USDA-ARS Research Project number 6036-22000-028-00D. The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the United States Department of Agriculture or the Agriculture Research Service of any product or service to the exclusion of others that may be suitable. Additionally, the University of Florida Biology Department-Lewis and Varina Vaughn Fellowship in Orchid Biology (2017), and a University of Florida Graduate Research Fellowship (2014-2018) provided funding as well. We also thank Cindy Bennington from Stetson University for the orchid plant used during filming of this video.

NOTE: Perfumes or scented lotions and products must not be worn during any of these procedures.
1. Flower selection
NOTE: Flowers used can be either naturally growing in the environment or kept under artificial environmental conditions. Temperature, humidity, and light level during collection can vary based on the specific flower species used, and what type of data is being collected. For example, data has been collected during the day and at night for the same flower...

<ol>
	<li>Knudsen, J. T., Tollsten, L., Bergstrom, L. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Floral+scents-+A+checklist+of+volatile+compounds+isolated+by+head-space+techniques.">Floral scents- A checklist of volatile compounds isolated by head-space techniques.</a> Phytochemistry. 33, 253-280 (1993).</li><li>Dudareva, N. A., Pichersky, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Biology of floral scent. , (2006).</li><li>Altenburger, R., Matile, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rhythms+of+fragrance+emission+in+flowers.">Rhythms of fragrance emission in flowers.</a> Planta. 174, 242-247 (1988).</li><li>Dodson, C. H., Dressler, R. L., Hills, H. G., Adams, R. M., Williams, N. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biologically+active+compounds+in+orchid+fragrances.">Biologically active compounds in orchid fragrances.</a> Science. 164, 1243-1249 (1969).</li><li>Theis, N., Raguso, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+pollination+on+floral+fragrance+in+thistles.">The effect of pollination on floral fragrance in thistles.</a> Journal of Chemical Ecology. 31 (11), 2581-2600 (2005).</li><li>Heath, R. R., Manukian, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+evaluation+of+systems+to+collect+volatile+semiochemicals+from+insects+and+plants+using+a+charcoal-infused+medium+for+air+purification.">Development and evaluation of systems to collect volatile semiochemicals from insects and plants using a charcoal-infused medium for air purification.</a> Journal of Chemical Ecology. 18, 1209-1226 (1992).</li><li>Cancino, A., Damon, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+floral+fragrance+components+of+species+of+Encyclia+and+Prosthechea+(Orchidaceae)+from+Soconusco,+southeast+Mexico.">Comparison of floral fragrance components of species of Encyclia and Prosthechea (Orchidaceae) from Soconusco, southeast Mexico.</a> Lankesteriana. 6, 83-139 (2006).</li><li>Cancino, A., Damon, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fragrance+analysis+of+euglossine+bee+pollinated+orchids+from+Soconusco,+south-east+Mexico.">Fragrance analysis of euglossine bee pollinated orchids from Soconusco, south-east Mexico.</a> Plant Species Biology. 22, 129-134 (2007).</li><li>Sadler, J. J., Smith, J. M., Zettler, L. W., Alborn, H. T., Richardson, L. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fragrance+composition+of+Dendrophylax+lindenii+(Orchidaceae)+using+a+novel+technique+applied+in+situ.">Fragrance composition of Dendrophylax lindenii (Orchidaceae) using a novel technique applied in situ.</a> European Journal of Environmental Science. 1, 137-141 (2011).</li><li>Ray, H. A., Stuhl, C. J., Gillett-Kaufman, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Floral+fragrance+analysis+of+Prosthechea+cochleata+(Orchidaceae),+an+endangered+native,+epiphytic+orchid,+in+Florida.">Floral fragrance analysis of Prosthechea cochleata (Orchidaceae), an endangered native, epiphytic orchid, in Florida.</a> Plant Signaling and Behavior. , (2018).</li><li>. National Institute of Standards and Technology. U.S. Department of Commerce Available from: <a target="_blank" href="https://www.nist.gov/">https://www.nist.gov/</a> (2019)</li></ol>

Though this technique is incredibly valuable for its sampling speed and portability, one limitation is using it for epiphytic species, or those growing on trees and not from the ground. In the original study10, one of the flowers sampled was epiphytic. Because the machine is too heavy to hang freely, a stable, elevated base must be made for sampling. Additionally, the machine can either be plugged in to an electrical outlet or battery powered, so if there is prolonged field sampling, there must be...

