Closed-loop Stripping Analysis Research Articles

Chemical and Electrophysiological Characterisation of Headspace Volatiles from Yeasts Attractive to Drosophila suzukii

Chemical control of Drosophila suzukii (Diptera: Drosophilidae) based on the use of insecticides is particularly challenging as the insect attacks ripening fruits shortly before harvest. An alternative strategy may rely on the use of yeasts as phagostimulants and baits, applied on canopy as attract-and-kill formulations. The aim of this research was to identify the most attractive among six yeast species for D. suzukii: Saccharomyces cerevisiae, Hanseniaspora uvarum, Clavispora santaluciae, Saccharomycopsis vini, Issatchenkia terricola, and Metschnikowia pulcherrima. The volatile profile of C. santaluciae was described for the first time. Behavioural experiments identified H. uvarum and S. vini as the most attractive yeasts. The characterization of yeast headspace volatiles using direct headspace (DHS) and solid-phase microextraction (SPME) revealed several strain-specific compounds. With DHS injection, 19 volatiles were characterised, while SPME revealed 71 compounds constituting the yeast headspace. Both analyses revealed terpenoids including β-ocimene, citronellol, (Z)-geraniol (nerol), and geranial as distinct constituents of S. vini. H. uvarum and S. vini were further investigated using closed-loop stripping analysis (CSLA) and electroantennography. Out of 14 compounds quantified by CSLA, ethyl acetate, isoamyl acetate, β-myrcene, benzaldehyde and linalool were detected by D. suzukii antennae and might generate the strong attractiveness of S. vini and H. uvarum. Our results highlight a strong attraction of D. suzukii to various yeasts associated with both the flies and their habitat and demonstrate how different sampling methods can impact the results of volatile compound characterization. It remains to be demonstrated whether the distinct attraction is based on special adaptations to certain yeasts and to what extent the metabolites causing attraction are interchangeable.

Identification of 3-(trifluoromethyl)phenol as the malodorous compound in a pollution incident in the water supply in Catalonia (N.E. Spain).

A study of organic compounds that caused a serious taste and odor episode of water supply in two residential areas in Catalonia (N.E. Spain) was carried out. Sweet and paint/solvent odor were the main descriptors used by consumers. Some cases of sickness and nausea were also associated with drinking water consumption by the consumers. Closed-loop stripping analysis (CLSA) combined with sensory gas chromatography and gas chromatography mass spectrometry detection were used to study the problem. As a result, 3-(trifluoromethyl)phenol (CAS number 98-17-9) was for the first time identified as a responsible of an odor incident in drinking water. Concentration levels of this compound were up to 17,000ng/L in groundwater and up to 600ng/L in distributed water. Odor threshold in water for 3-(trifluoromethyl)phenol was determined as 13ng/L (45°C).

Diel rhythms in the volatile emission of apple and grape foliage

This study investigated the diel emission of volatile organic compounds (VOCs) from intact apple (Malus x domestica Borkh., cv. Golden Delicious) and grape (Vitis vinifera L., cv. Pinot Noir) foliage. Volatiles were monitored continuously for 48 h by proton transfer reaction - time of flight - mass spectrometry (PTR-ToF-MS). In addition, volatiles were collected by closed-loop-stripping-analysis (CLSA) and characterized by gas chromatography-mass spectrometry (GC-MS) after 1 h and again 24 and 48 h later. Fourteen and ten volatiles were characterized by GC-MS in apple and grape, respectively. The majority of these were terpenes, followed by green leaf volatiles, and aromatic compounds. The PTR-ToF-MS identified 10 additional compounds and established their diel emission rhythms. The most abundant volatiles displaying a diel rhythm included methanol and dimethyl sulfide in both plants, acetone in grape, and mono-, homo- and sesquiterpenes in apple. The majority of volatiles were released from both plants during the photophase; whereas methanol, CO2, methyl-butenol and benzeneacetaldehyde were released at significantly higher levels during the scotophase. Acetaldehyde, ethanol, and some green leaf volatiles showed distinct emission bursts in both plants following the daily light switch-off. These new results obtained with a combined analytical approach broaden our understanding of the rhythms of constitutive volatile release from two important horticultural crops. In particular, diel emission of sulfur and nitrogen-containing volatiles are reported here for the first time in these two crops.

