Gas Chromotography Research Articles

Quantification of greenhouse gas emissions from managed biofuel plantations in a semi-arid landscape of Southern India

Jatropha curcas L. and Pongamia pinnata (L.) Pierre, are promising biofuel species in peninsular India. We quantified greenhouse gas fluxes from managed 9 year old plantations of these species for all seasons in three consecutive years (2012–2013, 2013–2014 and 2014–2015) using manually-operated closed chamber method. CH4, N2O and CO2 were analysed by using Varian 450-GC based on Gas Chromotography. The mean soil CO2, CH4, and N2O emissions in the Jatropha curcas plantation recorded were 7.720 t ha−1 y−1, 0.023 t ha−1 y−1 and 0.017 t ha−1 y−1, respectively. While in Pongamia pinnata soil CO2, CH4, and N2O emissions were recorded to be 7.633 t ha−1 y−1, 0.008 t ha−1 y−1 and 0.019 t ha−1 y−1, respectively. Our results indicate that Jatropha curcas has higher GHG emissions than Pongamia pinnata. A pronounced seasonal variability was observed in CH4, N2O and CO2 flux rates. The highest emissions for Jatropha curcas occur during rainy season, whereas for Pongamia pinnata it occurs during winter. Soil moisture and temperature being the most influencing factors for CO2 fluxes from soil. We conclude that these plantation has an effect on soil-atmosphere GHG exchanges and can act as a good source of mitigation of greenhouse gases.

Electrooxidation of coragen-contaminated wastewater using graphite electrodes and sorbent nano-hydroxyapatite

ABSTRACT The degradation of coragen (C18H14N5O2BrCl2) was tested by the electrooxidation process using graphite electrodes. Further, the advantage of nano-hydroxyapatite (n-Hap), as a cost-effective nano sorbent, in the removal of bromide from coragen was examined. Three different variables such as initial pH, electrolysis time and the current density were used to analyse the effects of the electrolytic process on the degradation of coragen. During electrolysis, under various stages, the parameters such as chemical oxygen demand (COD), chloride and bromide were analysed. The maximum COD, chloride and bromide removal efficiency of 96%, 50% and 99%, respectively, at pH 5, the maximum current density of 7.5 mA cm−2 and 120 min electrolysis time were achieved. Based on the final output of this study, it can be concluded that the electrolysis process can effectively reduce COD, chloride and bromide from coragen in an aqueous medium. Further, the degradation efficiency of the coragen was confirmed through different analyses such as UV spectra, Fourier transform infrared spectroscopy and gas chromotography–mass spectrometry analyses.

Observation of Diffusive Methane Emission from Holocene Mud Deposits on the Continental Shelf Offshore Southeastern Korea

Chun, J.-H.; Kim, Y.; Choi, J.-Y.; Kim, Y.J.; Lee, H.-J., and Kim, Y.H., 2020. Observation of diffusive methane emission from Holocene mud deposits on the continental shelf offshore southeastern Korea. In: Jung, H.-S.; Lee, S.; Ryu, J.-H., and Cui, T. (eds.), Advances in Geospatial Research of Coastal Environments. Journal of Coastal Research, Special Issue No. 102, pp. 127-136. Coconut Creek (Florida), ISSN 0749-0208.This study investigated gas-charged sediments found in Holocene mud deposits on the inner continental shelf offshore southeastern Korea. Headspace gases obtained from seven piston cores of Holocene mud deposits were analyzed using gas chromotography, and methane dissolved in the water column were analyzed using in situ methane sensors and gas chromotography. The methane concentration data from both sediments and water columns provide the evidences of diffusive methane emission from the inner continental shelf. The methane concentration of headspace gases ranged from 22.2 to 123.9 mM below the upper front of acoustic blanking zone (ABZ). The maximum anomaly of dissolved methane in the water column was 38.3 nM at a site 5 over rough seafloor in the ABZ, which is surrounded by water masses of relatively lower methane concentration. Dissolved methane concentrations were significantly lower (< 10 nM) in the upper water column (< 20 m water depth). Concentrations of dissolved methane within the whole water column in the gas-free zone (GFZ) were < 5 nM. These results imply that diffusive methane emission occurred from a rough seafloor with erosional features on the inner continental shelf at water depth of about 54 m; this diffusive methane emission was not related to high methane concentrations in piston core sediments of the shallow upper front of the ABZ.

