Abstract
The working group "Air Analyses" of the German Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) developed and verified the presented analytical method. It is used to determine the levels of L-(+)-tartaric acid [87-69-4] and D-(-)-tartaric acid [147-71-7] (occurring as inhalable particles) individually or as a racemic mixture [133-37-9] that occur in the workplace air. The method covers concentrations in the range from one tenth up to twice the current Occupational Exposure Limit Value (OELV) of 2 mg/m(3) (inhalable fraction). The method is also suitable for measuring the short-term exposure limit (STEL; excursion factor 2) for the inhalable fraction. Samples are collected by drawing a defined volume of air through a glass fibre filter, which is inserted in a GSP sampling system, using a flow regulated pump at a volumetric flow rate of 3.5 l/min. Exposure during the shift is measured with a sampling period of 2 hours and the short-term exposure with a period of 15 minutes. Tartaric acid deposited on the glass fibre filter is extracted with the IC eluent and analysed by ion chromatography using conductivity detection. The quantitative determination is based on multiple-point calibrations with external standards. A relative limit of quantification (LOQ) of 0.00043 mg/m(3) is obtained for an air sample volume of 420 litres. As the LOQ for a sample volume of 52,5 litres is 0.0034 mg/m(3), the STEL can also be measured. The recovery is 100-104% and the expanded uncertainty is 19-21% for a 2-hour sampling and 20-21% for a 15-minute sampling.