ポスター発表
- 第1日 5月15日（火） ポスター会場
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1P-47 PDF
Detection of hydrophilic steroids in negative mode by Triple Quadrupole Mass Spectrometry
Steroid hormones are hydrophobic and small molecules, known to have a profound biological impact on target cells or organs. Dehydroepiandrosterone (DHEA) is the biological synthetic source of many predominant steroids, such as Androgens. 7-α-hydroxydehydroepiandrosterone (7α-OH-DHEA) is one of its hydroxylated metabolite. It has been reported that 7α-OH-DHEA was able to counteract immunosuppressive effects of glucocorticoids. 7-α-Hydroxypregnenolone (7α-OH-Preg), which is the hydroxylated product of Pregnenolone, plays an important role in endocrine disease. This kind of hydroxylated steroids also includes 17a-Hydroxypregnenolone (17-OH-Preg). As shown in Figure 1, these hydroxylated steroids are more hydrophilic, compared with others. They are more easily dehydrated in positive-ion mode in electrospray ionization after being protonated, leading to production of diverse ions (Figure 2). As the result, it depresses detecting sensitivity of MH+ ion and makes the quantitative analysis with multiple reaction monitoring (MRM) difficult. To overcome this issue, measurement in negative-ion mode could be a choice for the analysis of hydroxylated steroids.
Herein, we have examined the performance of negative-ion mode in the analysis of hydrophilic steroids with a UPLC–MS/MS. To enhance the ionization efficiency, 0.4 mM NH4F aqueous solution was used for mobile phase. The analytes were detected under MRM mode. The dehydration phenomenon was less obvious under negative-ion mode and the signal over noise (LOD) was much better.