Simultaneous determination of the potential carcinogen 1,4-dioxane and malodorous alkyl-1,3-dioxanes and alkyl-1,3-dioxolanes in environmental waters by solid-phase extraction and gas chromatography tandem mass spectrometry

1,4-dioxane is a synthetic industrial solvent used in various industrial processes, and it is a probable human carcinogen whose presence in the aquatic environment is frequently reported. Alkyl-1,3-dioxanes and alkyl-1,3-dioxolanes are compounds that have been identified as causing several odor episodes in waters over the last years, with the result of downtime of drinking water treatment plants. According to published studies, some of these episodes may be caused either by resins synthesis processes, or by industrial residues added to dehydrated sludge in wastewater treatment plants (WWTPs) in order to increase biogas production efficiency.Analytical methods based on closed loop stripping analysis (CLSA) are routinely used when taste and odor events appear, but this technique has demonstrated to be unsuitable to determine 1,4-dioxane at trace levels. In this context, drinking water companies tend to focus on determining odorous compounds, but not on those compounds that are potentially harmful.The suitability of a SPE method and further analysis by GC/MS–MS to simultaneously determine 1,4-dioxane and alkyl-1,3-dioxanes and dioxolanes has been demonstrated. Recoveries in surface waters spiked at 25ng/L ranged from 76% to 105%, whereas method quantification limits (MQLs) varied from 0.7 to 26ng/L for dioxanes, and dioxolanes and 50ng/L for 1,4-dioxane. Uncertainties were evaluated at two different concentrations, 0.02μg/L and 0.4μg/L, with values of 25% for 1,4-dioxane, and of 16–28% for alkyl-1,3-dioxanes and alkyl-1,3-dioxolanes for the later. The methodology has been successfully applied to samples from the aquifer of the Llobregat River (NE. Spain).

Current antibiogram pattern of Salmonella typhi and paratyphi isolates and response to treatment in a tertiary care centre

Objective: The objective of this study is to study the current antibiotic sensitivity pattern of Salmonella typhi and paratyphi isolates and the clinical response of children with culture positive enteric fever (EF) to the specific antibiotic used as suggested by the sensitivity pattern. Materials and Methods: This is a retrospective study analyzing the records of 197 children treated for blood culture positive EF during 3 years from January 2013 to December 2015. Antibiogram pattern of S. typhi/paratyphi and response pattern to the antibiotic used as per antibiogram were analyzed. Kirby Bauer’s disc diffusion method was used for antibiotic sensitivity using closed-loop stripping analysis standards. Temperature charts of the patients analyzed for response patternof fever to the antibiotic started. Results: 197 culture positive cases were included in the study (S. typhi=190 and paratyphi=7). Sensitivity pattern to 9 out of 10 antibiotics tested was high and was low only to nalidixic acid (6.3%). There were 184 (93.4%) children whose antibiogram showed high sensitivity to cephalosporins and were treated with intravenous ceftriaxone (Group 1). The majority of children in this group (172/184, 93.5%) became afebrile by 7 days of therapy. 13 (6.6%) children whose antibiogram showed resistance to cephalosporins were treated with intravenous ciprofloxacin (Group 2). 9 of this group became afebrile by 7 days. 12 children from Group 1 and 4 children from Group 2 were considered as either reduced susceptibility or resistance torespective antibiotics and were treated with either azithromycin or piperacillin-tazobactam over the next 5-7 days successfully. Conclusion: Appropriate diagnosis using blood cultures and using 3rd generation cephalosporins as the first line of the drug in treating children with EF can reduce the duration of treatment, promote better compliance, reduce relapse rates, and may help decrease multi-drug resistant S.typhi/partyphi strains in the community..

Determination of dimethyl selenide and dimethyl sulphide compounds causing off-flavours in bottled mineral waters

Sales of bottled drinking water have shown a large growth during the last two decades due to the general belief that this kind of water is healthier, its flavour is better and its consumption risk is lower than that of tap water. Due to the previous points, consumers are more demanding with bottled mineral water, especially when dealing with its organoleptic properties, like taste and odour. This work studies the compounds that can generate obnoxious smells, and that consumers have described like swampy, rotten eggs, sulphurous, cooked vegetable or cabbage. Closed loop stripping analysis (CLSA) has been used as a pre-concentration method for the analysis of off-flavour compounds in water followed by identification and quantification by means of GC-MS. Several bottled water with the aforementioned smells showed the presence of volatile dimethyl selenides and dimethyl sulphides, whose concentrations ranged, respectively, from 4 to 20 ng/L and from 1 to 63 ng/L. The low odour threshold concentrations (OTCs) of both organic selenide and sulphide derivatives prove that several objectionable odours in bottled waters arise from them. Microbial loads inherent to water sources, along with some critical conditions in water processing, could contribute to the formation of these compounds. There are few studies about volatile organic compounds in bottled drinking water and, at the best of our knowledge, this is the first study reporting the presence of dimethyl selenides and dimethyl sulphides causing odour problems in bottled waters.

