The liquid chromatography-tandem mass spectrometry (LC-MS/MS) is an increasingly common tool in the clinical laboratory. Established applications include routine assays for detecting inborn errors of metabolism and for monitoring therapeutic drugs and steroids. Steroid profiling is a very effective method for distinguishing almost all steroid related disorders. It allows accurate diagnosis and ...

Our objective was to identify commercially available digoxin immunoassays whose cross-reactivity with digoxin metabolites paralleled the pharmacological activity of the metabolites. We measured the immunoreactivity of digoxigenin bis- and monodigitoxosides, digoxigenin, and dihydrodigoxin in four immunoassays and compared the immunoactivities with pharmacological activities from studies involvi...

BACKGROUND Determination of the urinary corticoid-to-creatinine ratio (UCCR) is an important screening test in the diagnosis of hypercortisolism (HC). However, urinary cortisol metabolites interfere with cortisol measurement in immunoassays, leading to decreased specificity. Gas chromatography-mass spectrometry (GC-MS) is considered the gold standard for steroid hormone analysis, because it pro...

Immunoassays are among the most powerful and useful techniques for analysis of biological materials. There are numerous variations in which immunoassays can be performed. Coupled with enzyme, using chromogenic substrates, the enzyme immunoassay technique is used to trace the target antigen in tissues. The technique also is used to measure the concentration of antigen in tissue extracts. This ch...

Because current homogeneous immunoassays show some limitations, particularly low sensitivity, we developed a new immunoassay to overcome these limitations. The approach was based on magnetic nanoparticles with a thermoresponsive polymer layer, a negatively charged polymer, and streptavidin-biotin-based antibody-antigen detection and yielded higher sensitivity than commonly used heterogeneous im...

Immunoassays have been widely used as the standard technology for quantitative detection of analyte concentrations in the fields of medicine, environmental science, and food science. Immunoassays such as enzyme-linked immunosorbent assays (ELISA), fluorescence immunoassays (FIA), electrochemical immunoassay (EIA), immunoagglutination assays (IAA) and radioimmunoassays (RIA) are the most commonl...

Drug testing, commonly used in health care, workplace, and criminal settings, has become widespread during the past decade. Urine drug screens have been the most common method for analysis because of ease of sampling. The simplicity of use and access to rapid results have increased demand for and use of immunoassays; however, these assays are not perfect. Falsepositive results of immunoassays c...

Immunoassays are still gaining importance in the central laboratories of large hospitals (see table 1). This trend means that automated techniques are becoming more desirable for immunoassays and many manufacturers are developing new analytical systems. Therefore, it is valuable to examine the technical and analytical requirements for these devices. Very often new immunoassay systems are introd...

Immunoassays are routinely used in the screening of commodities and foods for fungal toxins (mycotoxins). Demands to increase speed and lower costs have lead to continued improvements in such assays. Because many reported mycotoxins are low molecular weight (below 1 kDa), immunoassays for their detection have generally been constructed in competitive heterogeneous formats. An exception is fluor...