Headspace Method Research Articles

Comparison of the volatiles composition between healthy and buprestid infected Juglans regia (Juglandaceae)

Meliboeus ohbayashii primoriensis (Coleoptera: Buprestidae) is an important pest of the walnut tree Juglans regia (Juglandaceae), but the volatiles mediating this plant–herbivore interaction are unknown. In this study, volatiles emitted by healthy J. regia and by plants infested with M. ohbayashii primoriensis (Coleoptera: Buprestidae) were obtained by a dynamic headspace method and analyzed by gas chromatography-mass spectrometry (Shanxi, China). We identified 26 major compounds and compared the volatile composition of healthy and buprestid-infected J. regia. Green leaf volatiles were detected in all damaged plants, including the monoterpenoids β-phellandrene and (E)-β-ocimene, the sesquiterpenoids (-)-β-bourbonene, β-ylangene, and (E,E)-α-farnesene, the alcohols linalool, myrtenol, and (E)-(-)-pinocarveol, the ketones (E)-pinocamphone and (Z)-pinocamphone, and the ester methyl salicylate. The major volatiles detected in healthy plants were β-pinene (36.26 %), α-pinene (23.81 %), D-limonene (12.03 %), sabinene (8.63 %), and β-myrcene (4.35 %). The main volatiles from M. ohbayashii primoriensis larva-infested plants were β-pinene (37.82 %), α-pinene (20.36 %), D-limonene (14.71 %), germacrene D (5.24 %), sabinene (4.52 %), and β-phellandrene (3.80 %). These results enrich our understanding of volatiles of healthy plants and plants infested with M. ohbayashii primoriensis. Furthermore, they provide a theoretical basis and scientific foundation for integrated pest management and for effective ecologically sustainable pest control strategies.

Direct Mass Spectrometry with Online Headspace Sample Pretreatment for Continuous Water Quality Monitoring

This study investigates the use of selected ion flow tube mass spectrometry with an automated headspace pretreatment system for the continuous surveillance of water quality at wastewater treatment plants (WWTPs) and rivers. The reaction rates of the target compounds introduced using the headspace method were similar to those of the mass scan library, with a margin of error of <10%. Novel quantitative formulae were derived for the water samples of the target compounds, and the linearity of the calibration curves for both the purified and effluent matrix (0.1–2.0 mg/L) showed a coefficient of determination of 0.98–0.99 for most compounds. The detection limit for 74% of the target substances was 0.02–0.10 mg/L, and the average recoveries were 111.6% and 104.7% for the low- and high-concentration spiked samples, respectively, which are comparable to those of the headspace gas chromatography-mass spectrometry system. However, the variability in individual concentrations was still large, due to the unstable control of sample injection flow and pressure. Herein, 79% of the 28 compounds met one-tenth of the proposed method detection limit criteria for emergency operations in WWTP. Field experiments showed that the system was easy to maintain and could be used to monitor chemical accidents.

Sexual dimorphism in floral scents of the neotropical orchid Catasetum arietinum and its possible ecological and evolutionary significance

Abstract Dioecy in angiosperms is often associated with sexual dimorphism in floral traits other than the sexual organs. Species of the neotropical orchid genus Catasetum produce unisexual flowers characterized by a remarkable morphological sexual dimorphism. Catasetum species emit strong floral perfumes that act as both signal and reward for male euglossine bee pollinators. Although the role of floral perfumes of Catasetum in attracting euglossine pollinators is well investigated, little is known about whether perfumes differ between floral sexes and, if they do, whether this chemical dimorphism influences the pollination ecology of the plants. Taking Catasetum arietinum as a model species, our aim was to observe the behaviour of pollinators on male and female flowers and to compare scent properties (i.e. chemical composition, total amount and temporal fluctuation) of male and female flowers. Floral scent samples were collected by using dynamic headspace methods and were analysed via gas chromatography coupled with mass spectroscopy (GC-MS). Catasetum arietinum is pollinated by males of two Euglossa species (i.e. E. nanomelanotricha and E. securigera). Bees approached male and female inflorescences of C. arietinum in similar proportions but landed significantly more often and spent more time on female flowers, which emitted more scent than male flowers. Furthermore, the amount of scent emitted varied across the different times of sampling, corresponding to the pattern of the diel foraging activity of pollinating bees on male and female flowers. The chemical composition of scents differed significantly between sexes. The two major compounds (Z)-methyl-p-methoxycinnamate and (E)-geranyl geraniol contributed most to this difference. This is the first case of sexual dimorphism reported in orchid floral perfumes. We discuss the influence of sex-specific floral scents on the behaviour of euglossine pollinators and offer new insights into the ecological and evolutionary significance of divergence in floral scents among dioecious plants.