Streptopyridines, volatile pyridine alkaloids produced by Streptomyces sp. FORM5.

Streptomyces sp. FORM5 is a bacterium that is known to produce the antibiotic streptazolin and related compounds. We investigated the strain for the production of volatiles using the CLSA (closed-loop stripping analysis) method. Liquid and agar plate cultures revealed the formation of new 2-alkylpyridines (streptopyridines), structurally closely related to the already known 2-pentadienylpiperidines. The structures of the streptopyridines A to E were confirmed by total synthesis. The analysis of the liquid phase by solvent extraction or extraction with an Oasis adsorbent showed that streptazolin and 2-pentadienylpiperidine are the major compounds, while the streptopyridines are only minor components. In the gas phase, only the streptopyridines could be detected. Therefore, an orthogonal set of analysis is needed to assess the metabolic profile of bacteria, because volatile compounds are obviously overlooked by traditional analytical methods. The streptopyridines are strain specific volatiles that are accompanied by a broad range of headspace constituents that occur in many actinomycetes. Volatiles might be of ecological importance for the producing organism, and, as biosynthetic intermediates or shunt products, they can be useful as indicators of antibiotic production in a bacterium.

Elicitors of tansy volatiles from cotton leafworm larval oral secretion

The feeding of Spodoptera littoralis and Autographa gamma caterpillars on tansy leaves led to a complete different release of volatile monoterpenes, sesquiterpenes, and hexenyl alkanoates. Volatiles were collected from S. littoralis and A. gamma larvae damaged, mechanically wounded, and excised tansy leaves by closed loop stripping analysis. The qualitative and quantitative determination of the volatiles were done by GC-MS- and GC-measurements. The oligosaccharides sucrose, raffinose, stachyose, and verbascose have been detected in oral secretion of the caterpillars of the cotton leafworm S. littoralis. When applied to damaged leaves of tansy plants, these oligosaccharides induce the tansy leaves to emit a similar volatile blend as the feeding of S. littoralis larvae.

2H‐Pyran‐2‐ones from Trichoderma viride and Trichoderma asperellum

AbstractVolatiles emitted by the soil fungi Trichoderma viride 272 and Trichoderma asperellum 328 were collected by using the closed loop stripping analysis (CLSA) headspace technique, and the obtained extracts were analysed by GC/MS. Several alkyl‐ and alkenyl‐2H‐pyran‐2‐ones, including known compounds 6‐pentyl‐2H‐pyran‐2‐one and (E)‐6‐(pent‐1‐en‐1‐yl)‐2H‐pyran‐2‐one, and the new derivatives (E)‐6‐(pent‐2‐en‐1‐yl)‐2H‐pyran‐2‐one, 6‐propyl‐2H‐pyran‐2‐one, and 6‐heptyl‐2H‐pyran‐2‐one were found. The alkenyl derivative (E)‐6‐(hept‐1‐en‐1‐yl)‐2H‐pyran‐2‐one, previously tentatively identified from a marine Botrytis by MS analysis, was also detected. All alkenyl pyrones were synthesised by using a reported Stille coupling followed by lactonisation, whereas the alkylated pyrones were obtained through a reported synthetic approach by radical bromination of 5‐alkylpent‐2‐en‐5‐olides and dehydrobromination. Because the yields in both cases were not satisfactory and fell a long way short of the yields reported for similar compounds, all compounds were synthesised again using a gold‐catalysed coupling of terminal alkynes with propiolic acid recently developed by Schreiber and co‐workers, giving high yields in all cases. A comparison of the synthetic methods is given.

