Dunaliella salina microalga pressurized liquid extracts as potential antimicrobials

In the present work, the antimicrobial activity of different pressurized liquid extracts obtained from Dunaliella salina microalga was tested against several microorganisms of importance for the food industry (Escherichia coli, Staphylococcus aureus, Candida albicans, and Aspergillus niger). Different solvents (hexane, petroleum ether, hexane, and water) and extraction conditions (40, 100, and 160 degrees C) were tested. Results showed that the best antimicrobial activity was obtained for each solvent at the highest extraction temperature (160 degrees C). Likewise, the extraction yield followed the same trend, i.e., increasing with extraction temperature and was at a maximum when ethanol was used as an extraction solvent. Water extracts had the lowest extraction yields. In general, the best results in terms of antimicrobial activity were obtained using petroleum ether and hexane, although ethanolic extracts also showed good antimicrobial activity. Because the main antimicrobial activity of the extracts was against bacteria, the extracts can be considered to be specifically antibacterial. The extracts were analyzed by gas chromatography-mass spectrometry in order to identify the compounds responsible for activity. Fifteen different volatile compounds as well as several fatty acids (mainly palmitic, alpha-linolenic, and oleic acids) that could have been responsible for the antimicrobial activity were identified in the extracts. beta-Cyclocitral, alpha- and beta-ionone, neophytadiene, and phytol were identified among other volatile compounds; all of these compounds have previously been described as antimicrobial agents.     

Green processes based on the extraction with pressurized fluids to obtain potent antimicrobials from Haematococcus pluvialis microalgae

In the present work, the antimicrobial activity of different pressurized liquid extracts obtained from Haematococcus pluvialis microalga was tested against several microorganisms of importance for the food industry (Escherichia coli, Staphylococcus aureus, Candida albicans and Aspergillus niger). Extractions were performed with hexane and ethanol at four different temperatures (50, 100, 150 and 200 °C) for 20 min. The results showed that extracts obtained with both solvents (hexane and ethanol) from the green motile cells of the microalgae (green phase) presented a low antimicrobial activity against all the microorganisms tested. However, the antimicrobial activity of the extracts obtained from the red hematocysts without flagella (red phase) was totally different depending on the solvent used for the extraction. Hexane extracts showed an antimicrobial activity quite similar to that obtained with the green microalgae, while the antimicrobial activity of ethanol extracts was much higher. This fact seems to indicate that compounds related to antimicrobial activity of this microalga are found in higher quantities in the red phase of the microalgae and could be relatively polar compounds. Moreover, ethanol extracts from the red phase obtained at 100 °C presented the highest antimicrobial activity. In order to identify the compounds responsible for the antimicrobial activity, a GC-MS characterization of the extracts obtained with both hexane and ethanol at 100 °C, for Haematococcus pluvialis in the green and red phases was also performed. Therefore, the highest antimicrobial activity of the ethanol extract corresponding to red Haematococcus can be associated with the presence in this extract of short-chain fatty acids, which have been previously described to possess antimicrobial activity.     

Supercritical carbon dioxide extraction of compounds with antimicrobial activity from Origanum vulgare L.: determination of optimal extraction parameters

Oregano leaves were extracted using a pilot-scale supercritical fluid extraction plant under a wide range of extraction conditions, with the goal of determining the extraction and fractionation conditions to obtain extracts with optimal antimicrobial activity. In this investigation, the essential oil-rich fractions were selectively precipitated in the second separator, and their chemical composition and antimicrobial activity were investigated. Gas chromatography-mass spectrometry analysis of the various fractions resulted in the identification of 27 compounds of the essential oil. The main components of these fractions were carvacrol, trans-sabinene hydrate, cis-piperitol, borneol, terpinen-4-ol, and linalool. Antimicrobial activity was investigated by the disk diffusion and broth dilution methods against six different microbial species, including two gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), two gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), a yeast (Candida albicans), and a fungus (Aspergillus niger). All of the supercritical fluid extraction fractions obtained showed antimicrobial activity against all of the microorganisms tested, although the most active fraction was the one obtained in experiment 5 (fraction was obtained with 7% ethanol at 150 bar and 40 degrees C). C. albicans was the most sensitive microorganism to the oregano extracts, whereas the least susceptible was A. niger. Carvacrol, sabinene hydrate, borneol, and linalool standards also showed antimicrobial activity against all of the microorganisms tested, with carvacrol being the most effective. Consequently, it was confirmed that essential oil from experiment 5, with the best antimicrobial activity, also presented the highest quantity of carvacrol.     

