Novel luminescent compounds for immunoassay

The thesis describes the synthesis of ruthenium bipyridyl and phenanthro1ine compounds that are luminescent. Several of the compounds were suitably derivatised for protein conjugation i.e. [Please see inside of thesis for formulas] The excitation and emission spectra were recorded for the above compounds and their luminescent lifetimes determined. Some of the above compounds were conjugated to antibody samples and their luminescent characteristics recorded. It was found that the complex-antibody conjugates had similar properties to their parent complexes possessing a large Stoke's Shift (about 130-140 nm) and a long luminescent lifetime (125-1200 ns). Hence these compounds may be of use as protein labels in time resolved immunoassays. The thesis also describes the synthesis of some luminescent chromium and aluminium compounds i.e. [Please see inside of thesis for formulas] Their luminescent characteristics were investigated. The preparation of several oxine derivatives was also attempted with varying success. The thesis ends with an epilogue discussing science as a God-given activity

Dynamics of serum testosterone during the menstrual cycle evaluated by daily measurements with an ID-LC-MS/MS method and a 2nd generation automated immunoassay

Background: Testosterone concentrations in normally cycling women are assumed to be elevated around the time of ovulation. The clinical relevance of changing testosterone concentrations during the menstrual cycle, however, is unclear. Poor performance of current direct immunoassays for testosterone at low concentrations confounds this issue. Therefore, our objective was to assess daily testosterone fluctuation during the menstrual cycle by a thoroughly validated isotope dilution-liquid chromatography-Tandem mass spectrometry (ID-LC-MS/MS) method and to evaluate whether an ARCHITECT® 2nd Generation Testosterone fully automated immunoassay is equally suited for this purpose. Methods: Testosterone was measured in serum obtained daily during the menstrual cycle of 25 healthy women, characterized by biochemical and physical examination. Results: Performance of the ID-LC-MS/MS method was concordant with a published reference method (y = 1.007x - 0.056 nmol/L; r = 0.9998). Comparison of the immunoassay to ID-LC-MS/MS yielded y = 1.095x + 0.104 nmol/L (r = 0.9031). Overall, testosterone concentrations were higher mid-cycle, but a peak was not discernible in each individual. Apart from a persistent positive bias, the immunoassay measured the same testosterone profiles as the ID-LC-MS/MS method. The reference interval in women was 0.30-1.69 nmol/L (8.7-48.7 ng/dL) for ID-LC-MS/MS and 0.50-2.00 nmol/L (14.4-57.7 ng/dL) for the immunoassay. Conclusion: The elevation of mid-cycle testosterone concentrations is statistically significant, although not clinically relevant since day-To-day variation is higher and independent of the menstrual cycle. In this light, a single testosterone measurement might not be reflective of the overall testosterone status in an individual. Measurements obtained using the 2nd generation immunoassay gave comparable results across the menstrual cycle. © 2012 Elsevier Inc. All rights reserved

Testosterone, free testosterone, and free androgen index in women: Reference intervals, biological variation, and diagnostic value in polycystic ovary syndrome

Objective: The objective of our study was to determine reference intervals and biologic variation for testosterone (T), free testosterone (fT), and free androgen index (FAI) in women with accurate methods and to test the discriminative value of these parameters in a polycystic ovary syndrome (PCOS)-population. Methods: Serumwas obtained daily during a normal menstrual cycle from 25 healthy women (677 data-points). A single serum sample was obtained from 44 PCOS-patients. T was measured by LC-MS/MS and by Architect® 2nd generation T Immunoassay. Sex hormone-binding globulin was measured to calculate fT and FAI. Results: Reference intervals which were established in healthy women with an ovulatory menstrual cycle were T = 0.3-1.6 nmol/L and 0.5-2.0 nmol/L, fT = 5.2-26 pmol/L and 7.2-33 pmol/L, and FAI = 0.4-2.9 and 0.6-4.4, by LC-MS/MSand immunoassay, respectively. T, fT and FAIwere higher in PCOS patients than in controls (p b 0.0001). The areas under the curve of receiver operator characteristic (ROC) plots were not different for T, fT, or FAIwhen Twasmeasured by LC-MS/MSversus immunoassay based on prediction of PCOS. FAI and fTwere the strongest predictors of PCOS. Conclusions: When based upon the appropriate reference intervals and ROC analysis, LC-MS/MS and second generation immunoassay have equivalent clinical utility for the diagnosis of PCOS

State-of-the-art of serum testosterone measurement by isotope dilution-liquid chromatography-tandem mass spectrometry

BACKGROUND: The recent interest of clinical laboratories in developing serum testosterone assays based on isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) stems from the lack of accuracy of direct immunoassays. In this study, we assessed the accuracy and state of standardization (traceability) of 4 published ID-LC-MS/MS procedures in a method comparison with an ID-gas chromatography (GC)-MS reference measurement procedure listed in the database of the Joint Committee for Traceability in Laboratory Medicine. METHODs: The study used 58 specimens from different patient categories. Each specimen was measured in triplicate (ID-LC-MS/MS) and quadruplicate (ID-GCMS) in independent runs. RESULTS: The testosterone concentrations by ID-GC-MS were 0.2-4.4 nmol/L (women), 0.2-2.0 nmol/L (hypogonadal man), and 10.1-31.3 nmoVL (normogonadal men). For ID-GC-MS, the CV was nearly constant, with a median of 1.0%; for ID-LC-MS/MS, it was concentration-dependent, with a median of up to 8%. Weighted Deming regression gave mean slopes, intercepts, and correlation coefficients of 0.90-1.11, -0.055-0.013 nmol/L, and 0.993-0.997, respectively. The % difference plot showed between 7% and 26% of the results outside a total error limit of 14%, with median deviations from ID-GC-MS between -9.6 and 0.4%. CONCLUSIONS: This study demonstrated fairly good accuracy and standardization of the tested ID-LCMS/MS procedures. Performance differences between procedures were evident in some instances, due to improper calibration and between-run calibration control. This emphasizes the need for thorough validation, including traceability, of new ID-LC-MS/MS procedures