Steroid hormones play a crucial role in human physiological functions, and the simultaneous quantification of multiple steroid hormones in biological matrices has considerable clinical relevance. However, the simultaneous quantification of steroid hormones in biological matrices remains analytically challenging due to their ultra-trace concentrations and substantial matrix interference. A novel complementary multi-aptamer strategy was proposed in our study. Multi-aptamer magnetic beads (MA-MBs) were synthesized by simultaneously immobilizing estrogen-specific aptamer (AptE) and corticoid-specific aptamer (AptC) on the magnetic beads. Then MA-MBs was used to extract multiple steroid hormones in biological matrices based on the combined specificity of complementary aptamers. Following extraction, the enriched steroid hormones are quantified using quadrupole time-of-flight liquid chromatography-mass spectrometry (Q-TOF LC-MS). MA-MBs demonstrated a rapid magnetic response (5 seconds), high extraction efficiency, and excellent reusability (at least 10 cycles). Under optimal extraction conditions, the proposed MA-MBs-Q-TOF LC-MS method exhibited a wide linear range (0.02-200 ng/mL), low limits of detection (0.02-1 ng/mL), and high recovery rates (92.93%-104.93%) for 10 types of steroid hormones. Finally, the validated method was applied to quantify ten clinically-relevant steroid hormones in serum samples, demonstrating its potential for advanced endocrine research applications. Furthermore, this study provides a robust platform for multiplexed targets analysis in complex biological matrices.
Furosemide is a widely used loop diuretic in the treatment of congestive heart failure and edema. During the preparation of furosemide, a new process-related impurity G in the levels ranging from 0.08% to 0.13% was detected in pilot batches by a new high performance liquid chromatography (HPLC) method. The new impurity was isolated and characterized by comprehensive analysis of FT-IR, Q-TOF/LC-MS, 1D-NMR (1H,13C, and DEPT), and 2D-NMR (1H-1H-COSY, HSQC, and HMBC) spectroscopy data. The possible formation pathway of impurity G was also discussed in detail. Moreover, a novel HPLC method was developed and validated for the determination of impurity G and the other six known impurities registered in the European Pharmacopoeia as per ICH guidelines. The HPLC method was validated with respect to system suitability, linearity, the limit of quantitation, the limit of detection, precision, accuracy, and robustness. The characterization of impurity G and the validation of its quantitative HPLC method were reported for the first time in this paper. Finally, the toxicological properties of impurity G were predicted by the in silico webserver ProTox-II.Keywords:furosemide;process-related impurity;characterization;Q-TOF/LC–MS and NMR;method validation
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