The volatiles of pathogenic and nonpathogenic mycobacteria and related bacteria

Volatiles released by pathogenic and nonpathogenic mycobacteria, as well as by mycobacteria-related Nocardia spp., were analyzed. Bacteria were cultivated on solid and in liquid media, and headspace samples were collected at various times during the bacterial lifecycle to elucidate the conditions giving optimal volatile emission. Emitted volatiles were collected by using closed-loop stripping analysis (CLSA) and were analyzed by gas-chromatography–mass-spectrometry. A wide range of compounds was produced, although the absolute amount was small. Nevertheless, characteristic bouquets of compounds could be identified. Predominantly aromatic compounds and fatty-acid derivatives were released by pathogenic/nonpathogenic mycobacteria, while the two Nocardia spp. (N. asteroides and N. africana) emitted the sesquiterpene aciphyllene. Pathogenic Mycobacterium tuberculosis strains grown on agar plates produced a distinct bouquet with different volatiles, while liquid cultures produce less compounds but sometimes an earlier onset of volatile production because of their steeper growth curves under this conditions. This behavior differentiates M. tuberculosis from other mycobacteria, which generally produced fewer compounds in seemingly lower amounts. Knowledge of the production of volatiles by M. tuberculosis can facilitate the rational design of alternative and faster diagnostic measures for tuberculosis.

Analysis of polysulfides in drinking water distribution systems using headspace solid-phase microextraction and gas chromatography–mass spectrometry

Sulfide and polysulfides are strong nucleophiles and reducing agents that participate in many environmentally significant processes such as the formation of sulfide minerals and volatile organic sulfur compounds. Their presence in drinking water distribution systems are of particular concern and need to be assessed, since these species consume disinfectants and dissolved oxygen, react with metal ions to produce insoluble metal sulfides, and cause taste and odour problems. The analysis of sulfide and polysulfides in drinking water distribution systems is challenging due to their low concentrations, thermal instability and their susceptibility to undergo oxidation and disproportionation reactions. This paper reports on the development and optimisation of a rapid, simple, and sensitive method for the determination of sulfide and polysulfides in drinking water distribution systems. The method uses methyl iodide to derivatise sulfide and polysulfides into their corresponding dimethyl(poly)sulfides, which are then extracted using solid-phase microextraction in the headspace mode and analysed by gas chromatography–mass spectrometry. Good sensitivity was achieved for the analysis of dimethyl(poly)sulfides, with detection limits ranging from 50 to 240 ng L −1. The method also demonstrated good precision (repeatability: 3–7%) and good linearity over two orders of magnitude. Matrix effects from raw drinking water containing organic carbon (3.8 mg L −1) and from sediment material from a drinking water distribution system were shown to have no interferences in the analysis of dimethyl(poly)sulfides. The method provides a rapid, robust, and reliable mean to analyse trace levels of sulfides and polysulfides in aqueous systems. The new method described here is more accessible and user-friendly than methods based on closed-loop stripping analysis, which have been traditionally used for the analysis of these compounds. The optimised method was used to analyse samples collected from various locations in a drinking water distribution system. Some of the samples were shown to contain inorganic polysulfides, and their presence was associated with high sediment density in the system and the absence of disinfectant residual in the bulk water.

Identification of Alkyl-methoxypyrazines as the Malodorous Compounds in Water Supplies from Northwest Spain

A study of organic compounds which caused several odor problems in water supplies from NW Spain was carried out. Sour dish-cloths, potato bin and musty were the main descriptors associated with these events. Closed loop stripping analysis combined with sensory-GC and GC/MS detection was used. The compound producing the initial odor event was 3,5-dimethyl-2-methoxypyrazine, identified for the first time as the compound responsible for odor incidents in finished water. Concentration levels were up to 300 ng/L in the effluent from an activated sludge wastewater treatment plant (WWTP) and 3 ng/L in finished water. 3-isobutyl-2-methoxypyrazine and other alkyl methoxypyrazines were the compounds responsible for the odor events that occurred several months later. Concentration levels in the mg/L range were measured in the activated sludge of a WWTP.

Disinfection by-products from halogenation of aqueous solutions of terpenoids

We report the formation of trihalomethanes and other disinfection by-products from four polyfunctional terpenoids during simulated chlorination of natural waters. Complex suites of products were identified by closed loop stripping analysis (CLSA)/gas chromatography–mass spectrometry (GC–MS) from halogenation of β-carotene and retinol. β-Ionone appeared to be a key intermediate in the halogenation of β-carotene and retinol, reacting further under the reaction conditions to produce trans-β-ionone-5,6-epoxide and β-cyclocitral. Halogenation of the four terpenoids also produced trihalomethanes (THMs), most likely through haloform reaction on methyl ketone groups within many of the intermediates. Since halogenation of retinol produced a significant quantity of THMs at a slow reaction rate, retinol-based structures may possibly contribute to the slow reacting phase of THM formation in natural waters. Two polyhydroxyphenol model compounds were halogenated for comparison. The only products identified by CLSA/GC–MS from halogenation of 4′,5,7-trihydroxyflavanone and ellagic acid were THMs. 4′,5,7-Trihydroxyflavanone rapidly produced THMs, with an extremely high molar yield (94%) at pH 7. Terpenoids of the β-ionone and retinol type should be considered to be significant THM precursors, while 4′,5,7-trihydroxyflavanone has been shown to be an extremely significant THM precursor, potentially present within natural organic matter in water treatment processes and distribution systems.

