Response of steroids to sulfuric acid in thin-layer chromatography

Determination of cortisol in plasma and urine by thin-layer chromatography and fluorescence derivatization with isonicotinic acid hydrazide

“…Limitations of the sulphuric acid method do, however, make quantitative analyses of steroids difficult because: 1. The fluorescence strongly depends on the combination of heating time and heating temperature [11][12][13], the use of a precise, temperature-controlled hot-plate is a prerequisite for quantitative analysis. 2.…”

Metabolism of dehydroepiandrosterone by rodent brain cell lines: Relationship between 7-hydroxylation and aromatization

“…A different solvent mixture: xylene-ethyl acetate-chloroform (40:40:20) was used to separate 7␣-OHDHEA (R F : 0.08) from 7␤-OHDHEA (R F : 1.1). Non-radioactive steroids of known identity were added to lanes on the TLC sheets adjacent to the putative metabolites and were visualized and identified by their chromogenic properties after spraying with 5% (v/v) sulphuric acid in methanol and heating on a hot plate [16]. Areas (ca.…”

A colorimetric determination for glycosidic and bile salt-based detergents: applications in membrane protein research

“…In this case, color development was not dependent on the presence of phenol because it directly involved the reaction of the sulfuric acid with the hydroxyl group of the cholate ring [9]. The resulting visible absorption spectra arising from the reaction of 50 ll of 0.4 mM Note.…”

“…The p-semiquinonoid chromogen formed is quantified by absorbance in the visible region (490 nm). We have also observed that detergents belonging to the bile salt class (e.g., CHAPS and cholate) can be quantified by the absorbance increase at 389 nm arising from sulfonation of the cholate ring [9]. We describe the basic procedure of this method and its application in comparison with the radiometric 14 C method to the determination of detergent binding to two integral membrane proteins solubilized and purified in dodecylmaltoside.…”