An enzyme immunoassay for plasma betamethasone

An enzyme immunoassay for a metabolite of a new sleep inducer (450191-S), a ring-opened derivative of 1,4-benzodiazepine, in human serum

A competitive enzyme immunoassay was developed for metabolites of 450191-S, a ring-opened derivative of triazolobenzodiazepines, in human serum. Three kinds of labelled antigens, beta-D-galactosidase conjugates, and antisera from three kinds of immunogens, bovine serum albumin conjugates, were tested and the hapten heterologous assay was selected. B/F separation was performed using immobilized second antibody and the enzyme activity was measured using fluorescent substrate. One of the serum metabolites, the carboxyl form, was extracted from acidified serum and measured by the assay. The minimum detectable concentration was 1.5 ng/ml in serum, 15 pg/tube. The intra-assay and inter-assay variances were 5.5% and 7.7% at 6 ng/ml of serum, respectively. Standard curves of other related metabolites were assessed with various combinations of labelled antigens and antibodies.

Quantitative determination of betamethasone and its major metabolite in equine urine by micro-liquid chromatography-mass spectrometry

Micro-liquid chromatography-mass spectrometry (micro-LC-MS) was utilized to quantitatively determine betamethasone and its major unconjugated metabolite, 6 beta-hydroxybetamethasone, in equine plasma and urine. The advantage of micro-LC-MS over conventional gas chromatography-mass spectrometry in corticosteroid determination is illustrated and the reliable, steadfast nature of micro-LC-MS is demonstrated through example.

Qualitative detection of corticosteroids in equine biological fluids and the comparison of relative dexamethasone metabolite/dexamethasone concentration in equine urine by micro-liquid chromatography-mass spectrometry

Several important corticosteroids were qualitatively determined in the plasma and urine of horses by micro-liquid chromatography-mass spectrometry (micro-LC-MS). The sensitivity and specificity of micro-LC-MS are demonstrated as is the ability of micro-LC-MS to deal with endogenous interferences. In turn, the relative amount of dexamethasone and its major unconjugated metabolite were determined in equine urine by micro-LC-MS; the conclusions drawn are reported.

An enzyme immunoassay for serum tobramycin

A heterogeneous enzyme immunoassay for serum tobramycin was developed using tobramycin-beta-D-galactosidase conjugate as the labelled antigen and 4-methylumbelliferyl-beta-D-galactoside as the fluorescence substrate. B/F separation was carried out using an immobilized second antibody, Immunobead. The minimal detectable level was 10 pg/tube or 0.2 microgram/ml of serum. Assay recovery was excellent and the intra-assay and inter-assay variances were 4.41% and 12.6%, respectively. The values from the enzyme immunoassay agreed well with those from radioimmunoassay and bioassay. This assay system is highly sensitive and can be easily applied to other drugs and hormones.