Studies on the Measurements of Sulfides in Landfill Leachate and Other Water Samples Using the Headspace Method

最終処分場浸出水等から放出される可能性のある硫化水素を簡便に現場で測定するためのヘッドスペース法の測定容器を考案した．実験は水試料を入れたプラスチックの密閉容器を振とうしてガスを放散させ，気相中の硫化水素濃度の検知管による測定方法について検討した．その結果，気相を採取する際に外気を容器底部に導入しながら行う方法が良好であった．本法の再現性を確認するとともに溶存硫化物濃度，pH 値などとの関連性を調べた．

Determination of the Light Hydrocarbons in Sediment Porewater from the Black Sea by Gas Chromatography (GC)

A sensitive and selective gas chromatographic (GC) method has been developed for the determination of dissolved methane, ethane, propane butane, pentane and hexane in seawater from sediment pores. For this purpose, a headspace method was developed. The dissolved methane concentrations in the liquid phase were calculated using Henry’s Law and in the gas phase using a partial pressure measurement. The method requires minimal sample preparation and provides low ng/L detection limits. The samples were collected from Black Sea bottom sediment porewaters.

Correlation between formaldehyde emission characteristics in enclosed desiccators with five different geometries

The static headspace method using a small enclosed chamber has been extensively used to estimate the emission characteristics of formaldehyde, e.g., emission rates from building materials. The formation of the transient formaldehyde concentration by emission, diffusion and sorption in a small confined chamber was investigated using three-dimensional modelling and numerical analyses. Here, five types of glass desiccators were adopted as the small chamber for the headspace method. The inner geometries of the desiccator with the emission source (the building material) and sorbent (water in a Petri dish) were precisely modelled. Transient numerical analyses were performed to determine the formaldehyde emission from different building materials of the external (evaporative) diffusion control type, molecular diffusion and sorption on the water in the confined desiccators. In order to clarify the effect of the desiccator inner geometry on the formaldehyde emission characteristics, the equivalent diffusion length ( Ld) concept, which could be identified as the representative one-dimensional diffusion length scale, was proposed. The results of the numerical analyses showed that Ld and the formaldehyde concentration in the sorbent solution over a 24 h numerical experiment were significantly affected by the desiccator geometry. These results confirmed that the calibration of the emission rate with external diffusion control using Ld is appropriate when measuring the formaldehyde emission rate in an enclosed desiccator with different geometries.

Determination of Molecular and “Truly” Free Sulfur Dioxide in Wine: A Comparison of Headspace and Conventional Methods

Conventional methods such as Ripper titration and aeration-oxidation (A-O) are widely used for the analysis of sulfur dioxide (SO2) in wine. However, the free SO2 reported by these procedures is overestimated due to dissociation of weakly bound SO2 forms during the analysis, particularly from anthocyanin-bisulfite complexes. “Truly” free SO2 in wine can be determined from the headspace SO2 concentration of an equilibrated wine sample. A headspace SO2 method based on gas detection tubes (HS-GDT) was recently described but is not readily automated. While solid phase microextraction (SPME) yielded poor precision in our experiments, our new method, based on static headspace gas chromatography and sulfur chemiluminescence detection (HS-GC-SCD), is readily automated and achieves high precision (

Phosphine detection in veterinary samples using headspace gas chromatography/tandem mass spectrometry with multiple reaction monitoring.

