Collection, validation and generation of bitumen fumes for inhalation studies in rats Part 2: Collection of bitumen fumes from storage tanks.

OBJECTIVES: The objective of the study described in this and an accompanying series of papers was to develop a laboratory generated exposure atmosphere to be used for chronic inhalation toxicity studies in rats that resembles, as closely as possible, personal exposures seen by workers during road paving operations. METHODS: To achieve this objective, atmospheric workplace samples were collected at road paving worksites and compared analytically with bitumen fume samples collected from the headspace of hot bitumen storage tanks. In Preiss et al. (2006) the collection and analysis of workplaces samples is described. This contribution describes the strategy for the in-line extraction of a suitable fraction of bitumen fume collected from the headspace of a bitumen storage tank and the comparison of the collected condensate to workplace samples. RESULTS: Results show that is possible to develop a collecting procedure that allows sampling from hot bitumen storage tanks in an operational asphalt mixing plant. The sampling procedure has been optimized to collect material that matches the workplace samples as closely as possible. The comparison to workplace samples has been performed using parameters that can be analyzed in both the workplace samples and the bitumen fume condensate collected from the tanks. Boiling point distribution (BPD), UV fluorescence (UV-Fl) and content of individual polycyclic aromatic hydrocarbons (PAH) were selected as parameters. The BPD of the final collected bitumen fume condensate did not differ by more than 17 degrees C from any point on the average BPD curve of the workplace samples, in the range from 5 to 95%. UV-Fl of the bitumen fume condensate nearly exactly matched the average UV-Fl of the workplace samples. However, the sum of the 17 PAHs analyzed in the test samples, compared to the mass of the condensate, is lower by a factor of approximately 3 than the sum of the 17 PAHs in some personal samples compared to the mass of Total Organic Matter (TOM). It has to be recognised that during the collection of the workplace samples, despite all efforts a number of the workers who carried a personal sampler could not be prevented from smoking.

Metabolism of verapamil: 24 new phase I and phase II metabolites identified in cell cultures of rat hepatocytes by liquid chromatography-tandem mass spectrometry.

Verapamil is a widely prescribed calcium antagonist, but suffers from extensive first pass metabolism. Despite its frequent use in drug metabolism a complete understanding of its metabolic pathway is still lacking. We thus investigated verapamil's metabolism in cultures of primary rat hepatocytes and isolated metabolites from cell culture media by solid phase extraction (SPE). In detail, we investigated their structure in multiple liquid chromatography-mass spectrometry (LC-MSn) experiments and found 25 phase I and 14 phase II metabolites. We showed many metabolites to be produced by oxidative dealkylation, and several yet unknown metabolites were identified that stem from hydroxylation and dealkylation reactions. Furthermore, we identified an array of glucuronides and, additionally, a glucoside. Finally, we investigated the enantioselective biotransformation of verapamil and found preferential metabolism of the S-enantiomers. In conclusion, this illustrates again the true complexity of verapamil's disposition.

Human biomonitoring of pyrethrum and pyrethroid insecticides used indoors: determination of the metabolites E-cis/trans-chrysanthemumdicarboxylic acid in human urine by gas chromatography-mass spectrometry with negative chemical ionization.

This work describes a gas chromatographic-mass spectrometric method employing negative chemical ionization (NCI) for the determination of E-cis/trans-chrysanthemumdicarboxylic acid (CDCA) in human urine used as a biomarker for the exposure to pyrethrum and/or certain pyrethroids in insecticide formulations applied indoors. Mixed-mode solid phase extraction was utilized for sample cleanup. Extraction recoveries ranged from 92 to 104% (2-9% R.S.D.). The acids were esterified with 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) allowing both their gas chromatographic separation and their sensitive mass spectrometric detection under NCI conditions. Detection limits of ca. 0.05 microg/l urine were achieved.

Verapamil: identification of novel metabolites in cultures of primary human hepatocytes and human urine by LC-MS(n) and LC-NMR.

