| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4529301 | Aquatic Toxicology | 2014 | 7 Pages |
•Internal concentrations of polar compounds are overestimated in unhatched zebrafish embryos.•Dechorionation before sample preparation is proposed for the quantification of true internal concentrations.•Short time exposure experiments provide a reasonable estimate of the substance concentration in the perivitelline space.•For the polar substances tested, the chorion of the zebrafish embryo does not represent a transport barrier.
The chorion and the perivitelline space which surround unhatched zebrafish embryos (ZFE, Danio rerio) may affect the determination of internal concentrations of study compounds taken up in early life-stages of ZFE. Internal concentration-time profiles were gathered for benzocaine, caffeine, clofibric acid, metribuzin and phenacetin as study compounds over 96 h of exposure starting with ZFE at 4 h post-fertilization. Liquid chromatography coupled to tandem-mass spectrometry (LC–MS/MS) was used to determine the concentration of the study compounds from intact (i.e. unhatched), dechorionated and from hatched ZFE. The mass of the study compounds per ZFE was 5–30 ng higher for intact ZFE compared to dechorionated ones. Thus, internal concentrations were overestimated if only intact ZFE were analyzed. Dechorionation of unhatched ZFE after their exposure is proposed to determine the true internal concentration in the embryo. For the compounds studied here the mass of the study compounds determined in unhatched ZFE after a short term (5 min) exposure provided a reasonable estimate of the mass taken up by the chorion and the PVS. This mass can be subtracted from the total mass found in unhatched ZFE to calculate the true internal mass. Estimating the mass in the chorion and the PVS from the concentration of the study compound in the external exposure medium and the volume of the PVS provided no reasonable results.
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