Flowers typically produce a fragrance used to attract pollinators. These fragrances are made up of many chemical compounds all acting together as a floral blend1,2,3. Without these fragrances, flowers would be less likely to pass on their genetic information using pollinators. Floral fragrance has been documented in many flowering plant families, with Orchidaceae being one of the more common families studied4. To understand the role of floral fragrance in pollination, it is important to nondestructively collect and analyze the chemical compounds being emitted from the flowers at different times of the day and during the several days to weeks the flower blooms are open, as fragrance can vary over time5.
An early protocol for this kind of sampling was developed by Heath and Manukian6. The goal of their sampling methods was to reduce stress on the specimen (e.g., plants, insects) being studied. Earlier papers documented that destructive procedures to the plant were required, such as removing blooming flowers in order to collect the fragrance. More recent floral fragrance publications by Cancino and Damon7,8 used similar methods. This study put the flowers in glass chambers and passed purified air over them; then fragrance compounds from the chamber were absorbed onto porous polymer adsorbents in clear Pasteur pipettes. The fragrances were collected for at least two hours during this study. Sadler et al.9 carried out floral fragrance studies on an epiphytic orchid in south Florida, much like the original study10. Again, this study required the flowers to be sampled for over two hours to collect the fragrance volatiles, with fragrance collected onto the porous polymer adsorbent. The paper here presents a non-destructive method that allows for much quicker sampling, lasting only 10 minutes. Also, instead of using a glass chamber oven baking bags are used, which allow for more flexible movement of the chamber and reduce the chances of damage to the flowers. These bags come in several sizes allowing the option to select the size of bag that will easily fit individual samples without damaging the sample or the surrounding material. The adsorbent used in this study was Tenax Porous Polymer Adsorbent. This differs from Porapak, because the sample can be thermally desorbed onto the GC-MS column for analysis, eliminating the use of a chemical solvent.
The methods in this study provide a way to quickly sample fragrance volatiles produced by flowers and could be used to sample volatiles from other specimens as well, such as insect pheromones, or mushroom volatiles. The reduced time for sampling means there is less stress on the sample and the ability to collect many samples in a short period of time. For example, in Sadler et al.9, the flower was only fragrant at night, so only two or three samples could be collected each night. With the method here, samples could be taken all night at 15-20-minute intervals from the same flower. Additionally, by using bags instead of glass chambers, the headspace can be suspended easier for sampling in the field for in situ collection on endangered or threatened plant species. Using the method presented here, we were able to sample flowers 1.5 to 2 meters above ground. These methods are incredibly useful for fragrance collection in the laboratory and the field, and provides researchers with a sampling technique that is fast and non-destructive to the sample.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Bulkhead Union</td>
			<td>Cole-Palmer</td>
			<td>UX-06390-10</td>
			<td></td>
		</tr>
		<tr>
			<td>FEP tubing</td>
			<td>Cole-Palmer</td>
			<td>UX-06407-60</td>
			<td></td>
		</tr>
		<tr>
			<td>Gas Chromatography</td>
			<td>Hewlett Packard</td>
			<td>6890</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass Wool, Silanized</td>
			<td>Sigma-Aldrich</td>
			<td>20411</td>
			<td></td>
		</tr>
		<tr>
			<td>Inlet liner</td>
			<td>Agilent</td>
			<td>5062-3587</td>
			<td></td>
		</tr>
		<tr>
			<td>Mass Spectrometer</td>
			<td>Hewlett Packard</td>
			<td>5973</td>
			<td></td>
		</tr>
		<tr>
			<td>Reynolds oven bag</td>
			<td>Reynolds Consumer Products</td>
			<td>Turkey size</td>
			<td></td>
		</tr>
		<tr>
			<td>Tenax Porous Polymer Adsorbent</td>
			<td>Sigma-Aldrich</td>
			<td>11982</td>
			<td></td>
		</tr>
	</tbody>
</table>

rapid collection of floral fragrance volatiles using a headspace volatile collection technique for gc-ms thermal desorption sampling

Fragrances of many flower families have been sampled and the volatiles analyzed. Knowing the compounds that make up the fragrances can be an important step to conservation of flowers that are threatened or endangered. Because floral fragrance is critical for attracting pollinators, this method could be used to better understand or even enhance pollination. We present a protocol using a portable charcoal air filter and vacuum to collect floral fragrance volatiles, which are then analyzed by a GC-MS. By using this method, fragrance volatiles can be sampled using a non-destructive method with a machine that is easily transported. This methodology uses a rapid sampling procedure, cutting sampling time down from 2-3 hours to approximately 10 minutes. Using GC-MS, the fragrance compounds can be identified individually, based on authentic standards. The steps used for collecting fragrance and control data are presented, from material setup to collecting the data output.

