Determination of retigabine and its acetyl metabolite in biological matrices by on-line solid-phase extraction (column switching) liquid chromatography with tandem mass spectrometry
Ng. Knebel et al., Determination of retigabine and its acetyl metabolite in biological matrices by on-line solid-phase extraction (column switching) liquid chromatography with tandem mass spectrometry, J CHROMAT B, 748(1), 2000, pp. 97-111
A HPLC assay with tandem mass spectrometric detection in the positive-ion a
tmospheric pressure chemical ionisation (APCI) mode for the sensitive deter
mination of retigabine [(I), D-23129] and its acetyl metabolite [(II), ADW
21-360] in plasma was developed, utilising the structural analogue (D-10328
), (III), as internal standard. Automated on-line solid-phase extraction of
diluted plasma samples, based on 200-mul plasma aliquots, at pH 6.5, allow
ed a reliable quantification of retigabine and the acetyl metabolite down t
o 1 ng/ml. Injection of 500 mul of diluted plasma onto a C-2 stationary pha
se-based column switching system in combination with a 75 mmx4 mm reversed-
phase analytical column at a flow-rate of 0.5 ml/min provided cycle times o
f 4 min per sample. The standard curves were linear from 1 to 1000 ng/ml us
ing weighted linear regression analysis (1/x(2)). The method is accurate (m
ean accuracy less than or equal to+/-10%), precise (RSD <+15%) and sensitiv
e, providing lower limits of quantification in plasma of 1 ng/ml for retiga
bine (I), and 2.5 ng/ml for the metabolite (II) with limits of detection of
0.5 ng/ml for both analytes. Up to 200 unknowns may be analysed each 24 h
per analyst. (C) 2000 Elsevier Science B.V. All rights reserved.