Determination of N-Methyl-2-pyrrolidone in Laboratory Air During Coating of Lithium Ion Battery Electrodes Using Thermal Desorption – Gas Chromatography Mass Spectrometry

N-Methyl-2-pyrrolidone (NMP) is a standard processing solvent for lithium ion battery electrode dispersions. Since NMP is toxic for reproduction, its concentration in laboratory air should be monitored. The time resolved observation of the contamination level exhibits sub-processes, that pose higher or lower risks for an exceedance of the limit values. A method based on thermal desorption coupled to gas chromatography – mass spectrometry (TD-GC-MS) was developed for the quantification of NMP in concentrations close to the derived no-effect level (DNEL). Thermal desorption uses tubes filled with a sorbent material. Air samples are drawn through the tubes. While air passes the sorbent material, contaminations are retained on the material. For analysis, the samples are thermally desorbed and detected by GC-MS. Method parameters like desorption temperature, desorption flow and desorption duration as well as breakthrough were evaluated. The method was applied for the quantification of NMP during a coating process of lithium ion battery electrodes. Determined values for the contamination of laboratory air with NMP in this case study were found to be below DNEL. TD GC MS is a fast and easy to apply method for the quantification of volatile organic compounds like NMP. It offers high desorption efficiency, quick sampling and no need for any solvents, except for calibration purposes.