Rapid and simultaneous determination of ten off-flavor compounds in water by headspace solid phase microextraction and gas chromatography-mass spectrometry

A simple and sensitive analytical procedure for the determination of multi-component compounds in water samples was developed and optimized using the headspace solid-phase microextraction(HSSPME) coupled with gas chromatography-mass spectrometry(GC-MS). Ten off-flavor compounds, including geosmin(GSM), 2-methylisoborneol(2-MIB), 2-isopropyl-3-methoxypyrazine(IPMP), 2-isobutyl-3-methoxypyrazine(IBMP), β-ionone, trans-2,cis-6-nonadienal(NDE), 2,3,4-trichloroanisole(2,3,4-TCA), 2,3,6-trichroloanisole(2,3,6-TCA), 2,4,6-trichloroanisole(2,4,6-TCA), and 2,4,6-tribromoanisole(2,4,6-TBA) were used as the target analytes. The optimization of extraction parameters including fibers types, extraction time, extraction temperature, stirring rate, sample volume, and ionic strength was carried out through the univariate approach. Ten off-flavor compounds were quantified within 50 min under the optimal conditions. Calibration curves with good linearity(r^2=0.990-0.998) were obtained in the range 1.0/2.0-100 ng/L, while the limits of detection for all compounds were lower than or close to the odor threshold concentration. Furthermore, the proposed method was applied to analyzing and determining the off-flavor compounds in real water samples from water-treatment plants.

Determination of Aroma Composition of Santalum album Linn by Solid-phase Microextraction-Gas Chromatography-Mass Spectrometry

[Objectives]This study aimed to determine the volatile components in Santalum album Linn and gradually clarify the aroma composition of S.album Linn.[Methods]Solid-phase microextraction method was used to obtain the volatile components of S.album Linn.The aroma components were analyzed by gas chromatography-mass spectrometry and their relative contents were calculated using the area normalization method.[Results]In a dry state at room temperature,39 chemical components were identified from S.album Linn,mainly olefins(91.15%),alkanes(3.00%),alcohols(2.56%),esters(2.19%),ketones(0.55%),aldehydes(0.41%)and heterocyclics(0.14%).[Conclusions]This method has the advantages of low sample consumption,easy operation,rapid identification of aroma components and high sensitivity,and can effectively separate and determine volatile components in S.album Linn,realizing the rapid identification of different S.album Linn varieties and providing technical support for further research on Chinese medicinal materials.

Determination of Aromatic Components of Rosa davurica Pall. by Headspace Solid Phase Microextraction Combined with GC-MS

[Objectives] To determine the aromatic components of Rosa davurica Pall. [Methods] 42 kinds of aromatic components were identified from the flowers of R. davurica by headspace solid phase microextraction( HS-SPME) combined with gas chromatography-mass spectrometry( GC-MS). The main compounds were alcohols( 54. 88%) and aldehydes( 19. 55%). [Results] The top five components with the highest relative content were phenylethyl alcohol( 12. 69%),geraniol( 9. 85%),citronellol( 8. 80%),nerol( 7. 84%) and 2-n-pentylfuran( 7. 45%). [Conclusions] Headspace solid phase microextraction( HS-SPME) combined with gas chromatography-mass spectrometry( GC-MS) can provide basis for further development and utilization of R. davurica.

Preparation of polypyrrole/nanosilica composite for solid-phase microextraction of bisphenol and phthalates migrated from containers to eye drops and injection solutions

