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Three deuterated beta-estradiol compounds (2, 4-d2, 16, 16, 17-d3, 2, 4, 16, 16-d4) were investigated for use as internal standard substances in the determination of beta-estradiol. The mass spectrum of two of the deuterated compounds (2, 4-d2, 2, 4, 16, 16-d4) showed structural changes due to hydrolysis (1 M-HCl/methanol, 80°C, 20 min), which was required for the decomposition of conjugates in the sample pretreatment. On the other hand, the mass spectrum of the 16, 16, 17-deuterated compound was not changed. Therefore, we advise that beta-estradiol-16, 16, 17-d3 should be used as the internal standard. In case where beta-estradiol-2, 4, 16, 16-d4 must be used, it should be spiked after hydrolysis.

Investigation of internal standard substances for the determination of beta-estradiol in environmental samples.