Determination of phosphine exposure from zinc or aluminum phosphide fumigants continues to be a routine analytical requirement in veterinary forensic toxicology. There is a need for a more reliable and specific method than simple gas chromatography/mass spectrometry (GC/MS) analysis of sample solvent extracts, as GC/MS of extracts on capillary columns used for general screens involves significant interference from air peaks. GC/MS/MS headspace analysis of acid-generated phosphine gas enabled study of the feasibility of devising multiple reaction monitoring (MRM) approaches to the determination of phosphine with greater specificity. Collision-induced dissociation in GC/MS/MS showed that phosphine generated m/z 34 → 31, 32 and 33 ion transitions by sequential proton release as well as minor transitions m/z 34 → 47, 34 → 63 and 63 → 31.5 by intermolecular collisions and double charging. Study of the formation of these product ions enabled development of MRM settings for a highly useful headspace method for phosphine detection. The method was validated over a working range of 5-100 ppm of phosphide generating phosphine gas which enabled retention of regular screen capillary columns without necessitating separation from air components. The method should have adequate sensitivity and reliability for veterinary toxicology laboratories confronting specimens from animals poisoned by crop fumigants.

Male-Produced (-)-δ-Heptalactone, Pheromone of Fruit Fly Rhagoletis batava (Diptera: Tephritidae), a Sea Buckthorn Berries Pest.

The plantation area of sea buckthorn (Hippophae rhamnoides L.) is expanding in many European countries due to increasing demand for berries, thus creating suitable conditions for the rapid expansion of the fruit fly Rhagoletis batava, a pest of economic importance. To decrease insecticide use, effective means for pest population monitoring are required, including the use of pheromones. Male fruit flies emit (-)-δ-heptalactone as revealed by gas chromatography-mass spectrometry analyses of samples obtained using headspace methods. The two enantiomers of δ-heptalactone were synthesized using enantioselective synthesis. A gas chromatography-electroantennographic detection analysis of both stereoisomers revealed that only (-)-δ-heptalactone elicited electrophysiological responses, whereas no signal was registered to (+)-δ-heptalactone in fruit flies of either sex. In the field assay, traps baited with (-)-δ-heptalactone caught significantly more fruit flies compared with the unbaited traps. Our results are the first to demonstrate the efficacy of (-)-δ-heptalactone as a bait for trapping R. batava. As a behaviorally attractive compound to R. batava fruit flies of both sexes, (-)-δ-heptalactone is attributed to aggregation pheromones. This is the first report of an aggregation pheromone within the genus Rhagoletis.

GCMS Analysis of Bioactives of Piper betle Linn. Leaf

Background: Piper betle Linn. (Piperaceae) is commonly known as “Green gold of India” due to its high commercial value. It is a Vedic plant used in various traditional system of medicine v.iz. Ayurveda system of medicine, Yunani system of medicine attributed to various pharmacological activities v.i.z. antioxidant, anti-inflammatory, analgesic, anti-fertility, antimutagenic etc. Objectives: The main objective of the present study is quantitative estimation of the various bioactive compounds present in leaf of P. betle L. (Bangla variety) by GC-MS analysis using head space method. Material and Methods: The vapor sample of leaf of P. betle L. was prepared by head space method for GCMS analysis. GCMS analysis was carried out using high resolution Thermo scientific TSQ 8000 Gas Chromatograph-Mass Spectrometer. Helium is used as carrier gas (99.999 %) with a constant flow rate of 1 ml/min. Total run time was 29.10 min. Results: GC-MS analysis revealed the presence of 16 bioactive compounds in leaf of P. betle L. Eugenol (29.13%), Bakuchiol (11.79%) and α-linalool (14.88%) are the chief bioactive compounds of leaf. Leaf has been also reported to contain a good percentage of various terpenoids like β- caryophyllene (7.69), α-muurolene (4.19), α-bisabolene (0.98), etc. Conclusion: From GC-MS analysis results it can be concluded that leaf of P. betle L. is a reservoir of valuable phenolic and susquiterpene compounds. Eugenol chief biomarker compound present leaf is a versatile remarkable molecule. Due to number of phytoconstituents P. betle L. leaf is recommended as plant of phytopharmaceutical importance.

Headspace volatiles isolated from twigs of Picea omorika from Serbia

The variability of volatiles isolated from twigs by the static headspace (HS) method in seven natural populations of Picea omorika from Serbia was investigated for the first time. In the overall chemical profile, monoterpenes strongly dominated hydrocarbons as the most volatile compounds (95.7%). The dominant compounds were ?-pinene (29.5 %), ?-pinene (25.7%) and myrcene (13.0%), totaling 68.2% of the volatiles on average. The following nine volatiles were found to be present in medium-to-high amounts (0.5-10%): tricyclene, camphene, ?-phellandrene, ?-3-carene, p-cymene, ?-phellandrene, terpinolene, (E)-caryophyllene, and germacrene D. Out of the 78 volatiles detected, the six most abundant (?-pinene, ?-pinene, myrcene, ?-3-carene, ?-phellandrene and camphene) were selected for principle component analysis (PCA) and cluster analyses (CA). PCA revealed a high degree of similarity between populations, while CA showed a degree of separation of two populations from the others. The presented results are in agreement with previous phytochemical and molecular analyses of this species that confirm high variability in both specialized metabolites and genetic markers.