1. Verapamil is a well-known and world-wide prescribed calcium antagonist, but it suffers from extensive first-pass metabolism. Although it has been marketed for many years, a complete understanding of its biotransformation in humans is still lacking. 2. The metabolism of verapamil was therefore investigated in cultures of primary human hepatocytes and in extracts of human urine after oral dosing. Identification of metabolites was done with LC-MS(n) and LC-NMR (600 MHz) to obtain in-depth information on its biotransformation products and definitive proof of the proposed chemical structures of metabolites. 3. Hyphenation of LC-MS(n) and LC-NMR was shown to be a powerful and effective platform for the identification of metabolites. Indeed, 21 Phase I and 16 Phase II metabolites were identified. Basically, all the Phase II metabolites (glucuronides) and 11 of the Phase I (oxidative) metabolites were not reported previously. 4. New insight into verapamil's biotransformation pathway is provided as well as evidence about its true complexity of metabolic disposal.

Development of a gas chromatography-mass spectrometry method for the determination of household insecticides in indoor air.

This work presents a GC-MS method for the determination of 17 household insecticides and acaricides in indoor air. Air samples were collected with a sampling train which consisted of a glass fibre filter and two polyurethane foam plugs, followed by a high-volume air pump. Filters and plugs were analysed separately. The overall recoveries ranged from 85 to 109% (4-11% RSD). Minimum method detection limits between 0.1 and 5 ng/m3 were determined.

Verapamil drug metabolism studies by automated in-tube solid phase microextraction.

Verapamil is a common calcium antagonist described with antianginal, antihypertensive and antiarrythmic properties. The metabolites of verapamil have also shown pharmacological properties and therefore sample preparation and analysis techniques capable of metabolic screening for verapamil are important. In-tube SPME is a relatively new method integrating sample extraction, concentration and introduction into one single step without the use of organic solvents. The capability of in-tube SPME in bioanalysis has been reviewed but there has been no application described in the field of drug metabolism. Since automation and interfacing of in-tube SPME coupled to liquid chromatography-mass spectrometry (LC-MS) is possible, we confirm in this study that it is a powerful method to monitor the main metabolites of verapamil in various biological matrices like plasma, urine and cell culture media. Further, we show that it could also be used in routine pharmacokinetics measurements. An in-tube SPME LC-MS method was developed to extract and analyze the metabolic profile of verapamil from biological matrices. The detection limit for verapamil, gallopamil, norverapamil and PR22 were 52, 53, 65 and 83 ng/ml (UV detection) and 5, 6, 6 and 8 ng/ml (MS detection), respectively. The precision of the method was calculated in various biological matrices and the average % R.S.D. (N=5) for verapamil, gallopamil, norverapamil and PR22 was 3.9, 3.7, 3.8 and 4.3% (MS detection), respectively. The linear dynamic range was determined to be 100-800 ng/ml (UV detection) with a total sample preparation and analysis time of 34 min.

Combination of matrix solid-phase dispersion extraction and direct on-line liquid chromatography-nuclear magnetic resonance spectroscopy-tandem mass spectrometry as a new efficient approach for the rapid screening of natural products: application to the total asterosaponin fraction of the starfish Asterias rubens.

A combination of matrix solid-phase dispersion extraction (MSPD) and LC-NMR-MS hyphenation is proposed as a rapid screening method of natural products for unknown compounds. In this report, this new analytical approach is applied for the first time. MSPD represents a significant simplification compared to classical extraction procedures and is thus an excellent complement to the fast and powerful LC-NMR-MS: MSPD yields extracts suitable for LC-NMR-MS in one simple preparation step, while LC-NMR-MS yields a wealth of information in one single chromatographic run. The suitability of this technique to characterise glycosidic compounds in the molecular mass range of 1200 to 1400 a.m.u. is demonstrated. The information on the number of exchangeable protons provided by an additional back-exchange experiment proved to be particularly valuable for structural elucidation. The possibility of semi-quantitative LC-NMR measurements through methyl signals H(3)-18 and 19 of the steroidal skeleton is demonstrated and is ensuingly used to provide relative quantitative data of the steroid oligosaccharide fraction.

Verapamil metabolism in distinct regions of the heart and in cultures of cardiomyocytes of adult rats.