Sesquiterpenes of the Geosmin-Producing Cyanobacterium Calothrix PCC 7507 and their Toxicity to Invertebrates

The occurrence of sesquiterpenes was investigated with the geosmin-producing cyanobacterium Calothrix PCC 7507. The essential oil obtained by vacuum destillation was studied in more detail by GC-MS methods and superposition with authentic compounds. Geosmin was the dominating compound while the other sesquiterpenes were minor components. Sesquiterpenes that have not been described before in cyanobacteria were isodihydroagarofuran, eremophilone and 6,11-epoxyisodaucane. Closed-loop stripping analysis revealed that most of the sesquiterpenes were found in the biomass of Calothrix, while eremophilone was mainly observed in the medium of the axenic culture. Eremophilone showed acute toxicity (LC50) against Chironomus riparius (insecta) at 29 microM and against Thamnocephalus platyurus (crustacea) at 22 microM. The compound was not toxic for Plectus cirratus (nematoda). 6,11-Epoxyisodaucane and isodihydroagarofuran exhibited no toxicity to invertebrates when applied in concentrations up to 100 microM.

Use of CLSA and SPME-Headspace Techniques Followed by GC-MS Analysis to Extract and Identify the Floral Odorants

Flowers of Ziziphus spina christi are known to be attractive for parasitoids and predators. In Y-tube olfactometer experiments, the dried flowers attracted significantly (p < 0.001) the female parasitoids Aphelinus abdominalis. The flower volatile compounds were analyzed to understand which compounds could be specifically responsible for this attractiveness. The volatile compounds of Ziziphus flowers were extracted by closed-loop-stripping-analysis (CLSA) and also by solid phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) analysis. The main chemical classes of the volatile compounds are aldehydes, monoterpene-alcohols, ketones and hydrocarbons. Flower extract and some specific compounds will be further tested for their responsiveness to predators and parasitoids in behavioural and electrophysiological experiments.

Validation of Geosmin and 2-Methyl-i-Borneol Analysis by CLSA-GC-FID Method to Obtain ISO-17025 Accreditation

A study of the accreditation process using closed loop stripping analysis (CLSA)-gas chromatography (GC)-flame ionization detection (FID) methodology for the analysis of geosmin and 2-methyl-i-borneol (MIB) is performed, completing the instrumental validation process. Quality parameters, such as the linearity ranges, repeatability and reproducibility, efficiencies, matrix effects, and interference, are presented. The experimental work is completed with a study of the associated uncertainty using a "Bottom-up Approach Method" and a short description of a control-protocol for preserving the validation conditions as a method of quality assurance protocol. The results show that CLSA-GC-FID-MS is a very good tool for the analysis of geosmin and MIB at a low level threshold, and the working range obtained is 10-400 ppt (ng/L) for geosmin and 15-400 ppt for MIB, respectively, in both drinking and natural waters. Uncertainty was approximately 16% for both compounds; good reproducibility with precision below 10% and bias between 85-90% for the three matrices considered are obtained.

The effect of white or grey PVC pipe and its joint solvents (primer and cement) on odour problems in drinking water distribution systems