Hydrocarbon gases in seafloor sediments of the TATAR strait, the northern sea of Japan

The distributions of hydrocarbon gases (HCGs) from C1-C5 in seafloor sediments of the South Tatar sedimentary basin (northern Sea of Japan) were obtained during five research cruises from 2012 to 2017. As a result of this work, areas of gas hydrates, gas flares, and anomalous gas concentrations were discovered. The concentration of HCGs in seafloor sediment, as determined by the “headspace method” varied from 0.38 to 149,000 ppm, with a median of 177 ppm (N = 1420). The median values of HCGs for the Western, Central, and Eastern part of the South Tatar sedimentary basin are 11.7, 99, and 1134 ppm, respectively. Maximum values and gradients in concentrations of HCGs were found in the central and eastern parts of Tatar Strait, where multiple cores contain gas hydrates and gas-saturated sediments. The predominant gas component in all samples was methane, but relatively high concentrations of ethane (up to 789 ppm) and propane (up to 111 ppm) occur. Methane concentrations below 5.25 ppm can be considered as regional background for near seafloor (0–15 cm) sediments from the South Tatar sedimentary basin. The С1/(С2 + С3) ratio across all samples ranges between 2.6 and 345,000, with a median value of 219. The presence of a large-scale degassing zone exists in the northeastern part of Tatar Strait, which coincides with areas of gas hydrates and gas anomalies in the sediments and gas flares in the water column.

Seasonal and spatial variation in total trihalomethane formation potential in groundwater in Tulkarm and Hebron, Palestine

Water disinfection using processes such as chlorination is required to kill bacteria and harmful biological components. During chlorination, organic components in water react with chlorine, forming harmful disinfection by-products such as trihalomethanes (THMs). These compounds are very harmful to humans, animals, and plants. Thus, the concentration of these substances in groundwater as well as the seasonal variation in this concentration are of immense interest to scientists. A headspace method was used to analyze trihalomethanes (THMs) using an Agilent 6890N GC/MS. Five-milliliter water samples were employed in this analysis. Separation was performed on a J&W-VRX column. A selected ion monitoring (SIM) mode that complied with US EPA method no. 501 was developed for the detection of four THM species. Quantification and method validation were performed using external standard calibration. The total trihalomethane formation potentials (TTHMFPs) in four groundwater wells in the summer and the winter were found to be below the maximum limits specified by environmental agencies. Seasonal variations were more pronounced for the formation of chloroform (CF), which was the dominant THM species formed. The fraction of the TTHMFP that was due to CF increased in the winter in groundwater samples from the Anabta (2), Anabta (3), and Al Rehya wells, whereas the fraction of the TTHMFP that was due to CF was almost the same in summer (43.2%) and in winter (40.3%) in the groundwater samples from the Al Fawar well. These findings are important for the appropriate regulation of THM levels and for achieving a better understanding of environmental public health and epidemiological issues concerning disinfection by-products in Palestine.

Multiple headspace sampling coupled to a programmed temperature vaporizer to improve sensitivity in headspace-gas chromatography. Determination of aldehydes

The improvement of sensitivity in headspace (HS) sampling of not very volatile analytes constitutes a challenge that has usually been approached through coupling with additional techniques. Here we propose a new methodology for increasing sensitivity through a multistep approach. This proof of concept is based on direct coupling of a headspace sampler with a programmed temperature vaporizer (PTV) and a gas chromatograph (GC), with mass spectrometry (MS) detection. Analytes are extracted from the same vial in a stepwise procedure, splitting the headspace generation time of conventional HS into four periods and using the PTV to cryogenically trap the analytes during the successive HS samplings. Solvent vent mode is mandatory in order to retain the analytes, purging the gas solvent at an adequate initial low temperature and flash-heating the PTV liner in a quick ramp (720 °C/min), once the HS samplings are finished. Linear aldehydes, from pentanal to decanal, possible biomarkers of several diseases have been selected as model compounds. This multiple HS method has been compared with conventional HS, and it has been validated in terms of linearity, limits of detection, repeatability, reproducibility and accuracy. The limits of detection (LOD) ranged from 0.004 to 0.159 µg/L. Enrichment factors (EF) in relation to the conventional HS method ranged from 3.0 to 6.7, except for pentanal (EF: 0.8), which is too volatile and polar to be trapped in the PTV with the multiple HS methodology. Similar enrichment factors were obtained in a urine sample.