This paper describes the electrodeposition of polyphosphate-doped polypyrrole/nanosilica nano-composite coating on steel wire for direct solid-phase microextraction of bisphenol A and five phthalates. We optimized influencing parameters on the extraction efficiency and morphology of the nanocomposite such as deposition potential, concentration of pyrrole and polyphosphate, deposition time and the nanosilica amount. Under the optimized conditions, characterization of the nanocomposite was inves-tigated by scanning electron microscopy and Fourier transform infra-red spectroscopy. Also, the factors related to the solid-phase microextraction method including desorption temperature and time, extrac-tion temperature and time, ionic strength and pH were studied in detail. Subsequently, the proposed method was validated by gas chromatography-mass spectrometry by thermal desorption and acceptable figures of merit were obtained. The linearity of the calibration curves was between 0.01 and 50 ng/mL with acceptable correlation coefficients (0.9956-0.9987) and limits of detection were in the range 0.002-0.01 ng/mL. Relative standard deviations in terms of intra-day and inter-day by five replicate analyses from aqueous solutions containing 0.1 ng/mL of target analytes were in the range 3.3%-5.4% and 5%-7.1%, respectively. Fiber-to-fiber reproducibilities were measured for three different fibers prepared in the same conditions and the results were between 7.3% and 9.8%. Also, extraction recoveries at two different concentrations were ≥96%. Finally, the suitability of the proposed method was demonstrated through its application to the analysis of some eye drops and injection solutions.

Covalent organic nanospheres as a fiber coating for solid-phase microextraction of genotoxic impurities followed by analysis using GC-MS

Covalent organic nanospheres(CONs)were explored as a fiber coating for solid-phase microextraction of genotoxic impurities(GTIs)from active ingredients(AIs).CONs were synthesized by an easy solutionphase procedure at 25℃.The obtained nanospheres exhibited a high specific surface area,good thermostability,high acid and alkali resistance,and favorable crystallinity and porosity.Two types of GTIs,alkyl halides(1-iodooctane,1-chlorobenzene,1-bromododecane,1,2-dichlorobenzene,1-bromooctane,1-chlorohexane,and 1,8-dibromooctane)and sulfonate esters(methyl p-toluenesulfonate and ethyl ptoluenesulfonate),were chosen as target molecules for assessing the performance of the coating.The prepared coating achieved high enhancement factors(5097-9799)for the selected GTIs.The strong affinity between CONs and GTIs was tentatively attributed to π-π and hydrophobicity interactions,large surface area of the CONs,and size-matching of the materials.Combined with gas chromatography-mass spectrometry(GC-MS),the established analytical method detected the GTIs in capecitabine and imatinib mesylate samples over a wide linear range(0.2-200 ng/g)with a low detection limit(0.04-2.0 ng/g),satisfactory recovery(80.03%-109.5%),and high repeatability(6.20%-14.8%)and reproducibility(6.20%-14.1%).Therefore,the CON-coated fibers are promising alternatives for the sensitive detection of GTIs in AI samples.

Solid-phase microextraction for flavor analysis in Harari Khat （Catha edulis） stimulant

This research examined the typical flavor compounds in the commonest type of Khat called Harari Khat grown in the region of Ethiopia.Twenty-eight compounds, which includes 1,2-Propanedione,1-Phenyl,Hexanol,Hexanal compounds,Limonene, Benzaldehyde with other flavors, were extracted by polydimethylsiloxane at room temperature for 30min from Khat samples,and identified by solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS).This method needs no organic solvents and required minimal sample.

Determination of organochlorine pesticides from juice samples using magnetic biochar-based dispersive micro-solid phase extraction in combination with dispersive liquid-liquid microextraction