Modulation of antioxidant,chelating and antimicrobial activity of poplar chemo-type propolis by extraction procures

This investigation was aimed to prepare solid propolis extracts by lyophilisation and to evaluate the efficiency of different extraction procedures (maceration/ultrasound extraction) and different types of extraction media used on extraction of phenolic compounds (TP), flavonoids (TF) and phenolic acids (TPA) from the raw poplar type propolis. Obtained lyophilised extracts were evaluated in terms of extraction yield, antioxidant potential and antimicrobial activity against selected bacterial/fungal stains. Those parameters varied significantly as a function of extraction parameters applied. In this regard, 80% ethanol was found to be the preferred extraction medium, allowing efficient extraction of TP and TF with high extraction yields. The resulting extracts were notable radical scavengers showing high antibacterial efficiency against Streptococcus mutans but were less efficient against Pseudomonas aeruginosa. Also, moderate antifungal activity against Candida albicans was observed. On the contrary, extracts prepared by aqueous extraction showed poor antimicrobial activity against tested stains but were active Fe²⁺ chelators. Ultrasound extraction showed comparable efficiency as maceration in extraction of bioactive compounds from the raw propolis, but offered additional advantages by ensuring the efficient extraction of phenolic compounds from propolis at rather low temperature (4 °C vs. 25/50 °C for maceration) in a short time (30 min vs. 24 h for maceration).     

Functional characterization of pressurized liquid extracts of Spirulina platensis

Three different parameters (temperature, solvent, and extraction time) were studied regarding to pressure liquid extraction (PLE) of antioxidant and antimicrobial compounds from Spirulina platensis. Two different antioxidant methods, β-carotene bleaching method and DPPH^• (2,2-Diphenyl-1-picrylhydrazyl hydrate) free radical scavenging assay, were used to determine the optimal PLE conditions for antioxidants extraction. The selected conditions were as follows: extraction temperature equal to 115 °C, extraction time equal to 15 min and ethanol as extracting solvent. The main antioxidant compounds found in this extract were identified as zeaxanthin, a myxoxanthophyll-like compound and very polar phenolic compounds. Moreover, antimicrobial activity of different PLE fractions was tested against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 11775, Candida albicans ATCC 60193, and Aspergillus niger ATCC 16404. Data obtained showed the hexane and petroleum ether extracts were slightly more active than ethanolic extracts. As for water extracts, none of them were active against the microorganisms tested. Data indicated that both 115 and 170 °C were the best extraction temperatures conditions in order to optimize the extraction of antimicrobial compounds, whereas 9 min was the optimal extraction time. Besides, C. albicans was the most sensitive microorganism to all Spirulina PLE extracts.     

Comprehensive characterization of the functional activities of pressurized liquid and ultrasound-assisted extracts from Chlorella vulgaris

Chlorella vulgaris has been referred as a potential source of bioactive compounds (carotenoids and fatty acids). In this work, the ability of an environmentally friendly extraction technique such as Pressurized Liquid Extraction (PLE) and a traditional extraction technique such as Ultrasound-Assisted Extraction (UAE) to obtain functional compounds from C. vulgaris, at analytical scale, has been demonstrated. Seeked bioactivities were antioxidant and antimicrobial, for their interest in the food industry. Therefore, a methodology including analytical extraction, in-vitro assays and chemical characterization via HPLC-DAD and GC–MS has been used to determine the interest of Chlorella as a source of functional food ingredients. Results demonstrated that PLE provide higher yields than UAE while similar bioactivities were obtained. Important concentration of carotenoids (lutein, neoxanthin, β-carotene, etc.), chlorophylls, sterols, phytols, and fatty acids (among others) have been found in Chlorella extracts that could be correlated to the observed biological activity.     