Distribution of transient formaldehyde concentration in confined small glass desiccators and its impact on emission rate measurement

The headspace method is used frequently for measuring the emissions rates of chemical compounds from building materials when operating labeling systems for these materials. A numerical investigation of transient formaldehyde concentration distribution in confined small glass desiccators was conducted in this study. To clarify the impact of the desiccator geometry on the formaldehyde emission and diffusion characteristics, three-dimensional (3D) laser-based measurement was first conducted to define the detailed inner geometries of the different commercial desiccators. A petri dish containing water was used as the sorbent for test specimens of formaldehyde emission sources produced inside the desiccators. Fundamental experiments concerning formaldehyde emission rates and sorption onto the sorbent were next performed using high- and low-emission types of building materials in the desiccators. Transient and steady numerical analyses were conducted for formaldehyde emissions from the building materials, molecular diffusion, and sorption onto the water sorbent. Transient analysis of the formaldehyde diffusion field over 24 h revealed that the total amount of dissolution of formaldehyde in the water was not significantly affected by the desiccator geometry in the building material of the inner diffusion control type. For evaporative/external diffusion emission-type, however, the formaldehyde emission rate was strongly affected by the desiccator shape. To obtain reproducible emission rate measurements in desiccators with different geometrical shapes, substantial adjustment is needed for the relative positions of the emission source and the sorbent in terms of the equivalent diffusion length, Ld.

Greenhouse gas emissions from a sewage contact oxidation emergency treatment plant after destruction by an earthquake and tsunami

Emissions of greenhouse gases (GHGs) from a full-scale contact oxidation emergency sewage treatment plant (STP) in Japan that was damaged by an earthquake and a tsunami were measured. The open chamber (OC) and closed chamber (CC) methods were used to sample the gases emitted in the aeration tank and the settler, respectively. The dissolved gases were measured using the headspace method, and the major emissions sources in wastewater treatment were identified. The results indicated that the GHG emissions from the wastewater were 58.6 g-CO2/m3 (equivalent per cubic meter of wastewater). The CH4 emissions showed a strong negative correlation with the dissolved oxygen (DO) content. More than 98% of the GHGs were produced and stripped by the aeration tank. The CO2, CH4 and N2O emissions accounted for 73.0% (21,781 mL/m3), 17.1% (669 mL/m3) and 9.9% (10.9 mL/m3), respectively, of all GHG emissions. Approximately 1.06% of the incoming chemical oxygen demand (COD) was emitted as CH4, and 0.147% of the removed nitrogen was emitted as N2O.

Abundance, activity and diversity of methanotrophic bacteria in the Elbe Estuary and southern North Sea

Shelf sea areas are the primary oceanic source for methane release, the most abundant hydrocarbon in the atmosphere. As such, the southern North Sea’s methane concentration is mainly determined by river runoff and tidal marshes. Within such a highly variable temperate estuary, this study is the first to reveal detailed information on the in situ activity, abundance and community structure of methane oxidizing bacteria along a transect from the marine environment near Helgoland island to the riverine harbor of Hamburg, Germany. The in situ methane oxidation rate was determined with a radio tracer, and methane concentration with the head-space method. Abundance and diversity of the methanotrophic bacterial community in the water column was assessed with quantitative polymerase chain reaction for the particulate methane monooxygenase and monooxygenase intergenic spacer analysis. Median abundances ranged from 2.8 × 104 cells l−1 in the marine environment to 7.5 × 105 cells l−1 in the riverine environment. Except for salinity, no conclusive linear correlation between any environmental parameter and the abundance of methanotrophs could be determined. Relating activity with abundance of methanotrophs showed that about 70% of the population is inactive, especially in the coastal and marine environment. This study found distinct operational taxonomic unit (OTU) community compositions among the 3 environmental categories (river, coast, marine). Several identified OTUs have been reported previously and imply a wide geographic occurrence. Overall, we propose that salinity is the most important driver of differing communities in the riverine, coastal and marine environment.

