“…Other methods use HPLC-mass spectrometry [10][11][12] which has the disadvantage of being expensive and not available in all laboratories. Some of these methods use fluorimetric derivatisation before HPLC analysis [5,13] which is limited by the precisely controlled reaction conditions and the instability of the fluorescent analogue [9]. Many of these methods give rise to long retention times for prednisolone and cortisol of up to 20 min [4,14,15].…”