A lower voltage caused the separation time to be longer and the phenomenon of "tailing peaks" appeared. The most optimal separation conditions prevailed when a temperature of 22 °C was employed, therefore all separations were carried out at 22 °C. The temperature has an influence on the density and the mobility of ions, as well as on the volume of the injected sample. On the other hand, too short an injection time can result in a too small amount of the sample injected into the capillary, thereby reducing the peak height or creating the absence of signals.
Few earlier studies employed lengthy chromatographic separation time to isolate and resolve individual analytes 5,19. LOD and LOQ of target analytes in urine were calculated as 3 and 10 times the standard deviation (SD), respectively. The inter-day CV was measured by repeated injection of fortified samples on three different days.
It is a competitive immunoassay using anti-testosterone monoclonal-antibody-coated microparticles and acridinium-labeled testosterone. In children, total testosterone is used to evaluate precocious or delayed puberty. In men, total testosterone measurement is important in hypogonadism workup. Testosterone is a steroid hormone that is crucial in the development of male reproductive tissues and essential for the maintenance of secondary sexual characteristics. This assay was harmonized across two triple quadrupole instruments and one high-resolution mass spectrometer. A supported liquid extraction cartridge was used to extract the analyte from biological matrices.
In addition, the calibration samples of E1 and E3 were prepared by spiking working solutions into blank matrix. The concentrations of IS in this working solution were 1 ng/ml for E1-d4, E2-d2, and E3-d3, 10 ng/ml for T-d3 and P-d9, 20 ng/ml for DHEA-d6, 5 ng/ml for AD-13C3, and 17-OHP-d8. For LC separation, formic acid in water (0.2% v/v) with ammonium acetate (10 mmol/l) and formic acid in methanol (0.2% v/v) with ammonium acetate (10 mmol/l) were used as mobile phase A and B, respectively. For extraction, samples are allowed to stand under subzero temperature after protein precipitation by ACN.
Concentrations of the target analytes were 100 ng/mL; Injection volume was 10 µL. Dansylation of estrone, estradiol, and estriol improved their chromatographic resolution and sensitivities. Aldosterone, 11-deoxycorticosterone, estradiol, and estriol were below the respective LODs in the sample. In particular, the LODs for estrogens in urine in our study (0.04–0.17 ng/mL) were significantly lower than those reported in an earlier study (0.20–0.83 ng/mL) .

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