Analysis of pesticide residue levels in juice beverages is important to ensure safe consumption and avoid global trade concerns associated to pesticide contaminations.A simple,inexpensive and effective method was developed for the determination of organochlorine pesticides(OCPs)in bottled juice drinks using GC-MS.Sample pretreatment was performed using dispersive solid-phase microextraction(D-μ-SPE)for matrix desorption and dispersive liquid-liquid microextraction(DLLME)for analyte enrichment.In this study,an affordable and effective sorbent for the adsorption of OCPs from juice samples was synthesized from avocado seeds mixed with magnetic precursors for D-μSPE.The ground avocado seeds combined with a magnetic precursor nanocomposite were characterized using various instruments including scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and Brunauer-Emmett-Teller(BET)analysis.The solution obtained from D-μ-SPE desorption was used as a dispersant for the subsequent DLLME,which made the combination of D-μ-SPE with DLLME much easier.The effectiveness of the method was enhanced by optimizing the influential parameters in both D-μ-SPE and DLLME.Then after,the optimal values were determined for the real sample analysis.Accordingly,there was good linear dynamic range with a coefficient of determination(r2)≥0.9989.The limit of detection and quantification were 0.02–0.69 and 0.06–2.10 ng/L respectively.The method showed high enrichment factors ranging from 96 to 313 with recoveries of 87–100%.Intraday and interday precisions were≤4%.Compared with other reported methods,this method is a one-step,simple,cheap,fast,and environmentally friendly alternative and straightforward method for adsorbing organochlorine pesticides from sample solutions.These results demonstrates the high potential of the proposed method for the extraction and cleanup of contaminants in selected juices and other related samples.

Modern approaches for detection of volatile organic compounds in metabolic studies focusing on pathogenic bacteria:Current state of the art

Pathogenic microorganisms produce numerous metabolites,including volatile organic compounds(VOCs).Monitoring these metabolites in biological matrices(e.g.,urine,blood,or breath)can reveal the presence of specific microorganisms,enabling the early diagnosis of infections and the timely implementation of tar-geted therapy.However,complex matrices only contain trace levels of VOCs,and their constituent com-ponents can hinder determination of these compounds.Therefore,modern analytical techniques enabling the non-invasive identification and precise quantification of microbial VOCs are needed.In this paper,we discuss bacterial VOC analysis under in vitro conditions,in animal models and disease diagnosis in humans,including techniques for offline and online analysis in clinical settings.We also consider the advantages and limitations of novel microextraction techniques used to prepare biological samples for VOC analysis,in addition to reviewing current clinical studies on bacterial volatilomes that address inter-species in-teractions,the kinetics of VOC metabolism,and species-and drug-resistance specificity.

A new method of simultaneous determination of atmospheric amines in gaseous and particulate phases by gas chromatography-mass spectrometry

As more attention is being paid to the characteristics of atmospheric amines,there is also an increasing demand for reliable detection technologies.Herein,a method was developed for simultaneous detection of atmospheric amines in both gaseous and particulate phases using gas chromatography-mass spectrometry(GC-MS).The amine samples were collected with and without phosphoric acid filters,followed by derivatization with benzenesulfonyl chloride under alkaline condition prior to GC-MS analysis.Furthermore,the method was optimized and validated for determining 14 standard amines.The detection limits ranged from0.0408-0.421μg/mL(for gaseous samples)and 0.163-1.69μg/mL(for particulate samples),respectively.The obtained recoveries ranged from 68.8%-180%and the relative standard deviation was less than 30%,indicating high precision and good reliability of the method.Seven amines were simultaneously detected in gaseous and particulate samples in an industrial park using the developed method successfully.Methylamine,dimethylamine and diethylamine together accounted for 76.7%and 75.6%of particulate and gaseous samples,respectively.By comparing the measured and predicted values of gas-particle partition fractions,it was found that absorption process of aqueous phase played a more important role in the gas-partition of amines than physical adsorption.Moreover,the reaction between unprotonated amines and acid(aq.)in water phase likely promoted water absorption.Higher measured partition fraction of dibutylamine was likely due to the reaction with gaseous HCl.The developed method would help provide a deeper understanding of gas-particle partitioning as well as atmospheric evolution of amines.