Design of volatile organic compounds profiles of roasted Coffea arabica extracts produced by supercritical and conventional solvents

This work addresses the potential of supercritical fluid extraction (SFE) to design volatile organic compounds (VOCs) profiles using roasted Coffea arabica. On the whole, 57 VOCs were identified by HS-SPME/GC–MS. A full factorial design was adopted to study the effect of pressure (180 and 300 bar), temperature (40 and 80 °C) and ethanol content (0 and 5 wt.%). The total extraction yield ranged from 1.4 wt.% to 9.8 wt.%. At 180 bar and 80 °C, two extracts exhibited VOCs amount up to 3.5 times higher than the dichloromethane extract. Temperature and pressure favoured VOCs amount and total yield in conflicting ways, and ethanol had a negligible effect on VOCs amount. At 180 bar and 80 °C, the VOCs profile revealed a reinforcement of pyrroles, phenols, cyclopentenes and pyrans, at the expense of pyridines, carboxylic acids and furans. Hence, this essay evidences the potential of SFE to engineer coffee VOCs profiles.     

LIPIDS OF WHEAT, CORN AND POTATO STARCH

The lipid constituents from wheat, corn and potato starches were analyzed, as was the composition of nonstarch compounds present in these lipid extracts. The lipids were extracted from starch granules using n- propanol-water (3:1, v/v) via cold and hot extraction into surface and internal lipid fractions, respectively; fatty acid profiles of the fractions so obtained were then carried out. The content of surface lipids was greatest from potato and wheat starches, whereas cornstarch was characterized as having the highest relative percentage of internal lipids. Hot extraction resulted in an increase in the lipid content for all extracts, and of the starches investigated, the lipids from cornstarch contained the highest percentage of polyunsaturated fatty acids. Unlike that of wheat starch, it was noted that the fatty acid, C20: 1 (n-9), could only be extracted from corn and potato starch granules by the hot extraction technique. Lysophosphatidylcholine (LPC) and some phenolics were found to bind to wheat starch granules, but not to those of corn and potato. Using HPLC-UV-DAD analysis, five phenolic compounds were detected in the lipids extracted from wheat starch by hot extraction. Maxima from UV-DAD spectra of the compounds were observed at a wavelength of 337.4 or 332.7 nm, and are characteristic of phenolic acids or their derivatives.     

三种微藻油脂肪酸组成和理化性质分析

对3种海水微藻油含量、脂肪酸组成和油脂的理化性质进行分析。结果表明:盐藻油、螺旋藻油和小球藻油含量分别为17.69%、6.36%和11.64%,棕榈酸、油酸、亚油酸和亚麻酸是杜氏盐藻油和小球藻油的主要脂肪酸组分,而螺旋藻油主要含有棕榈酸、亚油酸和γ-亚麻酸;盐藻、螺旋藻和小球藻油均具有较高的C/H值,3种盐藻油的C/H值分别为7.35、7.32和7.58;3种微藻油酸值分别为盐藻油12.64mg KOH/g、螺旋藻油17.65mg KOH/g和小球藻油9.8mg KOH/g;热值分别为盐藻油36.07MJ/kg、螺旋藻油37.01MJ/kg和小球藻油35.00MJ/kg;3种微藻油酸值和黏度均较高,流动性较差。     

Use of supercritical CO<Subscript>2</Subscript> to obtain extracts with antimicrobial activity from <Emphasis Type="Italic">Chaetoceros muelleri</Emphasis> microalga. A correlation with their lipidic content

Supercritical CO₂ extracts of the marine diatom Chaetoceros muelleri (gracilis) have been investigated for their potential use as food preservatives, namely, as antimicrobials. A screening of different pressures and temperatures for supercritical CO₂ extraction was assayed in order to determine the main factors controlling the yield and antimicrobial activity of the extracts. Since the potential antimicrobial activity of these CO₂ extracts is mainly induced by the lipidic fraction, HPLC with evaporative light scattering detection (HPLC-ELSD) and GC with flame ionization detection (GC-FID) were used to identify lipid families and fatty acids, respectively. Antimicrobial activity of the extracts was measured against Staphyloccocus aureus, Escherichia coli and Candida albicans. Possible correlations between antimicrobial activity of extracts and their chemical composition were investigated, concluding that the total triglycerides and the DPA content seem to be the main parameters controlling the antimicrobial activity of the studied extracts.     

