# Stickstoffdioxid – Bestimmung von Stickstoffdioxid in der Luft am Arbeitsplatz mittels Ionenchromatographie (IC): Luftanalysen-Methode

## TL;DR

This paper presents a method to measure nitrogen dioxide levels in workplace air using ion chromatography for accurate and reliable detection.

## Contribution

A validated analytical method for measuring nitrogen dioxide in workplace air using ion chromatography with triethanolamine.

## Key findings

- The method can detect nitrogen dioxide concentrations from one tenth to twice the occupational exposure limit.
- The mean recovery is 108% with an expanded uncertainty below 28% for a 2-hour sampling period.
- The relative limit of quantification is 0.009 mg/m³ for a 216-liter air sample.

## 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 nitrogen dioxide [10102-44-2] 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 0.95 mg/m3 (0.5 ml/m3). Samples are collected by drawing a defined volume of air through a sampling tube filled with aluminium oxide carrier material coated with triethanolamine (TEA) using a flow regulated pump at a volumetric flow rate of 1.8 l/min. The exposure during the shift is assessed with a sampling period of 2 hours and the short-term exposure with a period of 15 minutes. Nitrogen dioxide reacts with TEA with formation of TEA nitrite and TEA nitrate. Nitrite and nitrate are extracted with ultra-pure water 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 0.009 mg/m3 is obtained for an air sample volume of 216 litres. As the LOQ for a sample volume of 27 litres is well below 0.95 mg/m3, the short-term exposure limit (STEL; excursion factor 2) can also be measured. The mean recovery is 108% and the expanded uncertainty is below 28% for a sampling period of 2 hours.