Quantitative determination of glycosylated and aglycon isoprenoid cytokinins at sub-picomolar levels by microcolumn liquid chromatography combined with electrospray tandem mass spectrometry

Microcolumn liquid chromatography (mu LC) combined with electrospray tandem mass spectrometry is used for the determination of intact glycosylated cyt okinins and the corresponding aglycons at picomole and sub-picomole levels in plant tissue. Routine analysis was done on C-8-bonded silica using a met hanol-water gradient. Data acquisition was performed by multiple reaction m onitoring, Quantification was carried out by using isotopically labelled an alogues and applying linear regression to the response factor versus concen tration data. For routine analysis a calibration range from 0.5 to 10 pmole injected on-column was used. The limits of detection ranged from 50 to 100 fmole injected on-column. The mu LC procedure was used to analyse plant ti ssue extracts from transgenic homozygote and hemizygote as well as wild-typ e Nicotiana tabacum species, and cauliflower samples. The data were compare d with results obtained by conventional immunoassay and a satisfactory corr elation was found. Validation data are presented. (C) 2001 Elsevier Science B.V. All rights reserved.