Comparison of simultaneous distillation extraction (SDE) and solid‐phase microextraction (SPME) for the analysis of volatile compounds in dry‐cured ham

Simultaneous distillation extraction (SDE) and solid‐phase microextraction (SPME) using a carboxen/polydimethylsiloxane fibre were compared for their effectiveness in the extraction of volatile compounds from dry‐cured ham samples. A higher number of compounds was detected using SPME owing to the use of a solvent delay time in the GC‐MS analysis of SDE extracts. SPME was more efficient in extracting low molecular weight and high volatility compounds, while SDE was able to extract compounds with low volatilities that were not extracted using SPME. Both techniques satisfactorily extracted most volatiles previously highlighted as odour‐active compounds in dry‐cured ham. However, the ratio between some compounds from lipid oxidation and those from degradation of amino acids was much lower in SDE extracts than with SPME, which could be a consequence of the development of Strecker degradation of amino acids during distillation in SDE owing to the high temperatures used. Similarly, diunsaturated aldehydes detected in SDE extracts were absent using SPME, probably owing to oxidation of polyunsaturated fatty acids in SDE as a consequence of the temperature during extraction. Copyright © 2004 Society of Chemical Industry     

Supercritical fluid fractionation of fatty acid ethyl esters from butteroil

Countercurrent supercritical fractionation of the fatty acid ethyl esters from butteroil has been investigated. The main objective of the present study was to obtain extracts rich in short- and medium-chain fatty acid ethyl esters. To that end, transesterification of the original butteroil was used to transform the triacylglycerols into the corresponding fatty acid ethyl esters. Then, several supercritical fluid extractions were carried out at pressures ranging from 8.9 to 18.6 MPa and at 2 different temperatures (48 and 60°C). The flow ratio of CO₂ to butteroil was 15. Composition and yield of short- and medium-chain fatty acid ethyl esters was evaluated at different extraction conditions. Extracts containing ∼70% short- and medium-chain fatty acid ethyl esters were obtained at 101 bar and 60°C, and can be used as starting material for the production of highly valuable functional lipids.     

Extraction and separation of volatile and fixed oils from seeds of Myristica fragrans by supercritical CO₂: chemical composition and cytotoxic activity on Caco-2 cancer cells

Isolation of volatile and fixed oils from nutmeg have been obtained by supercritical fractioned extraction with carbon dioxide. Extraction experiments were carried out at pressures of 90 and 250 bar and temperature of 40 °C. The extraction step performed at 90 bar produced a volatile fraction mainly formed by myristicin (32.8%), sabinene (16.1%), α-pinene (9.8%), β-pinene (9.4%), β-phellandrene (4.9%), safrole (4.1%) and terpinen-4-ol (3.6%). The oil yield relative to this step of the process was 1.4% by weight of the charge. The last extraction step at 250 bar produced a butter-like material (nutmeg butter). The yield of this step was 14.4% by weight. The most represented fatty acids of fixed oil from nutmeg were 14:0 (79.2%), 18:1 n-9 (7.4%) and 16:0 (6.1%), and in particular the unsaturated fatty acids 18:1 n-9 averaged 32.96 μg/mg of oil. The level of myristicin in the nutmeg essential and fixed oils was also directly quantified by reversed HPLC-DAD. Moreover, the essential oil obtained from nutmeg, as well as myristicin, showed a significant in vitro inhibitory effect on the growth of a colon cancer cell line (undifferentiated Caco-2 cells). PRACTICAL APPLICATION: In this study, the chemical characterization and the anticancer activity of nutmeg oils obtained by supercritical extraction with carbon dioxide were investigated. This is important for their potential application in food and pharmaceutical industries.     

Effect of pulsed electric fields – assisted extraction on anti-inflammatory and cytotoxic activity of brown rice bioactive compounds

The bioactive compounds of brown rice exhibit many beneficial health effects, ranging from antioxidant to cytotoxic activities. Pulsed Electric Field (PEF) pretreatment can significantly enhance their extraction, through the induction of the electro-permeabilization of the cell membranes.This paper aims to demonstrate that PEF-assisted extraction of brown rice enables not only enhanced yields of antioxidant compounds, such as γ-oryzanol, polyphenols and phenolic acids, and of saturated and unsaturated fatty acids, but also increased cytotoxic effects on cancer cells.Initially, the PEF-assisted extraction conditions have been defined by the assessment of the cell permeabilization index via impedance measurements and the DPPH antioxidant activity. Subsequently, the biological effects of PEF have been evaluated on the cytotoxicity and anti-inflammatory properties against human colon cancer cell line HT29.The results show that PEF-assisted extraction, enhancing the yield of bioactive compounds, with respect to untreated extracts, significantly promotes their antioxidant activity, which is correlated with an increased HT29 cells cytotoxicity. In addition, PEF extracts of brown rice substantially inhibit also gene expression and interleukin production in colon cancer cells, suggesting their exploitation as natural anti-inflammatory agents.The integration of PEF pretreatment in the solvent extraction process of bioactives from brown rice appears, therefore, as a promising practice to significantly enhance their biological activity.     