Ultrasound-Assisted Low-Density Solvent Dispersive Liquid-Liquid Extraction for the Determination of Amphetamines in Biological Samples Using Gas Chromatography-Mass Spectrometry

In order to control drug crime effectively,it is necessary to develop selective analytical methods suitable for unambiguous identification and determination of drugs in illicit samples and biological matrices.A novel microextraction technique based on ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction,(UA-LDS-DLLME)has been applied to the determination of four amphetamines(methamphetamine,amphetamine,3,4-methylenedioxymethamphetamine,and 3,4-methylenedioxyamphetamine)in urine samples by gas chromatography-mass spectrometry.The parameters affecting extraction efficiency have been investigated and optimized.UA-LDS-DLLME used ultrasound energy to assist in the emulsification process without any disperser solvent.Under the optimized conditions,linearity was observed for all analytes in the 0.15-10 p,g/mL range with correlation coefficients(R)ranging from 0.9886 to 0.9894.The recoveries of75.6-91.4%with relative standard deviations of 2.5-4.0%were obtained.The limits of detection(S/N=3)were estimated to be in the 5-10 ng/mL range.The UA-LDS-DLLME technique had the advantages of shorter extraction time,suitability for simultaneous pretreatments of batches of samples,and the higher extraction efficiency.It was successfully applied to the analysis of amphetamines in real human urine samples.

应用顶空-固相微萃取结合气相色谱-质谱联用技术分析传统锦州虾酱中挥发性物质

传统锦州虾酱是以白虾和乌虾为原料,在高盐条件下经长时间发酵形成海产风味食品。采用HPSPME/GC-MS结合保留指数方法分析虾酱中的挥发性物质,并对萃取条件进行优化。从DVB/PDMS、CAR/PDMS和DVB/CAR/PDMS筛选出最佳萃取头,同时采用正交试验优化SPME参数条件,确定适宜萃取条件为75μm CAR/PDMS萃取头,样品质量为5.0 g,萃取温度为70℃,萃取时间为50 min。对虾酱的风味物质分析得到44种挥发性物质,分别为醛类、酮类、酯类、酸类、酚类、烷烃类、吡嗪类和其他化合物。其中白虾虾酱主要呈香物质是醛类、吡嗪类和酚类等低阈值化合物,3-甲硫基丙醛、四甲基吡嗪和吲哚可能是白虾虾酱有别于乌虾虾酱的特有风味物质。乌虾虾酱主要呈香物质是醛类、酯类、酸类和酚类等低阈值化合物,酸类化合物是乌虾虾酱有别于白虾虾酱特有的风味物质,酯类化合物也可能是乌虾虾酱中风味物质的增味剂。

大鼠尿液中硝基安定代谢物的GC-MS检验

The metabolites and metabolic passways of nitrazepam in rat were confirmed.Wistar rats were feed a pill of nitrazepam,24 h urine reactions were collected.After β-Glucuronidase hydrolysis of the urine samples,the fractions were extracted by Oasis HLB3cc solid-phase column and analyzed by gas chromatography-mass spectrometry with DB-35 MS column.7-Acetylaminonitrazepam,7-aminonitrazepam and 2-amino-5-nitrophenylphenylmethanone were identified as nitrazepam metabolites.The results suggested that two metabolic passways for nitrazepam may be operative in rat.The first passway leads to the corresponding 7-aminonimetazepam in which the amino group is subsequently acetylated.The second passway is open the parent compounds rings to 2-amino-5-nitrophenylphenylmethanone.Nitrazepam was metabolized quickly in rats and 7-acetylaminonitrazepam were the main metabolites in urine.