Ultra- structure of Toombak; smokeless tobacco of Sudan and its effects on oral and systemic health

Introduction: Toombak is a smokeless tobacco used by the Sudanese. Nicotiana Rustica leaves are fermented, and sodium bicarbonate is added, increasing Ph. This causes high absorption spikes of unprotonated nicotine through mucosal epithelium, and into the blood, distinguishing Toombak as an addictive product. Furthermore,Toombak hashighmicrobial contamination due to its open field, rural production. Materials and methods: 21 tobacco samples were collected from 3 main towns in the capital Khartoum, Sudan. Analysis included microbiome (16S rRNA sequencing), metabolome (Liquid and Gas Chromotography- volatile organic compound method), heavy metal content and scanning electron microscopy (SEM). Results: Compared to limit of detection values (LOD), Tobacco specific nitrosamines (TSNA’s), in particular, 4(methylnitrosamino)-1-(3-pyridyl)–butanone (NNK) were markedly increased [NNK; 1.2-4.7 mg/g; LOD 0.02]. Free nicotine ranged from 16-31 mg/g; [LOD 0.01]. High choline and carnitine, volatile aldehydes; and benzyl alcohol were also detected. 8 cations, of which iron [1465 mg/kg] and copper [3.76 mg/kg] were strikingly observed, compared to average levels from other products; [Iron 20-60mg/kg, Copper 1.3mg/kg]. 8 Phyla, including but not limited to; Actinobacteria; cornyebacterium(contain nitrate reductase genes) and Firmicutes; staphylococcus and facklamia, were sequenced. SEM highlighted a non-homogenous product with elevated sodium spectrum. Conclusions: TSNA’s were potent in Toombak due to high starting nicotine and rich nitrate reductase bacteria. High choline and carnitine can promote cardiovascular disease through their conversion to trimethylamine-N-oxide. Diphtheria and infective endocarditis are associated with cornyebacterium and facklamia respectively while staphylococcus can lead to numerous systemic opportunistic diseases.

Gas Chromatography-Mass Spectrometry (GC-MS) Analysis of Antibiotic producing Actinomycetes Soils samples

In this study,a total of 120 agriculture soils samples,theirty two Actinomycetes isolates were isolated from ten different locations in Babylon city which were purified several times on International Streptomyces project-2 agar medium (ISP-2). All these isolates were tested for antibacterial activity by primary and secondary screening test against gram positive pathogenic bacteria (Staphylococcus albus,Staphylococcus aureus,and Streptococcus pyogenes) and gram negative pathogenic bacteria (Klebsillae pnemoniae,Escherichia coli,Pseudomonas aerouginosa,Seratia marcescens and Aeromonas hydrophila), televe isolates were showed antibacterial activity against these bacteria. Bacterial extraction of three of actinomycetes isolates which showed high antibacterial activity,the isolates (No.3:MS.A.21,No.8:AG.A.72,No.10:R.A.98) were chemicly characterized by gas chromotography techniques (GC-Mass) to detect volatile organic compounds.Five components were identified in the ethyl acetate bacteria extract. The compounds were Acetic acid (58.42%) as the major component followed by 2-Butanone,3-hydroxy (21.23%),Butanoic acid,2-methyl (8.76%),2, 3-Butanediol, [R- (R*, R*)] (7.75%) and last couponed propanoic acid, 2-methyl (3.84%) respectively. Figure (4-1) shows the mass spectrum and structures of the identified components.

Chemopreventive glucosinolate accumulation in various broccoli and collard tissues: Microfluidic-based targeted transcriptomics for by-product valorization.

Floret, leaf, and root tissues were harvested from broccoli and collard cultivars and extracted to determine their glucosinolate and hydrolysis product profiles using high performance liquid chromatography and gas chromotography. Quinone reductase inducing bioactivity, an estimate of anti-cancer chemopreventive potential, of the extracts was measured using a hepa1c1c7 murine cell line. Extracts from root tissues were significantly different from other tissues and contained high levels of gluconasturtiin and glucoerucin. Targeted gene expression analysis on glucosinolate biosynthesis revealed that broccoli root tissue has elevated gene expression of AOP2 and low expression of FMOGS-OX homologs, essentially the opposite of what was observed in broccoli florets, which accumulated high levels of glucoraphanin. Broccoli floret tissue has significantly higher nitrile formation (%) and epithionitrile specifier protein gene expression than other tissues. This study provides basic information of the glucosinolate metabolome and transcriptome for various tissues of Brassica oleracea that maybe utilized as potential byproducts for the nutraceutical market.