Identification of ground beef-derived fatty acid inhibitors of autoinducer-2-based cell signaling

Autoinducer-2 (AI-2) molecules are used by several microorganisms to modulate various processes, including bioluminescence, biofilm formation, and virulence expression. Certain food matrices, including ground beef extracts, possess compounds capable of inhibiting AI-2 activity. In the present study, we identified and characterized these AI-2 inhibitors from ground beef extract using hexane solvent extraction and gas chromatography. Gas chromatographic analysis revealed the presence of several fatty acids such as palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:omega9), and linoleic acid (C18:omega6) that were capable of inhibiting AI-2 activity. These fatty acids were tested (using Vibrio harveyi BB170 and MM32 reporter strains) at different concentrations (1, 5, and 10 mM) to identify differences in the level of AI-2 activity inhibition. AI-2 inhibition ranged from 25 to 90%. A mixture of these fatty acids (prepared at concentrations equivalent to those present in the ground beef extract) produced 52 to 65% inhibition of AI-2 activity. The fatty acid mixture also negatively influenced Escherichia coli K-12 biofilm formation. These results demonstrate that both medium- and long-chain fatty acids in ground beef have the ability to interfere with AI-2-based cell signaling.     

Phenolic acid composition of sprouted wheats by ultra-performance liquid chromatography (UPLC) and their antioxidant activities

The phenolic acid profiles of flours from two Canadian wheat classes, Canadian Western Red Spring (CWRS) and Canadian Western Amber Durum (CWAD), were investigated using two different extraction mediums and analysed on an ultra-performance liquid chromatography (UPLC) system at different degrees of sprout damage. A sound (non-sprouted) control sample as well as two different sprouted sub-samples, derived from different germination protocols of the control, were prepared for both the CWAD and CWRS. Free phenolic acids were extracted from the ground whole wheat meal using three repetitive 80% ethanol extractions. Bound phenolic compounds were subsequently released from the residue by alkaline hydrolysis followed by triplicate extraction with diethyl ether:ethyl acetate (1:1, v/v). Twelve phenolic acid standards were clearly resolved and quantified using a short 5 min elution gradient. Seven phenolic acids (4-hydroxybenzoic, vanillic, caffeic, syringic, p-coumaric, ferulic and sinapic) were detected in the CWRS and CWAD alcoholic and alkaline extracts. Syringic acid was the main compound in the free phenolic alcoholic extracts of the wheat meal representing 77.0% and 75.3% of the total amount of detected free phenolic compounds for CWRS and CWAD, respectively. However, the major released phenolic compound detected in the alkaline hydrolysed extracts was ferulic acid accounting for 72.3% and 71.0% for CWRS and CWAD respectively total bound phenolics. During germination, syringic acid levels rose as the length of germination time increased, resulting in the increase in total phenolic compound and antioxidant activity of the sprouted wheat flours. There was an increase in total phenolic compounds and the antioxidant activity of the alcoholic extracts from the CWRS and CWAD wheat flours as the germination time was extended. As a result, the sprouted wheats exhibits better nutritional properties than un-germinated wheat and could be used to improve the nutrition value in food products.     

Antimicrobial, antioxidant and phytochemical investigations of sea buckthorn (Hippophaë rhamnoides L.) leaf, stem, root and seed

The antimicrobial and antioxidant activities of crude ethanolic extract from Hippophaë rhamnoides L. (Elaeagnaceae) leaf, stem, root and seed, and their respective fractions, obtained by liquid-liquid extraction (LLE) using hexane (HF), ethyl acetate (EAF) and water (WF), were investigated. The crude extract was obtained by Pressurised Liquid Extraction (PLE), using ethanol at 100 bar and 60 °C. Antimicrobial activity was tested against food-borne and clinical microorganisms. Antioxidant activity was measured using the DPPH-radical scavenging and the ferric reducing antioxidant power (FRAP) assays. The phytochemical contents were examined by colorimetric methods. The results showed that crude extracts were active against Gram − and + strains, and that seed and root extracts were better radical scavengers than leaf and stem extracts. For all organs, the two activities tested were found to be higher in WF. These activities were correlated with the presence of phenolic compounds in active fractions. High Performance Thin Layer Chromatography (HPTLC) fingerprints confirmed presence of phenolic compounds in active extracts and fractions.     

