Durand Alegría, Jesús SenénPérez Conde, ConcepciónFernández Hernando, PilarPaniagua González, Gema2024-05-202024-05-202003-02-281618-2642 - eISSN 1618-2650https://doi.org/10.1007/s00216-002-1746-4https://hdl.handle.net/20.500.14468/11610Digoxin is a very important compound in clinical chemistry and is indicated in the treatment of congestive heart failure and artery disease. The measurement of serum digoxin concentration is necessary owing to the narrow therapeutic range of this drug. Further, even with similar dosage regimens, the biological response of patients often results in very different concentrations of digoxin in serum. Concentrations of greater than 2.6 mmol/L are generally interpreted as toxic in adult patients. Most methods for digoxin determination are based on gas chromatography or radiochemical and enzymatic immunoassay techniques. However, some of these methods are tedious and difficult to automate. Nowadays, they are being replaced by more practical immunoassay techniques, involving, for example, fluorescent immunosensors that allow rapid, automated and selective digoxin determinations. This paper reports a new flow–through fluoroimmunosensor for digoxin determination, the function of which is based on antibodies immobilized on an inmunoreactor of controlled pore glass (CPG). The immunosensor has a detection limit of 1.20 μg/L and provides high reproducibility (RSD = 4.5% for a concentration of 0.0025 mg/L, and RSD = 6.7% for 0.01 mg/L). The optimum working concentration range was found to be 1.2×10-3 - 4.0×10-2 mg/L. The lifetime of the immunosensor was about 50 immunoassays, if stored unused its lifetime can be extended to three months. A sample speed of about 10–12 samples per hour can be attained. Possible interference from substances with structures similar to digoxin (morphine, heroine, tebaine, codeine, pentazocine and narcotine) was investigated. No cross-reactivity was seen at the highest digoxin:interferent ratio studied (1:100). The proposed fluoroimmunosensor was successfully used to determine digoxin concentrations in human serum samples.enAtribución-NoComercial-SinDerivadas 4.0 Internacionalinfo:eu-repo/semantics/openAccessartículoflow-through fluoroimmunosensordigoxinpermanent immobilizationserum samples