Representative data from the GC-MS are shown as a chromatogram in Figure 1. In addition to the chromatogram, a data file of results is also provided (Supplementary File 1). This data file provides the retention time for each peak (RT), and an identification of what compound that peak is (Library/ID). Peaks between 10:00 and 15:00 minutes are floral volatiles, due to the molecular weight of the compounds10. The numbers above the peaks signify the reten...

Watch this Scientific Journal Video about Rapid Collection of Floral Fragrance Volatiles using a Headspace Volatile Collection Technique for GC-MS Thermal Desorption Sampling at JoVE.com

Rapid Collection of Floral Fragrance Volatiles using a Headspace Volatile Collection Technique for GC-MS Thermal Desorption Sampling

Here, we present a protocol for collecting the floral fragrance volatiles from blooming flowers, using a non-destructive sampling procedure.

Fragrances of many flower families have been sampled and the volatiles analyzed. Knowing the compounds that make up the fragrances can be an important ...

Because floral fragrance is critical for attracting pollinators, this method could be used to better understand or even enhance pollination of native flower species. With this method, fragrance volatiles are sampled using a non-destructive method with an easily-transported machine. This methodology uses rapid sampling, cutting sampling time from two to three hours to 10 minutes.These methods provide a way to quickly sample volatiles produced by flowers and could be used to sample volatiles from other specimens as well, such as insect pheromones. To begin, select a flower that is initially unopened, and mark the flower with flagging tape to ensure repeated sampling of the same flower. Boil oven bags in water for 30 minutes to remove residual plastic compounds.To dry, bake in an oven at 175 degrees Celsius for 60 minutes. Once the bags have dried, add a polypropylene bulkhead union to each corner of the closed end of the oven bags. Rinse all bags and tubes with 75%ethanol and let them air dry.Then, bake the bags and the tubes in an oven at low heat, between 74 to 85 degrees Celsius for 30 minutes. Depending on the duration of the blooming time, if possible wait at least 24 hours after blooming to collect the sample. Cover the selected flower with a baked oven bag.Cinch the bag together tightly with a plastic zip tie below the flower to prevent unwanted air flow into the bag. Wearing sterile neoprene gloves, attach a tube from the air outlet of the collection equipment and connect it to one of the bulkhead unions on the oven bag. On the other bulkhead union, attach a glass filter cartridge containing porous polymer adsorbent.Attach a second tube to the collection equipment on the vacuum input. Connect the end of the second tube onto the glass volatile collection filter cartridge. Turn on both the air pump and the vacuum at the same time and set at 0.05 liters per minute.The head space around the flower is filled with air but not overinflated. The system pulls air from the bag through the filter, trapping the floral volatiles. Allow the machine to run for 10 minutes.And then turn off both the air pump and vacuum. Disassemble the tubes and the glass filter cartridge. Place the filter into a glass vial and screw on a cap.Seal the vial with PTFE pipe thread tape. Store the sample in a freezer until GCMS analysis. Repeat this process with an empty oven bag to collect a blank air sample as a control.For consistent replications of the same volatiles, repeat sample collection at the same time each day, as some flowers produce varying fragrance levels over the course of the day. First, remove the glass filter cartridge from the freezer and place it into a GCMS in the injector port. To release head space volatiles collected on porous polymer adsorbent from the adsorbent, heat the thermal collection trap to 220 degrees Celsius for eight minutes within a flow of helium gas at 1.2 milliliters per minute.Compare chromatograms of collected volatiles to identify common reoccurring peaks. After identifying the peak volatiles, use Pherobase to determine if they have been previously described in floral fragrances. In this study, representative data from the GCMS are shown as a chromatogram.Peaks between 10 and 15 minutes are floral volatiles. The collected volatiles were referenced in Pherobase to determine if they have been previously described in a floral fragrance. For example, compound number 21, with a retention time of 10.311 has been identified as benzaldehyde.Benzaldehyde is searchable on Pherobase with a list of all flower species, organized by plant family, from which that fragrance compound has been identified. The orchid species are shown here, from which benzaldehyde has been determined to be present in the floral fragrance. Previous methods took two to four hours per sample.The use of a solvent to remove the sample from the filter would result in a solvent peak on the GCMS. This would hide the compounds from zero to 3.5 minutes. This method allows for all compounds to be seen.

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Research

JoVE Journal

Biochemistry

6.7K visualizações.  University of Florida. Como a fragrância floral é fundamental para atrair polinizadores, este método poderia ser usado para entender melhor ou até mesmo melhorar a polinização de espécies de flores nativas. Com este método, os voláteis de fragrâncias são amostrados usando um método não destrutivo com uma máquina facilmente transportada. Esta metodologia utiliza amostragem rápida, reduzindo o tempo de amostragem de duas a três horas para 10 minutos.Esses métodos fornecem uma maneira de amostr...