Purification protocol for cytokinins using multi-StageTips (STop And Go Extraction Tips). Three different sorbents (C18/SDB-RPS/Cation-SR) were placed in an ordinary pipette tip and inserted into a microcentrifuge tube (1.5 ml). Plant material (1–5 mg) was homogenized and extracted in Bieleski buffer containing labelled internal standards. Pooled supernatant was applied (1 mg FW 50 μl–l) to a pre-conditioned multi-StageTip microcolumn, which was then washed and eluted with the indicated solutions. The eluate was evaporated to dryness, dissolved in 20 μl of 10% methanol and analyzed by UHPLC-MS/MS method.