng/L was reached for all analytes. In several effluent samples the input of estrogens by the STP of the cities Ulm and New Ulm into the river Danube was characterised. The concentrations commonly found ranged from 1 ng/L up to 13 ng/L, depending on the respective steroid.
Determination of acetaldehyde in tobacco smoke using N-methyl-4-hydrazino-7-nitrobenzofurazan and liquid chromatography/mass spectrometry by G. Zurek; A. Büldt; U. Karst (pp. 396-399).
A liquid chromatography/mass spectrometry (LC/MS) method for the determination of carbonyl compounds based on derivatization with N-methyl-4-hydrazino-7-nitrobenzofurazan (MNBDH) has been developed. Atmospheric pressure chemical ionization (APCI) in the positive mode proved the most versatile ionization technique for MNBD-hydrazones. APCI/MS spectra were recorded and the detection limits were determined for [M+H]+. 13C2 acetaldehyde MNBD-hydrazone has been synthesized and characterized. It is applied as internal standard for the quantification of acetaldehyde. Tobacco smoke has been investigated concerning its carbonyl content. Acetaldehyde was identified as main product and quantified by LC/MS using internal standardization. The result is in good agreement to quantification data obtained with UV/vis detection.
Investigating the potential of high-performance liquid chromatography with atmospheric pressure chemical ionization-mass spectrometry as an alternative method for the speciation analysis of organotin compounds by E. Rosenberg; V. Kmetov; M. Grasserbauer (pp. 400-407).
Liquid chromatography with atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) was applied for the determination of butyl- and phenyltin compounds. Chromatography was performed on a 30 ׶2 mm, 3 μm C18 column, enabling the separation of mono-, di- and trisubstituted butyl- and phenyltin compounds in less than 10 min using a water/1% trifluoroacetic acid/¶methanol gradient. While satisfactory retention and resolution is achieved for the di- and trisubstituted butyl- and phenyltin compounds, monobutyltin and monophenyltin cannot be resolved chromatographically. Depending on the parameter values of the interface, APCI-MS detection allows both specific detection of the molecular ion or cluster ion at low to intermediate fragmentor voltages or quasi-element specific detection of the Sn+ ion released from the organotin compounds at high fragmentor voltages. The sensitivity of MS detection is similar for butyl- and phenyltin compounds, but varies largely from mono- to trisubstituted organotin compounds with tributyl- and triphenyltin being the most sensitively detectable compounds. Detection limits are in the 20–65 pg (abs.) range in SIM mode and in the 750–2000 pg (abs.) range in the scan mode for tributyl- and triphenyltin and for dibutyl- and diphenyltin, respectively. Monobutyl- and monophenyltin can be detected with much lower sensitivity which, together with their unfavorable chromatographic behavior, accounts for the fact that they cannot be analyzed at environmentally relevant concentrations. Although LC-APCI-MS is generally less sensitive than comparable GC methods, it is applicable to the analysis of environmental samples as demonstrated by the analysis of the PACS-2 sediment certified reference material. Although the derivatization of the ionic organotin compounds, which particularly in real samples is a potential source of error, is circumvented when LC-APCI-MS is used, the extraction step is still critical and may lead to underestimation when quantitation is not done by the method of standard addition.
On-line and in-situ detection of polycyclic aromatic hydrocarbons (PAH) on aerosols via thermodesorption and laser-induced fluorescence spectroscopy by U. Panne; A. Knöller; R. Kotzick; R. Niessner (pp. 408-414).
A fiber optical sensor system for the determination of polycyclic aromatic hydrocarbons (PAH) on aerosols by laser-induced, time-resolved fluorescence is combined with a thermodesorption device. The sensor system is based on an aerosol flow cell, which is fibre-optically coupled to a pulsed nitrogen laser for excitation and the detection system. Time-resolved fluorescence emission spectra are detected by a monochromator equipped with a photomultiplier and a fast digital storage oscilloscope. The analytical figures of merit of the thermodenuder are reported for benzo[a]pyrene, benzo[b]fluoranthene, and benzo[ghi]-perylene on ultrafine soot and NaCl aerosols. By thermodesorption of the PAH, problems due to quenching of the PAH fluorescence by the bulk aerosol material or excimer formation on the aerosol surface were avoided. For the PAH under study, the sensitivity was improved considerably and detection limits between 110 and 850 ng m–3 were attained, while a response time of 2–3 min was achieved with the thermodenuder. A calibration for PAH on ultrafine soot and NaCl aerosols was established independent of the aerosol substrate.