Washing mineral oil reduces contaminants and embryotoxicity

Objective: To determine if washing improves the quality of mineral oil used for embryo culture. Design: A 2 x 3 factorial experimental study. Setting: University hospital-based infertility center. Animal(s): Mice. Intervention(s): The chemical nature of contaminants present in two lots of mineral oil was determined. Effect of washing on toxicity and amount of toxin present in media was determined. Main Outcome Measure(s): The effect of washing was determined by a quality control bioassay or by directly determining the level of contaminant in oil-conditioned culture media. Result(s): Water, culture media, and media plus albumin were equally effective in reducing toxicity and concentration of toxin. Temperature did not affect washing results. Peroxide, aldehydes, and alkenals were present in one lot of oil, and Triton X-100 was identified in the other lot. Washed oil containing peroxide passed the one-cell mouse embryo bioassay, and washing reduced the amount of Triton X-100 by 25%. Conclusion(s): Mineral oil is the least defined component used for in vitro fertilization and embryo culture; therefore, it is important to determine if washing oil is beneficial. This study provides clear evidence that washing reduces toxicity of mineral oil. (Fertil Steril (R) 2010;94:2747-52. (C) 2010 by American Society for Reproductive Medicine.)