Near-Infrared Spectroscopy Using a Supercontinuum Laser: Application to Long Wavelength Transmission Spectra of Barley Endosperm and Oil.

The supercontinuum laser is a new type of light source, which combines the collimation and intensity of a laser with the broad spectral region of a lamp. Using such a source therefore makes it possible to focus the light onto small sample areas without losing intensity and thus facilitate either rapid or high-intensity measurements. Single seed transmission analysis in the long wavelength (LW) near-infrared (NIR) region is one area that might benefit from a brighter light source such as the supercontinuum laser. This study is aimed at building an experimental spectrometer consisting of a supercontinuum laser source and a dispersive monochromator in order to investigate its capability to measure the barley endosperm using transmission experiments in the LW NIR region. So far, barley and wheat seeds have only been studied using NIR transmission in the short wavelength region up to 1100 nm. However, the region in the range of 2260-2380 nm has previously shown to be particularly useful in differentiating barley phenotypes using NIR spectroscopy in reflectance mode. In the present study, 350 seeds (consisting of 70 seeds from each of five barley genotypes) in 1 mm slices were measured by NIR transmission in the range of 2235-2381 nm and oils from the same five barley genotypes were measured in a cuvette with a 1 mm path length in the range of 2003-2497 nm. The spectra of the barley seeds could be classified according to genotypes by principal component analysis; and spectral covariances with reference analysis of moisture, β-glucan, starch, protein and lipid were established. The spectral variations of the barley oils were compared to the fatty acid compositions as measured using gas chromotography-mass spectrometry (GC-MS).

One-step separation of terpenoids from leaves extracts of Solanum cernuum by high-performance countercurrent chromatography

ABSTRACTSolanum cernuum is a native shrub from Brazil that has been used as medicine since the nineteenth century. Although it has been utilized for a long time, there are few studies regarding its chemical composition and it motivated us to investigate this species. The dried leaves of S. cernuum were extracted with methanol and the obtained extract was further partitioned with different organic solvents. As part of our investigation, the n-hexane fraction was submitted to CCC with a nonaqueous solvent system composed of hexane, acetonitrile, and ethyl acetate (5:5:1, v/v/v). Three terpenoids were obtained by one-step separation and identified as 24-oxo-31-norcycloartanone (22.8 mg), lupeol (9.4 mg), and cycloeucalenone (13.4 mg). Complementarily, the solvents system used on the separation have had their compositions determined by gas chromotography–flame ionization detector (GC-FID).

Some Physico-Chemical Properties of Edible and Forage Watermelon Seeds

The crude oil, crude protein, crude ash, crude fiber, total phenol and antioxidant activity values, peroxide values, specific gravity, the refraxtive index and acid value of Citrullus lanatus and their oils were determined. Fatty acid composition of seeds belong to both watermelon were determined by Gas Chromotography (GC). These oils are important sources of essential fatty acid, linoleic acid (63.19% to 72.03%). Oleic acid contents of seeds ranged between 17.55% (Forage watermelon kernel) to 24.65% (watermelon kernel). Cd, Cr, Mn contents of watermelon kernel were found between 0.02 to 0.09 mg/kg, 0.37 to 1.46 mg/kg and 6.08 to 11.31 mg/kg, respectively. Ca, K, Mg, Na, P and S were found as major elements in seed samples. Total phenol contents of watermelon seeds ranged between 0.13 mg GAE /100 mg to 0.30 mg GAE/100 mg. Antioxidant activity of Citrullus lanatus (Thunb.) seeds (5.06 and 13.90%) were found higher than those of normal seeds (1.31 and 4.42%). Peroxide values of watermelon oils ranged between 7.6 meqO 2/kg to 11.7 meqO 2/kg.

Biodiesel Production from a Novel Raw Material Tung Oil

Tung oil from the south of Shaanxi province was assayed by chemical analysis technology, its compositions of fatty acid was discovered with gas chromotography. As experiment results, Lipase-catalyzed Tung oil producing biodiesel plays a dominant role in the process of enzymatic synthesis of biodiesel in tert-butanol reaction system.we needed controlling the continuous flow rate in the reaction system and maintained a very high FAMEs yield. Tung oil from south Shaanxi could be an ideal raw material for biodiesel production.

