Cytokinins: Progress and Developments in Analytical Methods

Since the discovery in the 1950s, cytokinins have been considered to play various important roles in life science. Many analytical procedures, therefore, have been developed for determination of the types, levels and metabolic profiling of endogenous cytokinins. The primary focus of this comprehensive review is on the various analytical methods designed to meet the requirements for cytokinin analyses in complex matrices with special emphasis on gas chromatography (GC), liquid chromatography (LC) and capillary electrophoresis (CE), mostly combined with mass spectrometry (MS). The advantages and drawbacks of the described analytical methods are discussed. As plant tissue contains cytokinins in trace amounts (usually at levels below 30 pmol per gram of fresh weight), the sample pre-treatment steps (extraction, preconcentration and purification) for cytokinins are also reviewed. Finally, the present status and future trends of the analytical approaches are outlined.