Alternative Method for the Analysis of Water-Based Metalworking Fluids Using Fourier Transform Infra-Red Spectroscopy

Abstract

Mists of water-based metalworking fluids (MWFs) as a kind of lubricants mineral oil are reported as a respiratory irritant with having carcinogenic compounds such as formaldehyde. Due to the widespread exposure of Iranian metal machining workers to water-based MWFs and limitations of advanced analytical balance in Iran, which is required by the National Institute of Occupational Safety and Health (NIOSH) conventional method No5524, the purpose of this study was set to develop a new analytical method using Fourier-transform infrared (FTIR) spectrometry instead. In this study, the spiked standards in the range of 0.96 to 960 µg/sample were dried and extracted with carbon tetrachloride and scanned by FTIR in the range of 2700 to 3200cm-1 for the best absorption. FTIR and Gas chromatography analysis of formaldehyde as a toxic ingredient of MWFs was examined and its presence was confirmed. For establishing the validation, the merits of the analysis of the FTIR and NIOSH method No.5524, such as precision, accuracy, LOD, LOQ, and bias were obtained that were 1.49%, 103%, 0.0004, 0.0014 µg/sample, -3%, and 10.87%, 111%, 14.9, 49.1µg/sample and 11% respectively. Regression coefficients (r2) of the calibration line with the spiked standards (0.96-960µg/sample) were in the range of 0.997 to 0.999. Since the merits of the analysis of the FT-IR method for water-based MWFs were comparable to the respective NIOSH method, the developed method could be very useful in monitoring lathe workers, especially in developing countries. However, collaborative examination for full validation of the method is recommended