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S Y Su

Publications and source records attributed to S Y Su.

23 records · Page 2Linked to original sources

High performance liquid chromatographic analysis of six conjugated and unconjugated estrogens in serum.

Six estrogens-estrone, equilin, estradiol, sodium estrone sulphate, sodium equilin sulphate and sodium 17-alpha-dihydroequilin sulphate in dog serum were successfully separated and quantified by a high performance liquid chromatographic method developed in our laboratories. The mobile phase was optimized by studying the effects of an organic modifier (acetonitrile) and an ion pairing reagent (tetrabutylammonium hydroxide). The serum sample work-up procedure was designed to recover both conjugated and unconjugated estrogens. The optimum method involved acetonitrile to precipitate serum proteins/peptides and extract estrogens. Residues were reconstituted in 50% acetonitrile in water for injection. The detection limits for these six estrogens via UV detection ranged from 0.5 to 5 ng on-column with a signal-to-noise ratio (S/N) of 10 for a 20 microL injection and via fluorescence 0.1 ng on-column for 17-beta-estradiol. Validation data are included for all six estrogens.

Acetonitriles↗

Room-temperature luminescence analysis of drugs with application to the Toxi-Lab drug identification system.

A method of analyzing drugs on the Toxi-Lab thin-layer chromatographic system by solid substrate room-temperature luminescence is described. Three pairs of unresolved drugs: quinine/cimetidine, caffeine/chlordiazepoxide, and phenazopyridine/lidocaine, were studied as model compounds. Their luminescence characteristics were obtained and calibration curves were found to be linear over two orders of magnitude. The effect of the nonluminescent component of each pair on the determination of the luminescent component was found to be negligible. Statistical F-tests showed that the observed differences in the slopes and intercepts of the calibration curves were due to random errors. The method was evaluated by determining quinine in urine samples at the ng level.

Caffeine↗