(in German)

The analytical method described here permits the determination of methanesulfonic acid [75-75-2] occurring as inhalable particles and vapour in workplace air. The concentration range covers one tenth up to twice the currently valid Occupational Exposure Limit Value (OELV) in Germany of 0.7 mg/m³ (inhalable fraction). The short-term exposure limit (STEL) with an excursion factor of 1 for the inhalable fraction and vapour can also be checked. Sampling is performed using a flow-regulated pump to draw a defined volume of air through a quartz fibre filter, which is alkaline-impregnated with sodium carbonate and inserted into a GSP sampling system. The volumetric flow rate is 10 l/min. Two hours or 15 minutes are suitable sampling periods. Alternatively, an intake cone suitable for a flow rate of 3.5 l/min can also be used for a sampling period of 2 hours. The methanesulfonic acid deposited on the filter is extracted with 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 0.021 mg/m³. At an LOQ of less than 0.17 mg/m³, the measurement of the STEL is also possible with an air sample volume of 150 litres. The recovery is 100% and the expanded uncertainty is 22% for a 2-hour sampling period and 35% for a 15-minute sampling period.

Please download the article "MAK Commission: Methanesulfonic acid - Determination of methanesulfonic acid in workplace air using ion chromatography (IC)" (in German only).