Biochemical activities of iranian Cymbopogon olivieri (Boiss) Bor. essential oil

Cymbopogon olivieri essential oil from aerial parts was analyzed by gas chromotography and gas chromatography-mass spectrometry and led to the identification of 38 compounds. Piperitone (72.8%), 4-carene (11.8%) and β-himachalene (7.6%) were found as the major components of the oil. The antimicrobial activity was achieved using disc-diffusion and microbroth dilution assays and microbicidal kinetics of oil was screened against different microorganisms. The possible antioxidant activity of oil was evaluated by diphenylpicrylhydrazyl free-radical scavenging system. The oil had excellent antimicrobial activity against Bacillus cereus, Staphylococcus epidermidis and Streptococcus pneumoniae. The oil exhibited inhibitory effect against Bacillus subtilis and fungi. Dvalues of oil were 12.5, 10 and 2.4 min for Escherichia coli, Staphylococcus aureus and Candida albicans, respectively. The IC50 value of Cymbopogon olivieri oil was 35 mg/ml and its antioxidant activity was lower than that of butylated hydroxytoluene. Cymbopogon olivieri oil possesses compounds with antimicrobial properties that can be used as antimicrobial agents.

Comparison of gas chromotography, spectrophotometry and near infrared spectroscopy to quantify prussic acid potential in forages

Sorghum [Sorghum bicolor (L.) Moench] has been shown to contain the cyanogenic glycoside dhurrin, which is responsible for the disorder known as prussic acid poisoning in livestock. The current standard method for estimating hydrogen cyanide (HCN) uses spectrophotometry to measure the aglycone, p-hydroxybenzaldehyde (p-HB), after hydrolysis. Errors may occur due to the inability of this method to solely estimate the absorbance of p-HB at a given wavelength. The objective of this study was to compare the use of gas chromatography (GC) and near infrared spectroscopy (NIRS) methods, along with a spectrophotometry method to estimate the potential for prussic acid (HCNp) of sorghum and sudangrasses over three stages maturities. It was shown that the GC produced higher HCNp estimates than the spectrophotometer for the grain sorghums, but lower concentrations for the sudangrass. Based on what is known about the analytical process of each method, the GC data is likely closer to the true HCNp concentrations of the forages. Both the GC and spectrophotometry methods yielded robust equations with the NIRS method; however, using GC as the calibration method resulted in more accurate and repeatable estimates. The HCNp values obtained from using the GC quantification method are believed to be closer to the actual values of the forage, and that use of this method will provide a more accurate and easily automated means of quantifying prussic acid.

Chemical and fatty acid composition of Cyperus esculentus

The physical and chemical properties of chufa tubers are given in Table 1. The nuts were found to be rich in oil (21.57%), fiber (22.13%), and protein (8.11%). Previous studied reported 932.8 g/kg dry matter, 245 g/kg crude lipid, 256.8 g/kg starch, 14.3 g/kg ash, 50.5 g/kg protein, 89.1 g/kg crude fibre, and 154.3 g/kg total sugar [3]. The fatty acid composition of chufa tuber was determined by gas chromotography (Table 2). Oleic acid (72.7%) was present in the highest concentration, followed by palmitic (14.8%), linoleic (11.4%), arachidic (0.6%), and linolenic (0.5%) acids. The fatty acid composition of chufa oil comprised 689.2–732.9 g/kg oleic acid, 125.5–141.2 g/kg palmitic acid, and 99.6–154.6 g/kg linoleic acids [3]. The mineral contents of chufa tuber were determined by ICP-AES (Table 3). Chufa tubers were found to be rich in some minerals such as Al (709.1 mg/kg), Ca (739.1 mg/kg), Fe (412.5 mg/kg), K (9821.7 mg/kg), Mg (1190.5 mg/kg), Na (2407.4 mg/kg), and P (3012.6 mg/kg). Caglarirmak reported 280–380 mg/100 g P, 230–340 mg/100 g K, 81–99 mg/100 g Mg, and 67–105.5 mg/100 g Ca in fresh walnut kernels [10]. This work attempts to contribute to knowledge of the nutritional properties of these tubers. The physical-chemical properties and fatty acid composition were analyzed according to AOAC [11]. The methyl esters of the fatty acids (1 L) were analyzed in a gas chromotograph (Shimadzu GC-2010) equipped with a flame ionization detector (FID) and a fused silica capillary column (60 m 0.25 mm i.d.; film thickness 0.20 m).

