Quantitative analysis of oxysterols in zebrafish embryos by HPLC-MS/MS.

Zebrafish is an in vivo model used in toxicology to estimate the effects of xenobiotics and their teratogenic consequences. The knowledge of the oxysterols profile in zebrafish, during early embryonic stages, provides important information on the role and biological function of these molecules. This work reports the development and validation of a LC-MS/MS method for the determination of 7 different oxysterols in zebrafish embryos. Sample was treated with a combination of liquid/liquid extraction (LLE) followed by micro solid phase extraction (μSPE) clean-up in order to remove matrix interference and obtain a suitable enrichment factor of the analytes. The method was validated on 2 different embryos growing stages, 3-4 and 24 h post fertilization (hpf), as slight differences in terms of recovery and matrix effect were shown. The validation results provided good accuracy (bias ≤17%; 20% at LOQ) and repeatability (≤15%; ≤19% at LOQ), with low LOQs in the range 22 and 65 pg on 100 embryos sample, without any analyte derivatization, demonstrating the suitability of this analytical method as a useful tool to understand the correlation between oxysterols profile and developmental abnormalities induced by xenobiotic exposure.