Label-free and de-conjugation-free workflow to simultaneously quantify trace amount of free/conjugated and protein-bound estrogen metabolites in human serum.

Different chemical forms of sex hormones including free/conjugated metabolites as well as their protein/DNA adducts in human serum are a panel of important indicators of health conditions. It is, however, hard to quantify all species simultaneously due to the lack of general extraction, derivatization, and de-conjugation methods. Here we developed a label-free and de-conjugation-free workflow to quantify 11 free/conjugated estrogen metabolites including depurinating DNA and protein adduct forms of 4-hydroxyestradiol (4OHE2) in human serum.

[Studies of complexing action mechanism in indirect determination of cysteine by FAAS with ZnS].

Each state of cysteine and zinc ion in aqueous solution at different pH conditions was calculated by computer, giving out the distribution curve. The mechanism of complexing action in indirectly determining cysteine by flame atomic absorption spectrometry with ZnS, and the influence of solution pH were studied. The state of cysteine and zinc ion in aqueous solution at different pH is different.