Characterization of Bulgarian oil shale kerogen revealed by oxidative degradation

A 13-step alkaline permanganate degradation of Bulgarian oil shale kerogen concentrate at ambient temperature was carried out. A high yield of oxidation products (90.1%) and a low yield of gaseous products (2.79%) were obtained. IR and 1H NMR spectroscopic studies have shown that two significantly different types of high molecular products are present in kerogen. Further oxidation of these structures leads to the formation of low molecular aliphatic and aromatic acids, proven by gas chromotography (GC) and gas chromatography-mass spectrometry (GC-MS). The data obtained at these mild conditions allow us to acquire detailed information about the aromatic structures and polymethylene chain lengths in kerogen. The 5-step oxidation of the kerogen at 90 °C provides information about stable aromatic structures. Soluble and insoluble polyfunctional acids in acid medium have close molecular masses and spectral characteristics. The amount of benzene and naphthalene carboxylic acids is 11.3% of the organic matter of the oil shale.

Development of a DC-plasma torch constructed with graphite electrodes and an integrated nebulization system for decomposition of CCl4

This work describes the development of a continuous flow plasma torch with graphite electrodes and an integrated nebulization system for the elimination of organochlorine liquid waste (carbon tetrachloride) on a small scale. The gases resulting from the pyrolysis of the carbon tetrachloride by the plasma were collected and identified by gas chromatography, coupled with mass spectrometry (GC-MS). Monitoring was carried out by gas chromotography with flame ionization detection (GC-FID). It was observed that the thermal plasma technique eliminated the carbon tetrachloride completely, being characterized by low cost, operational simplicity and reduced dimensions. This technique presents a suitable environmentally correct alternative, since it reduces the total emission of organochlorine gases.

O-Acetylserine and the Regulation of Expression of Genes Encoding Components for Sulfate Uptake and Assimilation in Potato

cDNAs encoding a high-affinity sulfate transporter and an adenosine 5'-phosphosulfate reductase from potato (Solanum tuberosum L. cv Desiree) have been cloned and used to examine the hypothesis that sulfate uptake and assimilation is transcriptionally regulated and that this is mediated via intracellular O-acetylserine (OAS) pools. Gas chromotography coupled to mass spectrometry was used to quantify OAS and its derivative, N-acetylserine. Treatment with external OAS increased sulfate transporter and adenosine 5'-phosphosulfate reductase gene expression consistent with a model of transcriptional induction by OAS. To investigate this further, the Escherichia coli gene cysE (serine acetyltransferase EC 2.3.1.30), which synthesizes OAS, has been expressed in potato to modify internal metabolite pools. Transgenic lines, with increased cysteine and glutathione pools, particularly in the leaves, had increased sulfate transporter expression in the roots. However, the small increases in the OAS pools were not supportive of the hypothesis that this molecule is the signal of sulfur (S) nutritional status. In addition, although during S starvation the content of S-containing compounds decreased (consistent with derepression as a mechanism of regulation), OAS pools increased only following extended starvation, probably as a consequence of the S starvation. Taken together, expression of these genes may be induced by a demand-driven model, via a signal from the shoots, which is not OAS. Rather, the signal may be the depletion of intermediates of the sulfate assimilation pathway, such as sulfide, in the roots. Finally, sulfate transporter activity did not increase in parallel with transcript and protein abundance, indicating additional posttranslational regulatory mechanisms.

Polar lipid biomarkers of free-living bacteria from oligotrophic marine waters

Free-living marine bacteria isolated from oligotrophic Mediterranean waters were enriched in culture to characterize their phospholipid fatty acids (PLFAs). Odd chain iso- and anteiso-FAMEs and n−16:0 were the predominant structural PLFAs, together with a homologous series identified as mid-chain methoxy FAMEs. The dominant methoxy fatty acids identified were 9-CH3O-15:0, 9-CH3-16:0 and 11-CH3O-17:0, occuring as pairs of stereoimers. Methoxy fatty acids accounted for up to 37% of PLFAs of free-living bacteria, which sets them as promising new biomarkers for bacteria of oligotrophic waters. Although similar homologues have already been characterized in a variety of eukaryotes and prokaryotes, methoxy fatty acids are identified here for the first time in marine bacteria. Analytical difficulties that may hinder the characterization of these biomarkers are presented, and structural elucidation keys by gas chromotography coupled to mass spectrometry are discussed. Whilst bacterial branched fatty acids were transferred to storage lipids of bacterivorous flagellates methoxy acids were not transferred to higher trophic levels in the studied conditions.

