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)
Air Monitoring Method – Translation of the German version from 2022
Ulrich Prott1 (Method development)Ralph Hebisch1 (Head of the working group “Air Analyses” of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft)
Thomas Helmut Brock2 (Head of the working group “Analytics”)
Dietmar Breuer3 (External verification)
Andrea Hartwig4 (Chair of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft)
MAK Commission5
1 Federal Institute for Occupational Safety and Health (BAuA), Friedrich-Henkel-Weg 1–25, 44149 Dortmund, Germany
2 German Social Accident Insurance, Institution for the raw materials and chemical industry, Prevention – Department of Hazardous Substances, Biological Agents and Analytical Chemistry, Kurfürsten-Anlage 62, 69115 Heidelberg, Germany
3 Institute for Occupational Safety and Health (IFA) of the German Social Accident Insurance (DGUV), Alte Heerstraße 111, 53757 Sankt Augustin, Germany
4 Institute of Applied Biosciences, Department of Food Chemistry and Toxicology, Karlsruhe Institute of Technology (KIT), Adenauerring 20a, Building 50.41, 76131 Karlsruhe, Germany
5 Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft, Kennedyallee 40, 53175 Bonn, Germany
Abstract
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%.