Antioxidant activity of ethanolic extracts of amaranth seeds

Antioxidant activity of ethanolic extracts obtained from two amaranth species was evaluated in a beta-carotene-linoleic acid model system. The addition of amaranth extracts in the range of 0.01-0.1% inhibited degradation of a beta-carotene in a model emulsion during incubation at 60 degrees C; 0.05% addition of amaranth seeds extract was proposed as practically applicable. The total content of phenolic compounds was estimated by the Folin-Ciocalteu method and ranged from 39.17 mg/100 g of Amaranthus caudatus to 56.22 mg/100 g of A. paniculatus seeds. Free phenolic acids contained in ethanolic extracts of amaranth seeds were purified and isolated by solid-phase extraction (SPE) and identified by reversed-phase high-performance liquid chromatography (RP-HPLC). The technique involved gave a good separation of the free phenolic acids in the amaranth seeds. Significant differences in phenolic acids profiles of both amaranth species were observed.     

Extraction of antioxidants from several berries pressing wastes using conventional and supercritical solvents

The solid waste generated in industrial berry juice production was considered as a low cost raw material for the extraction of natural antioxidants. Berries contain phenolic compounds with high antioxidant potential, including anthocyanins, proanthocyanidins, flavonols, catechins, benzoic and cinnamic acids. The solid residues generated from blueberry, cranberry and raspberry after pressing were extracted by conventional solvent extraction or by supercritical CO₂ (SC–CO₂) extraction. The effect of particle size and extraction time on the extraction yield, phenolic yield and phenolic content of the extracts produced by conventional solvents was assessed. Supercritical CO₂ extraction was performed during 2 h operating in the range 80–300 bar at 60 °C using 2.5 L CO₂/h. Maximum solubles yield of 5.20% were extracted from raspberry wastes at 200 bar, 3.89% from cranberry wastes at 250 bar and 1.4% from blueberry wastes at 200 bar. The highest phenolic content of the extracts was observed for blueberry pomace in the trap, with 9 grams of gallic acid equivalents per 100 g of extract. The ABTS (2, 2′-azino-bis-[3-ethylbenzotiazol-6-sulfonic acid]) and DPPH (α,α-diphenyl-β-picrylhydrazyl) radical scavenging capacity of the SC–CO₂ extracts was moderate in comparison with the activity of conventional solvent extracts.     

Nonderivatization analytical method of fatty acids and cis pinonic acid and its application in ambient PM2.5 aerosols in the greater Vancouver area in Canada

A nonderivatization analytical method has been developed to analyze C6-C20 fatty acids and cis-pinonic acid on a GC/ FID and a GC/MSD using a polar DB-FFAP capillary column. On the GC/FID, the response was highly linear over concentration ranges >2 orders of magnitude (R2 = 1.00). Using a mixed solvent of dichloromethane (DCM): methanol (3:1, v/v) and an extraction temperature of 40 degrees C, the method recoveries of the acids from spiked filters were 81-115% based on deuterated surrogates, and the relative standard deviations were <12%. The recoveries were mainly controlled by the extraction temperature. At 40 degrees C the acids in sample extracts were stable for at least 12 months, while at 80 degrees C, unintended esterization of the acids by methanol was found that reduces their stability in the sample extracts. The analysis of the acids in PM2.5 samples from NIST using this nonderivatization method showed that the efficiency and accuracy were comparable to the derivatization method. Compared with existing derivatization methods, the method is accurate and sensitive, yet simple to use. This method was applied to PM2.5 ambient aerosols collected from a forest site and at a traffic tunnel outlet in the greater Vancouver area in Canada. Total fatty acids (sum of C6-C20) in the aerosols were measured as 20.2-138.7 ng/m3 at the forest site and 100.2-264.6 ng/m3 at the tunnel site. The cis-pinonic acid concentrations were 1.6-44.2 ng/m3 in the forest and from below detection to 6.5 ng/m3 at the tunnel outlet.