Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

3 posts Page 1 of 1
Helo everyone
I'm upon developing new method for analyzing dydrogesterone using Ms/Ms with ESI
anyone can help me with a proper start ?
To be honest, your first step should probably be to see if you've got an APCI probe instead of ESI; it's going to give you much better sensitivity...
This can be done by ESI +ve , see below

by JMB » Wed Apr 18, 2018 10:29 pm
The original ref. for very low concn of acids for steroids is,

Journal of Chromatography A
Volume 964, Issues 1–2, 26 July 2002, Pages 137-151

Analysis of ergosteroids: VIII: Enhancement of signal response of neutral steroidal compounds in liquid chromatographic–electrospray ionization mass spectrometric analysis by mobile phase additives

Ashok Marwah, Padma Marwah, Henry Lardy

The signal response of moderately polar to nonpolar neutral steroidal compounds in positive ion mode was significantly improved in electrospray ionization mode by addition of volatile organic acids (trifluoroacetic acid, acetic and formic) at concentrations much lower than those normally employed for high-performance liquid chromatographic separations of ionic compounds. Each of the three acids enhanced the sensitivity, the order being: formic acid (∼50–200 ppm, v/v)>acetic acid (100–500 ppm)>trifluoroacetic acid (5–20 ppm). Higher concentrations caused decrease in the sensitivity. The extent of increase in the sensitivity was compound specific and also depended on the nature of organic modifier present in the mobile phase. Acetic acid was the acid of choice for the ‘wrong-way-round’ ionization of sulfate conjugates. The postcolumn addition of silver nitrate produced highly stable (M+Ag)+ adducts with concomitant increase in signal response and reduction in baseline noise.

3 posts Page 1 of 1

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