1 © The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com Journal of Chromatographic Science, 2019, 1–11 doi: 10.1093/chromsci/bmz074 Article Article Determination of Major Phytohormones in Fourteen Different Seaweeds Utilizing SPE–LC–MS/MS Sibel Yalçın 1, *, Emine ¸ Sükran Okudan 2 , Özge Karaka¸ s 1 and Ay ¸ se Nur Önem 3 1 Chemistry Department, Faculty of Engineering, Istanbul University Cerrahpa¸ sa, Avcilar, Istanbul 34320, Turkey 2 Marine Biology Department, Faculty of Aquatic Sciences and Fisheries, Akdeniz University, Antalya 07070, Turkey, and 3 Application & Research Center for the Measurement of Food Antioxidants, Istanbul University Cerrahpa¸ sa, Avcılar, Istanbul 34320, Turkey * Author to whom correspondence should be addressed. Email: sibelyal@istanbul.edu.tr Received 3 December 2018; Revised 20 June 2019; Accepted 20 August 2019 Abstract Analysis of plant growth regulators (PGRs) should be approached by considering their extremely low concentrations and serious interfering effects that result from the matrix of various plant tissues. In the current research, the separation and simultaneous determination of different classes of phytohormones in 14 seaweeds collected from Turkey seashores were achieved by using solid- phase extraction (SPE) followed by a rapid and sensitive liquid chromatography tandem mass detection method. OASIS HLB (Hydrophilic-Lipophilic Balance) cartridges were successfully used for SPE process to eliminate the matrix effect and enhance the PGRs including zeatin, benzyl amino purine, indole-3-acetic acid, abscisic acid and gibberellic acid within partially different polarities. Based on the optimized experimental conditions, the method presented excellent performance related to linearity (r , 0.9996–0.9999) within the ranges of 0.5–500 ng/mL, relative standard deviation values ((1.43–2.01) for intraday and (2.36–3.50) for interday)), the limit of detection (0.01–0.84 μg/L) and the limit of quantification (0.02–2.76 μg/L). The obtained results confirm that the SPE–liquid chromatography/tandem mass spectrometry method performed is highly effective and convenient for routine analyses of trace amounts of the tested phytohormones in seaweeds and any other plant samples as well. Introduction A plant growth regulator (PGR), which is often defined as bios- timulator, is either a natural or synthetic organic compound that controls or modifies physiological events in a plant. Phytohormones are divided into two main groups as plant growth stimulants (aux- ins, gibberellins, cytokinins) and bioinhibitors (abscisic acid (ABA)). Growth stimulants are responsible for cell division, enlargement, organ formation, flowering, fruiting and seed formation, whereas bioinhibitors play an essential role in dormancy and germination, leaf and organ senescence, and abscission (1). The analysis of growth hormones is very important depending on the development of biostimulant science (2). It is considerably difficult to analyze phytohormones due to their very low presence in plant tissue in addition to the availability of excessive amounts of interfering substances (e.g., proteins, carbohydrates, pigments and lipids). The courses of extraction and purification of plant tissues are at least as important steps as the determination method because the accuracy and precision of an analysis are based on the sample preparation phase (3). The solvent used for extraction should effec- tively extract the analyte without excluding too much interfering material from plant tissue. The most commonly used solvents for Downloaded from https://academic.oup.com/chromsci/advance-article-abstract/doi/10.1093/chromsci/bmz074/5611274 by guest on 11 February 2020