林芝松口蘑与红菇蜡伞子实体香气成分比较

研究采用顶空固相微萃取技术联合气质联用技术分别对松口蘑和红菇蜡伞子实体香气成分进行分析测定和比较分析,以期建立准确、快速、高效的鉴别方法。结果显示,松口蘑检测到74种香气成分,红菇蜡伞检测到72种香气成分,松口蘑相较红菇蜡伞检测到特有的香气成分14种,包括乙醛、庚醛等6种醛类,2(5H)-呋喃酮1种酮类,3-苯丙醇1种醇类,正己酸乙酯、丙位戊内酯2种酯类,萜品烯和异松油烯等4个烯烃类;红菇蜡伞相较松口蘑,检测到特有的香气成分16种,包括2-丁基-2-辛烯醛1种醛类,3-羟基-2-丁酮、甲基庚烯酮等4种酮类,丁醇等5种醇类,(1-羟基-2,4,4-三甲基戊-3-基) 2-甲基丙酸酯1种酯类,异丁酸、丁酸等3种羧酸类,邻甲酚1种酚类,乙二醇单丁醚1种醚类,N-甲基吡咯烷酮1种含氮化合物。经过主成分分析,得到红菇蜡伞中的主要特征性香气成分为:己醛、3-羟基-2-丁酮、3-辛烯酮、2-甲烯基丁内酯、异戊酸;松口蘑中为:异戊醛、庚醛、壬醛、2,5,2-三甲基吡嗪、2,6,2-三甲基吡嗪。同时对松口蘑与红菇蜡伞干品挥发性香气成分相对含量对比发现,松口蘑主要香气成分含量关系为醛类>烯烃类>醇类>酯类,红菇蜡伞主要香气成分含量关系为醛类>醇类>烯烃类>酯类。通过松口蘑与红菇蜡伞子实体干品香气成分的比较分析可为市售的2种产品的快速检验鉴别奠定理论基础。

羊奶粉贮藏过程中挥发性成分的分析

采用顶空固相微萃取结合气质联用(headspace-solid phase microextraction coupled with gas chromatography-mass spectrometry,SPME-GC/MS)技术,对常温贮存下羊奶粉中挥发性成分进行提取与分析。在常温贮存1年的羊奶粉中,共检出41种挥发性成分。其中酸类成分最多,共13种,其次是酯类、烃类、醇类和醛酮类,分别为6、4、4和3种。羊奶粉的主体挥发性成分组成是丁酸、己酸、庚酸、辛酸、4-甲基辛酸、癸酸、月桂酸、邻苯二甲酸二甲酯、辛酸乙酯、十五烷、苯甲醛、甘菊环、己内酰胺,己酸、辛酸、4-甲基辛酸和癸酸在贮存6个月之后含量有明显增加趋势。在整个贮存期间,对羊奶粉膻味有较大影响的酸类物质有己酸、辛酸、4-甲基辛酸和癸酸,尤其是4-甲基辛酸,由于其较低阈值,成为最主要的羊膳物质,并且随着贮存时间的增加,酸类、酯类含量逐渐增加。

烤制时间对中式烤五花肉挥发性风味物质的影响

以猪五花肉为研究对象,利用万能蒸烤箱,研究恒定温度160℃条件下,不同烤制时间(5,10,15,20,25 min)对中式烤五花肉挥发性物质的影响。运用顶空固相微萃取(solid-phase microextraction,SPME)和气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)联用仪进行分析和鉴定,研究结果表明,中式烤五花肉在烤制时间下共鉴定出40种挥发性风味物质,其中醛类化合物7种、酯类化合物4种、醇类化合物8种、烃类化合物14种、其他化合物7种。从不同时间段来看,中式烤五花肉在烤制过程中,随着烤制时间的变化,在烤制25 min的条件下产生的挥发性物质数量最多。

福建姜黄挥发油化学成分的HS-SPME-GC-MS分析

采用水蒸气蒸馏法提取福建姜黄挥发油,应用顶空固相微萃取进样结合气相色谱-串联质谱联用技术(HS-SPME-GC-MS)分析姜黄挥发油的化学成分。结果表明:姜黄挥发油含有量为7.2%(mL/g),从姜黄挥发油中共分出62个色谱峰,初步鉴定出了其中的51种化学成分,占总挥发油总量的98.41%。在鉴定的化合物中,主要为单萜类化合物和倍半萜类化合物,其中新发现一种主要成分为β-柏木烯,相对含量占比高达26.58%,这可作为福建姜黄挥发油的特征成分和主要品质指标。本研究结果将为福建姜黄植物药材的品质评价提供科学依据。

Time-dependent categorization of volatile aroma compound formation in stewed Chinese spicy beef using electron nose profile coupled with thermal desorption GC–MS detection