A study of the production of odour-causing compounds was conducted from the leaching of polyvinylchloride (PVC) pipe and its joints, primer and cement, into drinking water distribution systems. Flavour Profile Analysis (FPA), closed-loop stripping analysis--gas chromatography/mass spectrometry (CLSA-GC/MS) and sensory-GC analysis of white or grey PVC alone found no odour-causing compounds produced during the leaching experiments. FPA analysis of the PVC's primer and cement leached alone and/or when applied to grey or white PVC pipes produced a glue/varnish odour. A sweet/phenolic odour replaced the glue/varnish odour after the leached media were diluted with Milli-Q water to threshold odour intensity. Three compounds were responsible for the sweet/phenolic odour and were observed by sensoryGC analysis. The leaching study of the PVC pipe with its joint solvents (primer and cement) concluded that the original solvent compounds, and their reaction products that formed during the bonding process on the PVC pipe, were a primary source of the glue/varnish odour. The original compounds of the PVC primer and cement were not detected by CLSA-GC/MS, due to their high volatility during the CLSA extraction method and/or these compounds appeared in a solvent peak of the GC/MS analysis. However, the original primer and cement chemicals (acetone, tetrahydrofuran, methyl ethyl ketone, and cyclohexanone) had a glue/varnish odour. A total of nine odorous GC peaks were produced as reaction products from leaching of primer in water and white or grey PVC pipe with primer and cement, and white or grey PVC with primer only. None of these compounds were among the chemical ingredients in the original primer or cement. Four GC peaks with a sweet/phenolic odour were present due to the reaction products of the cement leached with white or grey PVC. None of these compounds were positively identified.

Volatile profiles of sparkling wines obtained by three extraction methods and gas chromatography–mass spectrometry (GC–MS) analysis

Simultaneous distillation extraction (SDE) and closed-loop stripping analysis (CLSA) show great capacity for organic compound extraction. Here we used these techniques to obtain and characterize a wide range of volatile compounds from aged cava sparkling wine. We also explored the potential application of head space-solid phase micro extraction (HS-SPME) to determine the distinctive volatile compounds of aged cava as this technique is a common extraction method in quality flavour control. For SDE, 50 mL of cava were extracted with pentane/dichloromethane during 4 h in a Likens–Nickerson (LN) extraction apparatus; while for CLSA, 25 mL of cava were stirred during 1 h into a CLSA apparatus with an adsorbent trap of granulated activated carbon. HS-SPME was performed at 35 °C using 2 ml of sample for 30 min. The 20-mm SPME fibber was coated with a 50/30-μm layer of divinylbenzene–carboxen–polydimethylsiloxane (DVB–CAR–PDMS). All the extraction methods were followed by gas chromatography–mass spectrometry (GC–MS) analysis. SDE and CLSA allowed the identification of 84 volatile compounds. Almost 40% of the volatiles from these two techniques were obtained by HS-SPME. Moreover, here we provide the first description of several tentatively identified compounds such as lilial, octanal, 2-octanone, isopropyl disulfide, methylthiophen-3-one, α-amyl-cinnamaldehyde, ethyl 2-furancarboxylate, 2-acetylfuran, and 5-methylfurfural in cava.

Comparative study of different extraction techniques for the analysis of virgin olive oil aroma

Headspace solid-phase microextraction (HS-SPME), simultaneous distillation/extraction (SDE) and closed-loop stripping analysis (CLSA) coupled to gas chromatography/mass spectrometry (GC/MS) were used to study virgin olive oil, with the goal of detecting large numbers of characteristic volatile and semi-volatile compounds. More than one hundred compounds were detected in the olive oil extracts, and their percent amounts obtained by each technique were calculated. Qualitative and quantitative differences of virgin olive oil volatile profiles were observed applying the three extraction techniques. SPME showed a higher affinity for alcohols and ketones, while CLSA achieved the highest percentages of esters and hydrocarbons. Finally, the highest extraction of total terpenoid compounds occurred with SDE and CLSA, where CLSA allowed extracting the highest percentages of the most of them. SDE extraction caused the thermal degradation of the oil sample, which resulted in a high percentage of aldehydic compounds.

Development of a closed loop stripping analysis using solid-phase microextraction to analyze geosmin and MIB in drinking water

A novel analytical method, solid phase microextraction (SPME) coupled with closed loop stripping analysis (CLSA), was introduced for the analysis of MIB and geosmin at nanogram per liter concentration levels. The optimum CLSA/SPME analysis conditions of 65 °C, 60-minute extraction time, and 0.5 M sodium sulfate were determined from a statistical design. The individual Kfw of MIB and geosmin from CLSA/SPME method was 4.21 and 4.85, and resulted an order of magnitude greater than the Kfw obtained from direct SPME method. A detection limit of 10 ng/L of MIB and geosmin was achieved by GC-MS with CLSA/SPME with a polyacrylate phase. Overall, CLSA/SPME provides a fast, solvent-free, and less labor intensive method compared to the standard CLSA. The CLSA/SPME method is a valuable alternative method for the analysis of taste-and-odor causing compounds in drinking water.