Chemical Deoxygenation Research Articles

Direct homogeneous phosphoroimmunoassay for carbamazepine in serum.

In this "phosphoroimmunoassay," a phosphorescent label is used: erythrosin (tetraiodofluorescein). Its long-lived phosphorescence was detected after pulsed excitation in a time-resolved luminescence spectrometer. To achieve convenient open-atmosphere phosphorimetry in liquid solution at room temperature, we used sodium sulfite as an "in situ" chemical deoxygenator, to eliminate oxygen quenching of the excited triplet state. Time-resolved detection allows for complete rejection of short-lived background signals, including those from fluorescent or light-scattering components of biological fluids that can interfere in fluoroimmunoassays. We chose the antiepileptic drug carbamazepine (CBZ) and its active metabolite CBZ-10, 11-epoxide (CBZE) to demonstrate the development and validation of nonseparation assays based on quenching the phosphorescence of erythrosin-labeled drug upon binding to antibody. These two compounds cross reacted equally with the antiserum used; hence, we measured the activity of both in patients' sera. Alternatively, simple pre-treatment of the sample with acid destroys CBZE immunoreactivity and enables specific assay of CBZ.

Chemical deoxygenation of the epoxide moiety in deoxynivalenol (vomitoxin)

Reaction of triacetoxydeoxynivalenol (3) with hydrobromic acid–acetic acid at reflux temperatures yielded 3α,7α, 13,15-tetraacetoxy-2-bromo apotrichothec-9-en-8-one (5) and 3α,7α,15-triacetoxy-13-bromo-12-hydroxytrichothec-9-en-8-one (4). Dehalohydrination of the 13,12-bromohydrin derivative with Zn–acetic acid followed by deacetylation with sodium ethoxide gave 3α,7α,15-trihydroxytrichothec-9,12-dien-8-one (2). This compound proved identical to the transformation product isolated from incubation of deoxynivalenol (vomitoxin) in vitro with rumen microorganisms.