title: Analysis of cytokinin nucleotides in coconut (Cocos nucifera L.) water using capillary zone electrophoresis-tandem mass spectrometry after solid-phase extraction.
abstract: A method based on solid-phase extraction (SPE) and capillary zone electrophoresis-tandem mass spectrometry (CZE-MS/MS) is described for the separation and determination of six cytokinin nucleotides in coconut water. The best CZE separation for the six cytokinin nucleotide standards was achieved using a 25 mM ammonium formate/formic acid buffer (pH 3.8) and 2% (v/v) methanol with an applied gradient separation voltage (25 kV for 32 min, and then a linear gradient to 30 kV in 5 min, finally 30 kV to the end of separation) in less than 60 min. MS/MS with multiple reaction monitoring (MRM) detection was carried out to obtain sufficient selectivity and sensitivity for the cytokinin nucleotides. The combined use of on-line sample stacking and CZE-MS/MS achieved limits of detection (LODs) in the range of 0.06-0.19 microM for the six cytokinin nucleotides at a signal-to-noise ratio of 3. Furthermore, a novel dual-step SPE procedure was developed for the pre-concentration and purification of cytokinin nucleotides using Oasis HLB and Oasis MAX cartridges. The recoveries of the cytokinin nucleotides after the dual-step SPE were in the range of 44-71%. The combination of off-line SPE, on-line sample stacking and CZE-MS/MS approach was successfully applied to screen for endogenous cytokinin nucleotides present in coconut water sample. trans-Zeatin riboside-5'-monophosphate (ZMP) was detected and quantified in coconut water by CZE-MS/MS after SPE and on-line sample stacking.
authors.affiliation: Natural Sciences and Science Education Academic Group, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Singapore.
authors.forename: Liya
authors.initials: L
authors.lastname: Ge
authors.forename: Jean Wan Hong
authors.initials: JW
authors.lastname: Yong
authors.forename: Swee Ngin
authors.initials: SN
authors.lastname: Tan
authors.forename: Xin Hao
authors.initials: XH
authors.lastname: Yang
authors.forename: Eng Shi
authors.initials: ES
authors.lastname: Ong
mesh_terms: D003059:Cocos / Q000737:chemistry*; D003583:Cytokinins / Q000032:analysis* / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000379:methods*; D013058:Mass Spectrometry / Q000379:methods*; D015394:Molecular Structure; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
chemical_list: D003583:Cytokinins