Rapid, fully automated measurement of plasma homocyst(e)ine with the Abbott IMx analyzer.

We have developed a totally automated fluorescence polarization immunoassay for homocyst(e)ine with no pretreatment or chromatographic steps. Comparison with four well-established chromatographic methods yielded r values ranging from 0.980 to 0.997 and slopes from 1.030 to 1.493. Inter- and intraassay CVs ranged from 0.0% to 8.0% and from 0.0% to 6.4%, respectively. Imprecision (CV) of measuring six plasma samples on three instruments ranged from 6.3% to 10.2%. The assay was linear for plasma samples diluted with buffer from 0 to 8-fold. Mean recovery of homocysteine added to two plasma samples was 97.1% and 99.9%. The assay exhibited almost no cross-reactivity towards cysteine and methionine, and a batch of 20 samples can be processed in 60 min.

Hydrophilic fluorescein derivatives: useful reagents for liposome immunolytic assays.

Hydrophilic derivatives of fluorescein containing hydroxyalkyl substituents were synthesized and encapsulated within liposomes. The fluorophores showed significantly more retention with time than did fluorescein, carboxyfluorescein, or calcein. Unlike calcein, the fluorophores are minimally susceptible to fluorescence quenching by Co2+. The utility of these compounds as immunodiagnostic reagents was demonstrated by encapsulating 5(6)-carboxyfluorescein trismethylolamide in haptenized liposomes which were used in an immunoassay for digoxin.

4'-[Aminomethyl]fluorescein and its N-alkyl derivatives: useful reagents in immunodiagnostic techniques.

A new class of fluorescein derivatives with chemically reactive amino and N-alkylamino "arms" in the 4'-position were synthesized and their utility in the development of fluorescence polarization immunoassays (FPIA) for cortisol and estriol was evaluated. The positioning of the arm in one of the phenolic rings introduced chirality due to hindered rotation and led to rotational isomers. These were separable when brought into a chiral environment, i.e., conjugated to steroid molecules. In the case of cortisol conjugates, the rotamers had similar properties in the FPIA. In the case of estriol conjugates, however, each rotamer exhibited different immunoassay characteristics. The rotamers interconverted at 80 degrees C, with the rate increasing with temperature. An unusual N-alkylation phenomenon by alkanols in acidic medium was observed. A serum cortisol FPIA, developed using an N-alkylamino fluorescein derivative, showed good correlation with a reference RIA.

A revised structure of fluorescein mercuric acetate.

With the help of NMR spectroscopy the structure assignment of fluorescein mercuric acetate is corrected to 4',5'-bis(acetoxymercury)fluorescein.

Allyl derivatives of zearalenone.

The Claisen rearrangement of 4-O-allylzearalenone led to only one principal product, which was identified as 3-allylzearalenone with the aid of photochemical isomerization and PMR spectroscopy. This general method is useful for distinguishing 3-substituted zearalenone isomers from 5-substituted isomers. Hydrogenation of 3-allylzearalenone gave 3-(1-propyl)zearalanone.

Coumarins XIV: high-resolution mass spectra of 3',4'-disubstituted 3',4'-dihydroseselins.

High-resolution mass spectra of 14 3',4'-disubstituted 3',4'-dihydroseselins were examined. The nature of the substituents determinines the mode of fragmentation. Compounds having one or two acyloxy substituents fragment mainly by a pathway leading to the stable coumarinopyrilium ion. Coumarins with alkoxy or hydroxy substituents proceed by way of fission of the chroman ring, accompanied by the loss of two ring carbon atoms. Several generalizations are formulated which will aid in the interpretation of the mass spectra of this class of coumarins from a structural standpoint.