New "on-line" sample-pretreatment procedure for routine liquid-chromatographic assay of low-concentration compounds in body fluids, illustrated by triamcinolone assay.

In this fully automated technique for sample cleanup before chromatographic or other quantitation steps, analytes in body fluids are enriched and semi-purified on a first column. After their selective elution, analytes are "transformed" by admixing appropriate solvents in such a way that they are focused on the top of a second column. By backflush, they then are transferred to an analytical liquid-chromatographic column (or simply eluted for quantification by other techniques). This technique is illustrated by the liquid-chromatographic assay of triamcinolone from a 1-mL urine sample, with ultraviolet detection. Because analytical recovery is almost complete and precision high, no internal standardization is necessary. Interference is eliminated as well as or better than with manual techniques. Chief advantages of this technique are online operation, processing of samples of larger volume, low cost with respect to extraction devices, and nearly universal applicability for exogenous or endogenous compounds of clinical relevance. It potentially may be widely applied.

Spectrophotometric methods for monitoring the microbial transformation of steroids. I. Determination of 9-alpha-fluorohydrocortisone and 9-alpha-fluoro-16-alpha-hydroxyhydrocortisone in fermentation broths.

A method has been devised for the determination of 9alpha-fluorohydrocortisone and 9alpha-fluoro-16alpha-hydroxyhydrocortisone in fermentation broths. The method involves extraction of the two steroids from the broth with ethyl acetate, separation through the formation of the water-soluble borate complex of the vicinally hydroxylated steroid, and estimation of each steroid spectrophotometrically.