A substantial number of drugs act either directly or indirectly on the heart, but surprisingly, little is known about drug oxidation in the heart. We therefore investigated the metabolism of the calcium antagonist verapamil in microsomal fractions isolated from the left and right ventricle of heart muscle and in primary cultures of cardiomyocytes of adult rats. Metabolism of verapamil proceeded predominantly with microsomal fractions isolated from the right ventricle of rat heart, and in liquid chromatographic-tandem mass spectrometry (LC-MS/MS) and LC-MS(3) experiments four metabolites (M1-M4) could be identified. Furthermore, the intermediate biotransformation products M5 to M8 could additionally be identified in cultures of primary cardiomyocytes, thus providing new insight into the mechanisms of the N-dealkylation and O-demethylation pathway of verapamil. We show metabolism of verapamil to be predominant in the right ventricle of the heart, and the data reported herein may explain metabolic inactivation and/or adverse drug reactions of certain cardiovascular drugs on the basis of tissue specific metabolism.

Characterization of dyes and other pollutants in the effluent of a textile company by LC/NMR and LC/MS

LC/NMR and LC/MS (the latter technique in the MSn mode) were used to characterize the organic constituents of industrial wastewater with emphasis on polar, nonvolatile compounds. In the effluent of a textile company, various compounds such as anthraquinone-type dyes and their byproducts, a fluorescent brightener, a byproduct from polyester production, and auxiliaries such as anionic and nonionic surfactants and their degradation products were identified. It is shown that the combined use of both hyphenated techniques provides complementary structural information. If applied under comparable chromatographic conditions, they are well-suited for the nontarget analysis.

Bioavailability of fine dispersed platinum as emitted from automotive catalytic converters: a model study.

Automobile exhaust catalytic converters emit fine dispersed elemental platinum, Pt (0), in the nanometer range coated on larger aluminium oxide carrier particles. A pre-requisite for a potential systemic toxic effect of the emitted platinum is its bioavailability which was investigated using laboratory animals. To this end, a model substance was synthesised which consisted of aluminium oxide particles < or = 5 microns onto which platinum particles > or = 4 nm were deposited by a calcination process. These particles closely resemble those emitted from automobile exhaust converters. This model substance was applied to female Lewis rats in two doses by intratracheal instillation; the animals were killed after 1, 7, 28 and 90 days. In addition, the model substance was also applied during a 90-day inhalation study. After microwave digestion of the tissues, the platinum was determined in all organs and body fluids by inductively coupled plasma/mass spectrometry (ICP/MS). Platinum was found in the blood, urine and faeces and all important organs (liver, spleen, kidneys, adrenals, stomach, femur). Based on the platinum content determined in the body fluids and all organs (except the lung and the faeces) it was calculated that up to 16% of the platinum was retained in the lung 1 day after intratracheal instillation and up to 30% of the fine dispersed platinum deposited on an average during 90 days inhalation in the lung was bioavailable. Using size exclusion chromatography (SEC) in combination with ICP/MS, it was shown that > or = 90% of the bioavailable platinum was bound to high molecular weight compounds (approximately 80-800 kDa), most likely proteins.

Comparative studies of the leachate of an industrial landfill by gas chromatography-mass spectrometry, liquid chromatography-nuclear magnetic resonance and liquid chromatography-mass spectrometry.

Nowadays, the need to have a realistic characterization of industrial effluents in the environment has become more and more recognized. A palette of different analytical methods both for sample extraction and instrumental analysis are available today, some older, others introduced more recently. The aim of this research is to compare a number of these techniques. To do this we studied a real leachate from an industrial landfill and carried out chemical analyses for organic pollutants, using different extraction methods based on solid-phase extraction and solid-phase microextraction and different instrumental techniques such as GC-MS, LC-MS, NMR and LC-NMR. Results show the performances of the different techniques, which are complementary.

Application of Continuous-Flow HPLC-Proton-Nuclear Magnetic Resonance Spectroscopy and HPLC-Thermospray-Mass Spectroscopy for the Structural Elucidation of Phototransformation Products of 2,4,6-Trinitrotoluene.

An aqueous solution of 2,4,6-trinitrotoluene (TNT) was irradiated by natural sunlight for a period of 1 month to generate phototransformation products of this compound. After solid-phase extraction on a poly(styrene-divinylbenzene) copolymer at pH 1, the structures of several acidic nitroaromatic compounds were identified by means of continuous-flow HPLC/(1)H NMR and HPLC/TSP-MS measurements of this extract. By interpretation of both NMR and MS spectra, it was even possible to characterize noncommercially available phototransformation products of TNT. The results obtained by continuous-flow HPLC/(1)H NMR were compared with those obtained by the investigation of a groundwater sample of a former ammunition site near Elsnig, Germany. The results show that several identified phototransformation products of TNT are also present in this groundwater sample.