Chemical Compositions of the Essential Oils and Headspace Volatiles of Seseli peucedanoides Plant Parts

The chemical compositions of the essential oils of Seseli peucedanoides (M.Bieb.) Koso-Pol. inflorescences and leaves, isolated by hydrodistillation, and headspace volatiles, obtained by the static headspace method, were analyzed in detail by gas chromatography (GC) and GC/mass spectrometry (MS). In total, 74 constituents were identified, representing more than 98% of the observed GC peaks. The number of identified essential oil components obtained from the inflorescences was 63 while for the leaf essential oil it was 46. A much smaller number of compounds, 26 for inflorescences and 21 for leaves, were detected in the headspace samples. In both essential oils the most abundant compounds were the same, ( E)-caryophyllene and germacrene D, only in different proportions. The main components in the headspace specimens were α-pinene and ( E)-β-ocimene with ( E)-caryophyllene and ( Z)-3-hexen-1-ol also determined in significant percentages. The major class of compounds identified in the investigated essential oils was hydrocarbon sesquiterpenes with a share of over 80%, while the most dominant class of the headspace volatiles was hydrocarbon monoterpenes, which contribute slightly less than 80% of the total.

On-line coupling of fizzy extraction with gas chromatography.

Fizzy extraction (FE) is carried out by first dissolving a carrier gas (typically, carbon dioxide) in a liquid sample at a moderate pressure (typically, 150kPa) and then rapidly depressurizing the sample. The depressurization leads to instant release of numerous microbubbles in the liquid matrix. The abruptly released gas extracts the volatile solutes and elutes them toward a detector in a short period of time. Here, we describe on-line coupling of FE with gas chromatography (GC). The two platforms are highly compatible and could be combined following several modifications of the interface and adjustments of the extraction sequence. The analytes are released within a short period of time (1.5s). Thus, the chromatographic peaks are satisfactorily narrow. There is no need to trap the extracted analytes in a loop or on a sorbent, as it is done in standard headspace and microextraction methods. The approach requires only minor sample pretreatment. The main parameters of the FE-GC-mass spectrometry (MS) method were optimized. The results of FE were compared with those of headspace flushing (scavenging headspace vapors), and the enhancement factors were in the order of ~ 2 to 13 (for various analytes). The limits of detection for some of the tested analytes were lower in the proposed FE-GC-MS method than in FE combined with atmospheric pressure chemical ionization MS. The method was further tested in analyses of selected real samples (apple flavor milk, mixed fruit and vegetable juice drink, mango flavored drink, pineapple green tea, toothpaste, and yogurt). Graphical abstract.

Elucidation of headspace volatilome in Polianthes tuberosa flower for identifying non-invasive biomarkers

To date, no volatilome study has used the dynamic headspace method, based on adsorption–desorption principle, to investigate the chemical divergence of floral fragrance in Polianthes tuberosa L. (cv. Calcutta Single). This study proposes a suitable adsorbent/solvent combination to analyze emitted volatiles from this flower, allowing for a qualitative, and tentatively quantitative, floral volatilome using a holistic approach. Here, 13 different adsorbent/solvent combinations were used to determine the total emitted volatilome, from in situ and plucked flowers, using headspace and gas chromatography–mass spectrometry. Several adsorbent/solvent combinations were explored to optimize trapping the most diverse range of volatile organic compounds in a single attempt. A mixture of porous polymers (Porapak or Tenax) with graphite or charcoal were best when combined with dichloromethane as the eluting solvent. Among the two solvents, dichloromethane showed better desorption efficiency than hexane. For better elucidation of any specific chemical group, suitable adsorbent and solvent should be chosen properly or the quantity or quality of the volatilome captured would be compromised. Three distinct classes of volatile organic compounds were categorized: aromatics, terpenes, and fatty acid derivatives. Maximum diversity, along with quantity, was found with the aromatic group. Total chemical divergence of volatilome from in situ and freshly plucked flowers was similar. Benzyl salicylate, methyl 2-amino benzoate, germacrene D, farnesal, farnesyl acetate, and delta decalactone may be considered biomarkers for the origin of P. tuberosa floral scent.