Chemical fingerprinting of embryotoxic mineral oil

Introduction: Mineral oil is widely used to culture embryos in biomedicine, agriculture, and embryo/stem cell research, yet is poorly defined with significant batch variation causing detrimental effects. The highly hydrophobic nature of this petroleum product attracts polycyclic aromatic hydrocarbons (PAH) and other potentially harmful compounds. Industry requirements for screening oil utilize methods that lack the sensitivity necessary to avoid oil that is overtly embryotoxic or covertly affects embryo development or stem cell derivation. The objective of these experiments was to determine the chemical fingerprints of embryotoxic mineral oil using advanced analytical methods. GC×GC TOFMS is an emerging analytical technique for determining a wide range of environmental contaminants from a single sample. This separation and analysis technique is able to detect sub-pg/l concentrations of ecotoxic contaminants such as PCBs and PAHs.

Materials and methods: Mineral oil with known embryotoxicity identified with time-lapse imaging of mouse embryos was studied. A GC×GC-TOFMS installed with a Rtx-PCB (60 m×0.18 mm×0.18 μm) in the first dimension and Rxi- 17 (1.5 m×0.1 mm×0.1 μm) column in the second dimension was used to separate unknowns. Principal component analysis of data was performed to differentiate the two samples.

Results and discussion: Thousands of unique compounds were identified and quantified in each sample from many classes of chemicals including known environmental toxins. Fingerprinting showed clear differences in the signature of the two oils. Further studies are underway to determine embryotoxicity of individual contaminants as well as development of methods for routine screening of mineral oil quality.