Pesticides in rain.

40 rainwater samples were collected in Hannover and near Peine (Lower Saxony, Germany) in 1992 using a wet-only collector. The samples were extracted by solid phase extraction and analyzed by GC/MS for 59 pesticides. 11 pesticides were found in more than 10 samples. The highest concentrations were observed for terbuthylazine (0.003-0.52 microgram/L), metolachlor (0.003-0.51 microgram/L, mean: 0.10 microgram/L), metalaxyl (0.006-0.48 microgram/L, mean: 0.10 microgram/L) and chlorothalonil (0.003-1.1 micrograms/L, mean: 0.16 microgram/L). The concentrations show a seasonal dependence reflecting the application periods.

Application of high-field proton nuclear magnetic resonance ((1)H-NMR) spectroscopy for the analysis of explosives and related compounds in groundwater samples - a comparison with the high-performance liquid chromatography (HPLC) method.

High-field proton nuclear magnetic resonance ((1)H-NMR) spectroscopy was applied to the analysis of nitroaromatics and nitramines in ammunition waste water. The (1)H-chemical shifts data of a variety of reference compounds are presented. Three groundwater samples, taken near the former ammunition plant Elsnig (Saxony), were analysed by high-performance liquid chromatography (HPLC) and by proton nuclear magnetic resonance spectroscopy. The results of HPLC and NMR analyses are compared and discussed.

Platinum solubility of a substance designed as a model for emissions of automobile catalytic converters.

Automobile catalytic converters emit nanocrystalline platinum attached to alumina particles. For investigations about the bioavailability of Pt from these particles a model substance with approx. 5% Pt on alumina has been prepared and characterized by physical methods (ESCA, XRD, TEM, DTA, TG). Measuring the platinum solubility of these samples in different solvents revealed high amounts that can be explained assuming a corrosion process. The portion of soluble platinum is dependent on the particle size distribution. For a comparative study platinum black has been used. In general the platinum determination has been carried out by electrothermal atomic absorption spectrometry (ET-AAS). The comparison of ET-AAS results with determinations by adsorptive voltammetry (formazone method) allowed to distinguish between elemental and ionic platinum; in solution samples only ionic platinum has been present. UV spectra of extracts have been used for the semi-quantitative platinum speciation in solutions.

Determination of pesticides in aqueous samples by solid-phase microextraction in-line coupled to gas chromatography-mass spectrometry.

A multiresidue method was developed for the determination of nitrogen- and phosphorous-containing pesticides (amines, anilides, phosphorothioates, and triazines) by solid-phase microextraction (SPME) in-line coupled to gas chromatography-mass spectrometry (GC/MS). The 85-µm polyacrylate fiber was first dipped into the aqueous sample for a given time and then directly introduced into the heated injector of the gas chromatography-mass spectrometer, where the analytes are thermally desorbed. The method was evaluated with respect to the limit of detection, linearity, and precision. The limit of detection [selected ion monitoring (SIM) mode] depends on the compound and varies from 5 to 90 ng/L. The method is linear over at least 3 orders of magnitude with coefficients of correlation usually ≥0.996. In general, the coefficient of variation (precision) is <10%. The partitioning of the analyte between the aqueous phase and the polymeric phase depends on the hydrophobicity of the compound as expressed by the octanol-water partitioning coefficient P ow. The addition of sodium chloride has a strong effect on the extraction efficiency. This effect increases with decreasing hydrophobicity (increasing polarity) of the compound.The triazines atrazine, simazine, and terbuthylazine were first identified and quantified in water samples from the effluent of sewage plants by SPME-gas chromatography-nitrogen-phosphorus detection (GC/NPD). For such a complex matrix GC/NPD is not sufficiently selective for an unambiguous identification at low levels (<1 ppb) of pesticides. Selectivity may be enhanced by using SMPE-GC/MS in the SIM mode with three characteristic ions for each pesticide. This method allows an unequivocal identification and quantification at low levels of pesticides in environmental samples.At a target limit of detection below 100 ng/L, SPME-GC/MS represents a very simple, fast, selective, and solvent-free multimethod for the extraction and determination of these nitrogen- and phosphorous-containing pesticides from aqueous samples.

