D2O assisted FTIR spectroscopic analysis of moisture in edible oil

Abstract

D2O-assisted moisture analysis of edible oils was investigated. The acetonitrile extract of the oil samples was split into two parts. The spectrum of one part was taken as is, another was recorded after addition of excess D2O. Changes in spectral absorption of the HOH bending band (1600–1660 cm−1) was used to calculate moisture in oil samples. To effectively depleting absorption of water in the acetonitrile extract, a 30-fold excess of D2O is required. The typical OH-containing constituents in oil did not show significant interference on the H/D exchange. Validation experiments by using five oils with five levels of moisture spiked (50–1000 μg/g) suggested that the prediction tracked the spiked amounts well. The results of variance analysis indicate that there is no difference in terms of analytical methods and oil types used (p < 0.001). The D2O method developed is generally applicable to the accurate analysis of moisture at trace levels (<100 μg/g) in edible oils.

Keywords

• Water content
• Fourier transform infrared spectroscopy
• Edible oil
• Deuterium oxide
• Acetonitrile extraction