Determination of 17-oxosteroid sulphates in serum by ion-pair extraction, prelabelling with dansylhydrazine and high-performance liquid chromatography with fluorescence detection

Perfluorosulfonated Ionomer-Modified Polyethylene. A Material for Simultaneous Solid-Phase Enrichment and Enhanced Precolumn Dansylation of C-21 Ketosteroids in Human Serum

“…Unfortunately, these conditions are prevailing and the only way of circumventing this problem is to use a larger excess of reagent leading to excessive reagent blanks or to employ a more efficient catalyst. It has been shown that the type of acid used to catalyze the reaction influences both the rate and yield of the hydrazone formation reaction. − In this context, we have introduced and optimized the use of trifluoromethanesulfonic acid (TFMSA) as a catalyst for precolumn dansylation of a number of ketosteroids. Using this catalyst, which is among the strongest known monoprotic Brönsted acids, it is possible to quantitate low-picomole levels of ketosteroids in both plasma and serum. , Unfortunately, this acid spontaneously forms highly toxic and carcinogenic methyl triflate when diluted in anhydrous methanol, a required component of the derivatization reagent.…”

“…It has been shown that the type of acid used to catalyze the reaction influences both the rate and yield of the hydrazone formation reaction. [7][8][9][10] In this context, we have introduced 11 and optimized 12 the use of trifluoromethanesulfonic acid (TFMSA) as a catalyst for precolumn dansylation of a number of ketosteroids. Using this catalyst, which is among the strongest known monoprotic Bro ¨nsted acids, it is possible to quantitate low-picomole levels of ketosteroids in both plasma and serum.…”