In the present study,flavor profiles of Chinese spiced beef in the cooking process were comparatively analyzed by electronic nose,gas chromatography–mass spectrometry(GC–MS)with a thermal desorption system(TDS),and solid-phase microextraction(SPME).A total of 82 volatile compounds were identified,and 3-methyl-butanal,pentanal,hexanal,-xylene,heptanal,limonene,terpinene,octanal,linalool,4-terpinenol,-terpineol,and(E)-anethole were identified as the characteristic flavor compounds in Chinese spiced beef.Variation in the content of volatile components produced by different cooking processes was observed.In general,a cooking time of 4 h resulted in optimal flavor quality and stability.Results indicated that the electronic nose could profile and rapidly distinguish variation among different cooking time.The volatile profiling by TDS-GC–MS and responses from the electronic nose,in combination with multivariate statistical analysis,are a promising tool for control the cooking process of spiced beef.

Differential volatile organic compounds in royal jelly associated with different nectar plants

The aim of this work was to distinguish volatile organic compound（VOC） profiles of royal jelly（RJ） from different nectar plants. Headspace solid-phase microextraction（HS-SPME） was used to extract VOCs from raw RJ harvested from 10 nectar plants in flowering seasons. Qualitative and semi-quantitative analysis of VOCs extracts were performed by gas chromatography-mass spectrometry（GC-MS）. Results showed that VOC profiles of RJ from the samples were rich in acid, ester and aldehyde compound classes, however, contents of them were differential, exemplified by the data from acetic acid, benzoic acid methyl ester, hexanoic acid and octanoic acid. As a conclusion, these four VOCs can be used for distinguishing RJ harvested in the seasons of different nectar plants.

Selection of Yeast Strains Containing β-Glucosidase for Improving Wine Aroma

Aroma is an important component for characteristic of wine. β-glucosidase is an enzyme for enhancing wine aroma during fermentation and aging. The aim of this study was to evaluate β-glucosidase activities from 17 yeast strains. It was found that strain 71 B-1122 exhibited highest activity of β-glucosidase. The purified enzyme of this strain was characterized. The purified enzyme was added in Muscat must before wine making process. The must and wine were determined for volatile compounds by headspace-SPME/GC-MS and found that the hexyl acetate, linalool, phenethyl, nerol and geraniol compounds were significantly increased after treated with the enzyme. Sensory evaluation of the combined alcoholic fermentation and flavour enrichment of Muscat juice by adding of purified β-glucosidase enzyme showed well oenological properties especially aroma. Therefore, in producing wine, yeast strain selection and addition of β-glucosidase enzyme should be considered because they were important factors affecting wine aroma.

Analyses of BioVOCs variation related to vegetation predominance in the Natural Park of Ampezzo Dolomites, UNESCO world heritage area of Dolomites

The determination of emitted Biogenic Volatile Compounds （BioVOCs） profile via Field Air Analysis （FAA） - Solid Phase Micro Extraction （75μm Carboxen/PDMS portable field sampler） was performed using GC-MS. The six sampling sites located in the Natural Park of Ampezzo Dolomites, part of the UNESCO＇s World Heritage List, are characterized by different predominating vegetation. The ubiquitous compound hexanal was chosen as internal standard, in order to compare the amounts of the different compound in the different sites. The main terpenes identified were α-pinene, 13-pinene, 6-3-carene and d-limonene, while 1,8 cineole was the highest abundant oxygenated terpene. In the site next the＇national road a higher amount of benzene derivatives （ben- zene, toluene, o-xylene, p-xylene and ethylbenzene） were observed. In the site relatively close to the road a marked decrease of benzene deriva- tives was observed. In the sites close to conifers （i.e. Fir, Pine and Larch） the terpenic content observed was higher than in the site close to the mixed forest （mainly large-leaf and some conifers）. Some terpenes were observed also in the high-quote meadow site, although of lower abun- dance than in the other sites. The highest abundance of terpenes was ob- served in the Pinus cerebra （Swiss Pine） site.