Determining estrogens using surface-assisted laser desorption/ionization mass spectrometry with silver nanoparticles as the matrix
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- Chiu, TC., Chang, LC., Chiang, CK. et al. J Am Soc Mass Spectrom (2008) 19: 1343. doi:10.1016/j.jasms.2008.06.006
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We describe the application of silver nanoparticles (Ag NPs) as matrices for the determination of three estrogens using surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Because Ag NPs have extremely high absorption coefficients (1.2 × 108 M−1 cm−1) at 337 nm, they are effective SALDI matrices when using a nitrogen laser. Three tested estrogens—estrone (E1), estradiol (E2), and estriol (E3)—adsorb weakly onto the surfaces of the Ag NPs, through van der Waals forces. After centrifugation, the concentrated analytes adsorbed on the Ag NPs were subjected directly to SALDI-MS analyses, with the limits of detection for E1, E2, and E3 being 2.23, 0.23, and 2.11 µM, respectively. The shot-to-shot and batch-to-batch variations for the three analytes were less than 9% and 13%, respectively. We validated the practicality of this present approach through the quantitation of E2 in human urine. Using this approach, we determined the concentration of E2 in a sample of a pregnant woman’s urine to be 0.16 ± 0.05 µM (n = 10).