The Comparison of Fourier Transform Infrared and Ultraviolet Spectroscopy Techniques for Determination of Mineral Oils

Mineral oils are petroleum derivatives used in metalworking processes. In recent years, considering the carcinogenicity of less refined mineral oil, two separate threshold limit values considered in recent years. The present study designed to compare the spectrometry methods of Fourier Transform Infrared (FT-IR) and ultraviolet (UV), for analysis of mineral oil.
Mineral oils in two different refinement classes were prepared from metalworking processes. Then after determination of density, two types of mineral oils were spiked into Cellulose Ester filter at the same concentration (concentration range: 10-2250µg/sample). Carbon tetrachloride and cold pentane as extraction solvent was used for FT-IR and UV, respectively. Validation parameters including precision, accuracy, detection and quantitation limit were evaluated in both methods.
Detectable concentration ranges of FT-IR and UV methods were close to each other. Intra-day and inter-day coefficients of variation in highly refined oil in FT-IR and UV methods was 5.04, 3.57 and 6.16, 6.01 percent, respectively, and for poorly refined oils in 5.12, 5.21 and 6.36, 6.13 percent respectively. The recovery rates of the two methods was not significantly different (P= 0.461). LOD and LOQ for highly and poorly refined mineral oils in FT-IR and UV analytical methods were 2.61, 2.22 and 7.83, 7.74, and 8.2, 7.3 and 25.84, 15.55 µg/sample, respectively.
FT-IR compared to UV method, has higher precision for analysis of the mineral oils. According validating parameters of this study, FT-IR and UV methods can be used as an alternative to NIOSH methods in the measurement of mineral oils.