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Biomedical subjects

I Bobeldijk

Publications and source records attributed to I Bobeldijk.

10 recordsLinked to original sources
PubMed2006

Dermal, inhalation, and internal exposure to 1,6-HDI and its oligomers in car body repair shop workers and industrial spray painters.

OBJECTIVES: To study inhalation and dermal exposure to hexamethylene diisocyanate (HDI) and its oligomers as well as personal protection equipment (PPE) use during task performance in conjunction with urinary hexamethylene diamine (HDA) in car body repair shop workers and industrial spray painters. METHODS: Personal task based inhalation samples (n = 95) were collected from six car body repair shops and five industrial painting companies using impingers with di-n-butylamine (DBA) in toluene. In parallel, dermal exposure was assessed using nitril rubber gloves. Gloves were submerged into DBA in toluene after sampling. Analysis for HDI and its oligomers was performed by LC-MS/MS. Urine samples were collected from 55 workers (n = 291) and analysed for HDA by GC-MS. RESULTS: Inhalation exposure was strongly associated with tasks during which aerosolisation occurs. Dermal exposure occurred during tasks that involve direct handling of paint. In car body repair shops associations were found between detectable dermal exposure and glove use (odds ratio (OR) 0.22, 95% confidence interval (CI) 0.09 to 0.57) and inhalation exposure level (OR 1.34, 95% CI 0.97 to 1.84 for a 10-fold increase). HDA in urine could be demonstrated in 36% and 10% of car body repair shop workers and industrial painting company workers respectively. In car body repair shops, the frequency of detectable HDA was significantly elevated at the end of the working day (OR 2.13, 95% CI 1.07 to 4.22 for 3-6 pm v 0-8 am). In both branches HDA was detected in urine of approximately 25% of the spray painters. In addition HDA was detected in urine of a large proportion of non-spray painters in car body repair shops. CONCLUSION: Although (spray) painting with lacquers containing isocyanate hardeners results in the highest external exposures to HDI and oligomers, workers that do not perform paint related tasks may also receive a considerable internal dose.

Air Pollutants, Occupational↗
PubMed2005

Determination of kava lactones in food supplements by liquid chromatography-atmospheric pressure chemical ionisation tandem mass spectrometry.

Reversed-phase liquid chromatography and detection with atmospheric pressure chemical ionisation tandem mass spectrometry was used for the determination of kava extracts in herbal mixtures. One percent of kava extract can be detected, corresponding to approximately 0.05-0.2 mg/g of the individual kava lactones kavain, dihydrokavain, yangonin, desmethoxyyangonin, methysticin and dihydromethysticin. Reliable quantification is obtained from concentrations of 0.25-1 mg/g, depending on the compound. At these concentration levels, the relative standard deviations were 10-14%. Validation showed good linearity and recoveries for all the kava lactones with the exception of yangonin. During method development, degradation of yangonin was observed. The degradation product was identified by nuclear magnetic resonance (NMR) as cis-yangonin. The method was applied to the analysis of commercial herbal products available in the Dutch market before and after market restrictions of kava-containing preparations. The results showed that even though 'old' products contained kava extract, the new formulations were negative on kava lactones. cis-Yangonin was also present in the herbal products.

Atmospheric Pressure↗
PubMed2003

Novel monitoring concepts to acquire new water quality knowledge.

Two novel water quality monitoring concepts were developed: the HPLC-fingerprint for the monitoring of yet unidentified pollutants and the HPLC-Toxprint for the recognition of (unknown) toxic or genotoxic compounds. The paper describes applications of both concepts. The HPLC-fingerprint is used for the evaluation of the overall water quality in addition to the monitoring of individual pollutants. Based on their occurrence (frequency, concentration, location) a listing of unknown priority pollutants is set up. Participating waterworks monitor for these compounds using a dedicated HPLC-DAD library that contains the required compound data (UV-absorbance spectrum, retention time index). In five years of experience with this concept, the HPLC-fingerprint was also found very suitable for the retrieval of new priority pollutants in existing HPLC-fingerprint databases, providing historic data on these new compounds. The HPLC-fingerprint concept was also used as an Early Warning System for accidental spills or sabotage. The HPLC-Toxprint was successfully applied in identifying genotoxicity (in the umu-test) in various waste water samples. By the application of LC-MS/MS genotoxicity could be assigned to acridine-derivatives in one of these wastewaters. To enable the evaluation of drinking water resources, the sensitivity of the HPLC-Toxprint was improved, now allowing the detection of pollutants with a 10% genotoxic potential as compared to 2-aminoanthracene (the positive control compound) at concentrations as low as 0.1 microg/l.

Chromatography, High Pressure Liquid↗
PubMed2002

Surface and wastewater quality monitoring: combination of liquid chromatography with (geno)toxicity detection, diode array detection and tandem mass spectrometry for identification of pollutants.

Identification of unknown water pollutants with liquid chromatography and tandem mass spectrometry (LC-MS-MS) is often more complex and time consuming than identification with gas chromatography and mass spectrometry (GC-MS). In order to focus the identification effort on relevant compounds, unknown peaks need to be selected carefully. Based on its frequency of occurrence in the LC-Diode Array Detection (LC-DAD) chromatograms of surface and infiltrated waters, an unknown peak was selected for identification with LC-MS-MS. This compound was identified as hexamethoxymethylmelamine (HMMM), a chemical often used in the coating industry. This is the first time the presence of this chemical in surface waters has been reported. In addition to HMMM, two other structurally related compounds were found to be present in the investigated surface water. A standard mixture of HMMM and its by-products did not exhibit (geno)toxicity under the test conditions applied in this study. In another example, a genotoxic fraction of an industrial wastewater was isolated and examined by LC-MS-MS using a modern quadrupole-orthogonal acceleration-time-of-flight mass spectrometer (Q-TOF). Four compounds were detected. The structures of two compounds present are proposed to be 9-amino-2-hydroxy-acridine and 9-hydroxy-acridine-N-oxide or its structural isomer dihydroxy-acridine. Confirmation with standards could not be carried out, as pure compounds are not available. The other two compounds (structural isomers) could not be identified based on the data available within this study.