Characteristics of heat treated polyparaphenylene for lithium-ion secondary batteries

In order to clarify the mechanism of Li-ions insertion/deinsertion into/from polyparaphenylene (PPP)-based carbons, the PPP carbonization has been analyzed. The weight loss of the PPP carbonized samples increased at a faster rate in the temperature range 600–680 °C. Hydrocarbons such as benzene and biphenyl were mainly detected by gas chromotography–mass spectrometry at a temperature of 710 °C during thermo-gravimetric analysis of PPP. The microtexture and the structure of heat treated PPP samples were characterized by high resolution transmission electron microscopy and investigated by image processing. The resistivity measurements of heat treated PPP showed a drastic decrease in the 680–730 °C HTT range. We related the microtexture evolution, the hydrocarbons release and the resistivity decrease of PPP carbonized samples to Li-ion battery capacity.

Class- and Structure-Specific Separation, Analysis, and Identification Techniques for the Characterization of the Sulfur Components of JP-8 Aviation Fuel

Methods have been described for separating the sulfur content of aviation fuels into chemical classes for identification and quantitation. These separation methods simplified the fuel matrix, which allowed non-element-specific detection methods, such as mass spectrometry (MS), to be used for sulfur detection. These matrix simplification methods also enhanced the ability of element-specific detection methods, such as atomic emission detection (AED), to identify sulfur species that are present in the fuel. Separation of a model fuel mixture, as well as several representative aviation fuels, was performed using several different methods, including class-specific chemical oxidation methods that used iodine and another that used hydrogen peroxide, and a polarity-based separation that used a polar high-pressure liquid chromatography (HPLC) column. Following separation, sulfur concentration was quantified into “reactive” and “nonreactive” classes, on the basis of the ease of transformation of the species, using chemical oxidation procedures, which also relates to the tendency for the species to undergo typical hydrodesulfurization reactions with hydrogen. These two classes were broken down further, with sulfur compounds being classified as thiol, sulfides and disulfides, thiophenes, benzothiophenes, or dibenzothiophenes. The separation and identification methods proved to be robust and transferable; the results from two independent laboratories were in good agreement. Sulfur in the jet fuels tested in this study appeared mainly as thiols, sulfides, and disulfides, as determined by gas chromotography−atomic emission detection (GC−AED), following the chemical oxidation procedures. Of the refractory sulfur compounds, benzothiophenes comprised the majority, as determined by GC−MS following the (HPLC) fractionations. Thiophenes and dibenzothiophenes contributed minor amounts to the total concentration of refractory sulfur compounds. Two main components of the benzothiophene class were identified to be 2,3-dimethyl benzothiophene and 2,3,7-trimethyl benzothiophene.

Cuticular wax alkanes and alcohols used as markers to estimate diet composition of sheep ( Ovis aries)

The chemical components in plant cuticular wax can be used as markers to estimate the species composition of the diet of grazing animals. In this experiment, sheep ( Ovis aries) grazed swards consisting of two sown species of Lotus ( L. corniculatus and L. pedunculatus), two sown grasses ( Phalaris aquatica and Austrodanthonia richardsonii) and volunteer annual grasses and legumes (dominated by Vulpia myuros and Trifolium spp.). The botanical composition of the sward was estimated before and after grazing over three days by four sheep. During the grazing period, samples of whole plants of the species present, plus rectal faecal samples from the sheep, were collected, freeze-dried and ground prior to the extraction of cuticular wax n-alkanes and long-chain alcohols. Purified alkanes and alcohols in samples of faeces and plants were quantified by gas chromotography. The species composition of the sheep diets was estimated by relating faecal alkane and alcohol contents to those of the plant species on offer, using the ‘EatWhat’ software package. Principal Components Analysis explained 75% of the variance in the pattern of alkane concentrations between the species on the first two axes. PCA using alcohols accounted for 68% of the variance on the first two axes and separated the Lotus species from the grasses and clovers. Comparison of the two PCA, using Orthogonal Procrustes Rotation, indicated that the long-chain alcohols contributed extra information over and above that provided by the alkanes. Discriminant analysis of alkane and alcohol concentrations enabled a clear separation of Lotus, clover and grass species groups. Using alkanes as markers, the diet consumed by sheep contained 18±1.1% Lotus, whilst using both alkanes and alcohols, the estimated Lotus content of the diet (26±1.2%) was closer to the Lotus content of the sward (31%). Diet composition estimates indicated that the Lotus component consisted mostly (>90%) of L. corniculatus. This apparent selection against L. pedunculatus may relate to the much higher condensed tannin content in that species.