Comparative study of different thermospray interfaces with carbamate pesticides: Influence of the ion source geometry.

Sixteen carbamate pesticides that belong to four chemical classes (oxime-N-methylcarbamates, aryl N-methylcarbamates, N-phenylcarbamates, and methyl esters of substituted carbamic acids) were investigated via three different commercially available thermospray interfaces and ion sources that exhibit wide differences in source geometry. Comparisons were made between the three interfaces with respect to ion formation and sensitivity of detection. Experimental parameters were standardized to obtain comparable experimental conditions. Very similar mass spectra for most carbamates were obtained that illustrate independence from the geometry of the ionization and desolvation chambers of the interfaces. These findings are in sharp contrast to several literature reports. However, thermally labile carbamates gave unsatisfactory results with regard to spectral compatibility between the interfaces. Such differences were due to thermally assisted hydrolysis reactions that occur in the vaporizer probe prior to ionization and reflect differences in the vaporizer designs. The study proves conclusively that comparable spectra can be obtained under thermospray with different interfaces and mass spectrometers.

Mass spectrometric analysis of nitrogen- and phosphorus-containing pesticides by liquid chromatography-Mass Spectrometry.

A series of nitrogen- and phosphorus-containing pesticides (amines, anilides, carbamates, phosphonates, phenylureas, sulfonylureas, and triazines) was examined by thermospray (TSP) ionization. A method is described that employs off-line and on-line solid-phase extraction and TSP liquid chromatography-mass spectrometry (LC-MS) with time-scheduled selected ion monitoring (SIM) for environmental monitoring of these pesticides in aqueous samples. SIM detection limits for the pesticides analyzed in conjunction with reversed-phase high-performance liquid chromatography range from 40 to 600 pg. In addition, methods for inducing fragmentation in thermospray LC-MS are presented. The structural information gained therefrom can be used to confirm a tentative identification. Therefore, fragmentation pathways under certain experimental conditions were investigated. Atmospheric pressure chemical ionization, electrospray, fast-atom bombardment, (252)Cf plasma desorption, and collision-activated dissociation spectra are presented for several pesticides to confirm the proposed pathways and to gain additional and complementary information. Further confirmation may be achieved by postcolumn addition of different alkylated amines to the carrier stream in the TSP operation to induce postcolumn on-line derivatization (POD) reactions in the condensed phase of the vaporizer probe with selected pesticides. Additional clustering reactions in combination with solvent-mediated chemical ionization are observed by the POD technique. Both processes can be used to enhance the structural information from TSP spectra and thus the specificity of the method.

[The behavior of fiber-reinforced plastics during laser cutting]. / Das Verhalten faserverstärkter Kunststoffe beim Laserschneiden.

The pattern of the organic emissions, which are produced by processing of fibre reinforced plastics (epoxy resins reinforced by aramid and glass fibres and phenol resins reinforced by aramid fibre) with laser beam was studied and the concentrations of the main components determined. Despite the application of plastic materials with different chemical structures, the observed patterns are very similar. Mainly aromatic hydrocarbons are emitted, especially benzene and toluene, as well as some heteroatom-containing aromatic hydrocarbons (e.g. phenol). By use of oxygen as process gas the emissions during cutting of glass fibre reinforced plastics can be reduced, while they will be constantly high with aramid fibre reinforced plastics.

Gas chromatographic and mass spectrometric determination of nitroaromatics in water.

Several methods for the extraction of nitroaromatic compounds from water were compared. High recoveries were achieved with discontinuous or continuous extraction of water with dichloromethane and by adsorption on Amberlite XAD-2, -4 and -8 resins (1:1:1) and elution with dichloromethane. The recoveries obtained with solid-phase extraction using cyano-, phenyl- or octadecyl-bonded phases varied, depending on the compounds studied, and were often low. Nitroaromatic compounds were determined by gas chromatography using an electron-capture or a chemiluminescence detector (thermal energy analyser) and by mass spectrometry using electron impact and positive- and negative-ion chemical ionization.