Chromatography, High Pressure Liquid↗
PubMed2001

Determination of the herbicide amitrole in water with pre-column derivatization, liquid chromatography and tandem mass spectrometry.

Amitrole is a widely used polar herbicide, difficult to isolate from water. Due to its persistence, it can easily pollute ground and surface waters used in drinking water production. A fully automated on-line SPE-HPLC (solid-phase extraction-high-performance liquid chromatography) method with atmospheric pressure chemical ionisation-tandem mass spectrometry detection is described for the determination of amitrole. A pre-column derivatization with 9-fluorenylmethoxycarbonyl chloride directly in the native aqueous sample allows an enrichment step by SPE and HPLC separation. Due to the sensitivity of tandem mass spectrometric detection, a limit of detection and quantification as low as 0.025 microg/l was achieved in drinking water and ground and surface water. Based on the constant ratio of two selected product ions together with the retention time, the identification is very selective and quantitation is very reliable. The performance characteristics of the described method fully meet the requirements set by the EU Drinking Water Directive: recoveries of >95% in drinking water and >75% in surface water were achieved, as well as RSD values for repeatability of <9% in drinking water and <12% in surface water (determined at a spiking level of 0.1 microg/l). The method was successfully applied to real samples of ground and surface water with actual concentration up to 1.1 microg/l.

Amitrole↗
PubMed2001

Screening and identification of unknown contaminants in water with liquid chromatography and quadrupole-orthogonal acceleration-time-of-flight tandem mass spectrometry.

In order to assess and maintain the quality of surface waters, target compound monitoring is often not sufficient. Many unknown micro-contaminants are present in water, originating in municipal, industrial or agricultural effluents. Some of these might pose a risk to drinking water production and consequently to human health. The possibilities of screening surface water and identification of these non-target water pollutants with modern data acquisition possibilities of hybrid quadrupole-orthogonal acceleration time of flight mass spectrometers (Q-TOF), such as data-dependent MS to MS/MS switching were investigated. Using model compounds, a procedure for the liquid chromatography-tandem mass spectrometry (LC-MS/MS) screening of water extracts was developed, enabling the detection and identification of compounds at levels < or = 0.25 microg/l in surface water. Based on the accurate mass the elemental compositions for the precursor and product ions are calculated. The calculated chemical formulae are searched against the Merck index, the NIST library, an own database containing about 2,500 water pollutants (pesticides and other contaminants) as well as a CI-CID library containing tandem MS spectra of about 100 water contaminants. The developed approach was applied for the identification of unknown compounds, present in native surface water extract. For three of these compounds, structures were proposed. Confirmation of the proposed structures with standards was beyond the scope of this study.

Chromatography, Liquid↗
PubMed2001

High-performance liquid chromatography--ToxPrint: chromatographic analysis with a novel (geno)toxicity detection.

In order to aid the monitoring of the overall quality of (surface) waters a new analytical approach has been developed, combining on-line solid-phase extraction, HPLC separation and effect-related detection. Compounds present in surface water or wastewater samples are extracted on-line with Oasis [poly(divinylbenzene-co-N-vinylpyrrolidone)] material and directly fractionated by reversed-phase HPLC. The eluent of the total chromatogram is collected on a microtitre plate in fractions of 1 min each. After evaporation and re-dissolvation in a suitable solvent, the (geno)toxicity of the individual fractions before and after enzymatic activation with S9, is determined with the umu test. In this way, harmful compounds can be detected and localized in the HPLC-diode array detection trace even without their identity and exact concentration being known at that moment. The method was developed using two test compounds, 4-nitroquinoline-N-oxide and 2-aminoanthracene. Compounds with mutagenic properties comparable to those of the test compounds can be detected from 0.1 microg/l, which is a concentration relevant for surface waters. The new analytical approach was successfully applied to various types of model samples, as well as real wastewater.

4-Nitroquinoline-1-oxide↗
PubMed2001

Screening for transformation products of pesticides using tandem mass spectrometric scan modes.

The applicability of tandem mass spectrometric (MS-MS) scan modes such as constant neutral-loss and precursor-ion scanning to screen for unknown transformation products (TPs) of pesticides at environmentally relevant concentrations (low-microng/l level) is studied. The selection of the MS-MS scan modes is based on the product-ion scan of the parent pesticide, and TPs are detected which are unaltered in the part of the structure concerned. The screening approach is applied to a surface water sample spiked with atrazine and three known TPs at a level of 3 microg/l to study the possibility to extract the TPs from the total ion chromatogram. Next, the approach is used to identify unknown TPs formed after (bio)degradation of two test compounds, fenchlorazole-ethyl (FCE) and furathiocarb (FTC). By using the precursor-ion scan mode, two TPs were detected after biodegradation of FCE, fenchlorazole-methyl and fenchlorazole; in surface water only fenchlorazole was found. The constant neutral-loss scan mode was used to identify carbofuran as TP of FTC. The added value of the proposed procedure is the increased selectivity at the cost of sensitivity. Best results are, therefore, obtained for samples which contain large amounts of matrix constituents.

Pesticides↗