Multidimensional chromatographic/mass spectrometric techniques for the trace determination of steroids.
Research has centred on multidimensional chromatographic techniques
which utilise the high specificity of immunoaffinity chromatography for
extraction of analytes from complex biological matrices. On-line
immunoaffinity chromatography-high performance liquid
chromatography-mass spectrometry (IAC-HPLC-MS) systems (IAC and
HPLC coupled via a loop interface) were developed for the confirmatory
analysis of the corticosteroids dexamethasone and flumethasone with MS
detection. Utilising an atmospheric pressure chemical ionisation (APCI)
LC-MS interface, dexamethasone was confirmed in both spiked and post
administration equine urine samples, with a detection limit of 0.1 ug 1-l.
Detection by quadrupole ion trap mass spectrometry (ITMS) using a
particle beam (PB) interface was performed for dexamethasone and
flumethasone in post administration equine urine samples with high
precision (6.9-7.4 %) with limits of detection in the range 3-4 ug 1-l.
Studies were also conducted in this work into the antibody crossreactivity
and non-specific binding of corticosteroids on a HEMA bound
anti-dexamethasone lAC column.
On-line IAC-HPLC and IAC-HPLC-GC have been developed and
assessed for the determination of testosterone in equine urine. A novel
approach to interfacing lAC with HPLC being achieved using a porous
graphitic carbon (PGC) column.
The IAC-HPLC system developed was used for sample pre-treatment for
combustion isotope ratio mass spectrometry analysis. The IAC-HPLC
and IAC-HPLC-GC systems finally being coupled with mass
spectrometry to enable confirmation of the endogenous steroid at
0.5 ug 1-l and 1 ug 1-l respectively in stripped equine urine.