U Se Of Solid-Phase Micro-Extraction As a Sampling

Journal of Chromatography A, 998 (2003) 229–233 www.elsevier.com / locate / chroma

Short communication

Use of solid-phase micro-extraction as a sampling technique in the determination of volatiles emitted by flowers, isolated flower parts and pollen q
Guido Flamini*, Pier Luigi Cioni, Ivano Morelli
Dipartimento di Chimica Bioorganica e Biofarmacia, Via Bonanno 33, 56126 Pisa, Italy Received22 May 2002; received in revised form 21 February 2003; accepted 7 April 2003

Abstract The volatiles emitted by fresh whole flowers or isolated flower parts of mandarin, Citrus deliciosa Ten. (Rutaceae), were sampled using solid-phase micro-extraction (SPME). This technique offers several advantages over dynamic headspace sampling techniques used in previous investigations. In particular, SPMErequires smaller sample sizes and very short sampling times, which can minimize the formation of artifacts due to damage to the plant, and contaminations or loss of compounds. This was especially applicable to the collection of volatiles from pollen.  2003 Elsevier Science B.V. All rights reserved. Keywords: Pollen; Flowers; Citrus deliciosa; Solid phase micro-extraction; Volatiles

1.Introduction It is known that the color of a flower is the first and foremost cue for pollinator’s attraction, but the scent of a flower also plays a major role in attracting pollinating insects [1,2]. The use of headspace technique to sample volatiles in the air surrounding a whole plant or plant organ has permitted one to ascertain that olfactory floral stimuli differ not only between species, but alsobetween different organs within a single flower [3–8]. Distinctive volatile compounds could allow insects both to recognise specific host plants and to assess the amount of rewards in a flower, since pollen, an important food
In memory of Professor Serena Catalano, 1945–2002. *Corresponding author. Fax: 139-05-043-321. E-mail address: flamini@farm.unipi.it (G. Flamini).
q

source for many flower-feedinginsects, also produces odors [1]. Studies of floral scents and of their patterns within a single flower are important to better understand the chemical bases of plant–animal relationships and pollination ecology. Furthermore, they may reveal new scented molecules that could be of value to both the food industry and perfumery. Many papers deal with the analysis of flower volatiles, which are sampledmainly by means of dynamic headspace techniques [9–11]. Recently, papers have addressed the use of solid-phase micro-extraction (SPME) as a sampling technique [7,12–14], and the performance of different SPME fiber coatings for sampling the headspace of four aromatic and medicinal plants has been compared [15]. The floral scent sampling techniques employed in previous studies have the drawbacks ofrequiring

0021-9673 / 03 / $ – see front matter  2003 Elsevier Science B.V. All rights reserved. doi:10.1016 / S0021-9673(03)00641-1

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G. Flamini et al. / J. Chromatogr. A 998 (2003) 229–233

considerable amounts of flower material, especially when sampling volatiles from pollen (50–200 mg), and very long sampling times (24–48 h for pollen, or 8–27 h for flower parts), as well as posingpossible risks of sample contamination and loss of volatiles during the concentration of the solvent–volatile mixture in a water-bath in preparation for analysis by GC [4–6]. We have improved upon these sampling methods, and here we report the application of the SPME technique to collect the volatiles emitted by whole fresh flowers and different flower parts of mandarin (Citrus deliciosa Ten.,Rutaceae).

2. Materials and methods Flowers were picked from cultivated plants of Citrus deliciosa and immediately submitted to volatile collection. Five different samples were prepared: Sample 1. Whole flowers (including sepals, petals, stamens and gynoecium). Three flowers were collected just after flower opening, cut a few mm below the calix, and the pedicels were wrapped in aluminium foil to...