Dicarboxylic acids, short-chained – Determination of oxalic acid, malonic acid, succinic acid, glutaric acid and adipic acid in the workplace air using ion chromatography (IC)

The analytical method described here permits the determination of five linear chain aliphatic dicarboxylic acids with 2 to 6 carbon atoms and terminal carboxy groups occurring as inhalable particles in workplace air. The concentration range covers one tenth up to twice the currently valid Occupational Exposure Limit Value (OELV) in Germany, which is 1 mg/m3 for oxalic acid and 2 mg/m3 for succinic, glutaric and adipic acid (inhalable fraction). The peak limitation with an excursion factor of 2 can also be checked. At the moment, there is no OELV for malonic acid, so the same concentration range has been considered as for oxalic acid. Sampling is performed using a flow-regulated pump to draw a defined volume of air through a glass fibre filter, which is alkaline-impregnated with sodium carbonate and inserted in a GSP sampling system. The volumetric flow rate is 10 l/min. For sampling, 2 hours or 15 minutes can be used. The collected dicarboxylic acid deposited on the filter is extracted by means of an aqueous sodium carbonate/sodium hydroxide solution and analysed by means of ion chromatography using a conductivity detector. Quantitative determination is based on multiple-point calibrations with external standards. For an air sample volume of 1200 litres, the relative limit of quantification (LOQ) is in the range from 0.0002 mg/m3 for oxalic acid and 0.0009 mg/m3 for succinic acid. With LOQs less than 0.0076 mg/m3, the measurement of the short-term exposure limit (STEL) is also enabled with an air sample volume of 150 litres. The recoveries of the five dicarboxylic acids range from 96% to 110% and the expanded uncertainty is less than 29%

Glyphosate – Determination of glyphosate and AMPA in urine by GC-MS/MS

The working group “Analyses in Biological Materials” of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area developed and verified the presented biomonitoring method. Glyphosate (N-phosphonomethylglycine) is a synthetic phosphonic acid derivative which has been used as a broad spectrum herbicide since 1974. Its only known metabolite is aminomethylphosphonic acid (AMPA). Exposure in occupational settings is predominantly due to inhalation and dermal contact with glyphosate. The general population is exposed to glyphosate and AMPA via both dietary (plant and animal products) and environmental (soils, surface water, and groundwater) exposure. The aim of this work was to develop a selective method for the determination of glyphosate and AMPA in urine. The method has been comprehensively validated, and the reliability data have been confirmed by replication and verification of the procedure in a second, independent laboratory. The analytes are directly derivatised in the dried urine sample with trifluoroacetic anhydride and trifluoroethanol without an initial extraction step. Calibration is performed using aqueous calibration standards processed analogously to the samples. As internal standards, glyphosate-d2 and 13C,15N-AMPA are added to the urine samples and calibration standards. The derivatives are measured after capillary gas-chromatographic separation with tandem mass-spectrometric detection (GC-MS/MS) using negative chemical ionisation (NCI). The good precision and accuracy data show that the method provides reliable and accurate analytical results. The method is both selective and sensitive, and the quantitation limit of 0.1 μg/l urine for glyphosate and AMPA is sufficient to determine occupational exposure as well as higher background levels in the general populatio

Comparison of metal-based nanoparticles and nanowires: Solubility, reactivity, bioavailability and cellular toxicity

While the toxicity of metal-based nanoparticles (NP) has been investigated in an increasing number of studies, little is known about metal-based fibrous materials, so-called nanowires (NWs). Within the present study, the physico-chemical properties of particulate and fibrous nanomaterials based on Cu, CuO, Ni, and Ag as well as TiO$_{2}$ and CeO$_{2}$ NP were characterized and compared with respect to abiotic metal ion release in different physiologically relevant media as well as acellular reactivity. While none of the materials was soluble at neutral pH in artificial alveolar fluid (AAF), Cu, CuO, and Ni-based materials displayed distinct dissolution under the acidic conditions found in artificial lysosomal fluids (ALF and PSF). Subsequently, four different cell lines were applied to compare cytotoxicity as well as intracellular metal ion release in the cytoplasm and nucleus. Both cytotoxicity and bioavailability reflected the acellular dissolution rates in physiological lysosomal media (pH 4.5); only Ag-based materials showed no or very low acellular solubility, but pronounced intracellular bioavailability and cytotoxicity, leading to particularly high concentrations in the nucleus. In conclusion, in spite of some quantitative differences, the intracellular bioavailability as well as toxicity is mostly driven by the respective metal and is less modulated by the shape of the respective NP or NW

Chloressigsäuren – Bestimmung von Mono-, Di- und Trichloressigsäure in der Luft am Arbeitsplatz mittels Hochleistungsflüssigkeitschromatographie (HPLC-UV)

This analytical method is a validated measurement procedure for the determination of monochloroacetic acid [79-11-8], dichloroacetic acid [79-43-6] and trichloroacetic acid [76-03-9] in workplace air in a concentration range of one tenth up to twice the currently valid occupational exposure limit values (OELVs) in Germany of 2.0, 1.1 and 1.4 mg/m3, respectively. For sampling, a defined volume of air is drawn through a quartz fibre filter which is alkaline-impregnated with barium hydroxide and inserted in a sampling system for inhalable particles. The flow rate is set to 1 l/min and sampling is performed over 2 hours (which corresponds to a sampling volume of 120 l). The collected chloroacetic acids deposited on the filter are extracted by means of an aqueous phosphate buffer solution and analysed by high performance liquid chromatography with UV detection. Quantitative determination is based on multiple-point calibrations with external standards. For an air sample volume of 120 litres, the relative limit of quantification (LOQ) is in the range from 0.005 mg/m3 for monochloroacetic acid and trichloroacetic acid to 0.002 mg/m3 for dichloroacetic acid. The average recoveries of the three chloroacetic acids range from 88.6% to 101.5% and the expanded uncertainty is less than 29%

Glyphosat – Bestimmung von Glyphosat und AMPA in Urin mittels GC-MS/MS

The working group “Analyses in Biological Materials” of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area developed and verified the presented biomonitoring method. Glyphosate (N-phosphonomethylglycine) is a synthetic phosphonic acid derivative which has been used as a broad-spectrum herbicide since 1974. Its only known metabolite is aminomethylphosphonic acid (AMPA). Exposure in occupational settings is predominantly due to inhalation and dermal contact with glyphosate. The general population is exposed to glyphosate and AMPA via both dietary (plant and animal products) and environmental (soils, surface water, and groundwater) exposure. The aim of this work was to develop a selective method for the determination of glyphosate and AMPA in urine. The method has been comprehensively validated, and the reliability data have been confirmed by replication and verification of the procedure in a second, independent laboratory. The analytes are directly derivatised in the dried urine sample with trifluoroacetic anhydride and trifluoroethanol without an initial extraction step. Calibration is performed using aqueous calibration standards processed analogously to the samples. As internal standards, glyphosate-d2 and 13C,15N-AMPA are added to the urine samples and calibration standards. The derivatives are measured after capillary gas-chromatographic separation with tandem mass-spectrometric detection (GC-MS/MS) using negative chemical ionisation (NCI). The good precision and accuracy data show that the method provides reliable and accurate analytical results. The method is both selective and sensitive, and the quantitation limit of 0.1 μg/l urine for glyphosate and AMPA is sufficient to determine occupational exposure as well as higher background levels in the general population