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Due to the very low pH of the electrophoretic buffer the authors used reversed polarity electrodes, so the analysis time was significantly reduced. Cho et al. assessed HLB cartridges containing a copolymer sorbent that has hydrophilic and lipophilic groups and provided high recoveries for 21 endogenous corticosteroids. This is caused by the comparatively higher water solubility of the latter compared to the parent molecules.
Robustness of the method was carried out by deliberately making variation in the flow rate (± 0.1 ml/min.) and changing column oven temperature (± 5°C). For the determination of a methods robustness, many method parameters, such as pH, flow rate, column temperature, column oven temperature and column variation etc. . Robustness of an analytical procedures has been defined by the International Conference on Harmonization (ICH) as a measure of its capacity to remain unaffected by small, but deliberate variations in method parameters . Linearity is the ability of a method to test the relationship between analysts concentration with its response (area). From the analysis recovery of Testosterone Undecanoate was found from 98.87 to 100.02% for three concentration levels which is summarized in the Table 3. According to USP guideline accuracy of assay samples should be within 98.0 to 102.0% .
Liquid–liquid extraction was a conventional sample preparation technique used in these publications. In 2008, Shiraishi et al. reported a sensitive method that quantified testosterone and dihydrotestosterone simultaneously, reducing the limit of quantitation (LOQ) to 2 ng/dL . Previously, total testosterone was measured by a chemiluminescent microparticle immunoassay (CMIA) at our institution. The unbound and albumin-bound fractions together make up approximately 35% of testosterone and represent the bioavailable form . SHBG binds testosterone with very high affinity and albumin binds it with lower affinity.
Additionally, the chromatographic separation time could be further reduced on the UHPLC system. The reference method depicted in Figure 2 originated from a HoSt-certified reference laboratory. These results demonstrated that this method was harmonized across all three instruments (Figure 4). We developed a quantitation method using the PRM approach and assessed the instrument performance. High-resolution mass spectrometry is relatively new to clinical laboratories, and its performance has not been well characterized .
To address this limitation, we developed a total testosterone LC-MS/MS assay on three instruments. High-throughput immunoassays often lack accuracy in lower concentration ranges (below 100 ng/dL), particularly when used for females or children. The circulating levels of total testosterone vary from 1 to 1480 ng/dL. The mass spectrometric principle is applicable to the LC/LC-MS/MS where SIL-ISs cancelled the matrix effect in both types of serum. In principle, an internal standard can cancel the matrix effect of an analyte in LC-MS analysis 38–40.
Chromatographic separation of steroid hormones in urine or serum is critical because several of these analytes exhibit the same mass spectrometric MRM transitions (Table 1). Accuracy of the method was determined as the recoveries of analytes spiked at three different concentrations (10, 20 and 200 ng/mL) in both pooled urine and serum. Traditional methods of analysis of steroid hormones in human specimens (such as serum) are radioimmunoassays (RIAs) and enzyme-linked immunosorbent assays (ELISAs). From an electrophoretic viewpoint it has been confirmed that the extraction procedure is most effective for the isolation of analytes and removal of contaminant substances from urine samples. The most common methods used for the quantification of steroid hormones in urine samples are immunological methods 7,8, high-performance liquid chromatography (HPLC) 6,9 or gas chromatography techniques (GC) . The data obtained during this work can be successfully used for further research on the determination of steroid hormones in urine samples.
After holding at 95% B for 0.5 min, the column was equilibrated with 40% B for 2.4 min at a flow rate of 0.6 mL/min. Liquid chromatography and mass spectroscopy conditions were optimized on an API 4500 (SCIEX, Framingham, MA, USA) and a Triple Quad 6500 (SCIEX) triple quadrupole instruments. The quality controls were prepared along with unknowns on each batch to ensure that sample preparation and instrument performance worked as expected. Support liquid extraction cartridge, Isolute SLE+ 400 µL, was procured from Biotage (Charlotte, NC, USA). Acetonitrile (99.9%), formic acid (99.0%), and water were from Fisher Scientific (Hampton, NH, USA). Testosterone (1.0 mg/mL), epitestosterone (1.0 mg/mL), and 2,3,4-13C3testosterone (100 µg/mL) were purchased from Cerillant (Round Rock, TX, USA).

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