Gas chromatography-mass spectrometry determination of 3-mercaptohexan-1-ol and 3-mercaptohexyl acetate in wine: a comparison of headspace solid phase microextraction and solid phase extraction methods

A gas chromatography-mass spectrometry method was established using headspace solid phase microextraction (HS-SPME) as the sampling procedure to analyse 3-mercaptohexan-1-ol (3-MH) and 3-mercaptohexyl acetate (3-MHA), two molecules with a tropical fruit aroma, in wine at trace level. This method offers important advantages, as it neither requires time-consuming sample preparation nor uses dangerous organic compounds, thus making control of wine aroma easier and suitable for routine analysis. As a comparison, a solid phase extraction (SPE) method, already described elsewhere for aroma analysis, was applied to quantify these analytes, extending this exhaustive enrichment to two important thiols. Detection limits for both the approaches were close to the sensory threshold value, resulting lower for the HS-SPME procedure and suitable for requirements in the oenological field. The application of the two proposed methods to 52 wines of different varieties gave similar results.     

Multivariate analysis of the volatile components in tobacco based on infrared‐assisted extraction coupled to headspace solid‐phase microextraction and gas chromatography‐mass spectrometry

A novel infrared‐assisted extraction coupled to headspace solid‐phase microextraction followed by gas chromatography with mass spectrometry method has been developed for the rapid determination of the volatile components in tobacco. The optimal extraction conditions for maximizing the extraction efficiency were as follows: 65 μm polydimethylsiloxane‐divinylbenzene fiber, extraction time of 20 min, infrared power of 175 W, and distance between the infrared lamp and the headspace vial of 2 cm. Under the optimum conditions, 50 components were found to exist in all ten tobacco samples from different geographical origins. Compared with conventional water‐bath heating and nonheating extraction methods, the extraction efficiency of infrared‐assisted extraction was greatly improved. Furthermore, multivariate analysis including principal component analysis, hierarchical cluster analysis, and similarity analysis were performed to evaluate the chemical information of these samples and divided them into three classifications, including rich, moderate, and fresh flavors. The above‐mentioned classification results were consistent with the sensory evaluation, which was pivotal and meaningful for tobacco discrimination. As a simple, fast, cost‐effective, and highly efficient method, the infrared‐assisted extraction coupled to headspace solid‐phase microextraction technique is powerful and promising for distinguishing the geographical origins of the tobacco samples coupled to suitable chemometrics.     

Polypyrrole modified stainless steel frits for on-line micro solid phase extraction of ochratoxin A

Polypyrrole (PPy) was electrochemically synthesized on stainless steel frits as a sorbent for the micro solid phase extraction (SPE) of ochratoxin A (OTA). Using 20 l of standard solution under a fast flow rate of 0.5 ml/min, 80% recovery of OTA was achieved in the concentration range from 0.1–10 pg/l. This good recovery was achieved within a short residence time of 1.2 s. A binding capacity of 1 ng OTA was estimated for each PPy-modified frit, or 2 ng OTA for two frits in series. The bound OTA could be pulsed eluted (PE) with 20 l of 1% triethylamine in acetonitrile. On-line coupling of this PPy-on-a-frit and PE technique to high performance liquid chromatography (HPLC) was straightforward. On-line SPE-PE-HPLC results clearly demonstrated the capability of PPy-on-a-frit to bind OTA in the presence of red wine, beer, and orange juice components.     

Rapid determination of the volatile components in tobacco by ultrasound‐microwave synergistic extraction coupled to headspace solid‐phase microextraction with gas chromatography‐mass spectrometry

An ultrasound‐microwave synergistic extraction coupled to headspace solid‐phase microextraction was first employed to determine the volatile components in tobacco samples. The method combined the advantages of ultrasound, microwave, and headspace solid‐phase microextraction. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, several experimental parameters, such as fiber type, ultrasound power, and irradiation time, were optimized to improve sampling efficiency. Under the optimal conditions, there were 37, 36, 34, and 36 components identified in tobacco from Guizhou, Hunan, Yunnan, and Zimbabwe, respectively, including esters, heterocycles, alkanes, ketones, terpenoids, acids, phenols, and alcohols. The compound types were roughly the same while the contents were varied from different origins due to the disparity of their growing conditions, such as soil, water, and climate. In addition, the ultrasound‐microwave synergistic extraction coupled to headspace solid‐phase microextraction method was compared with the microwave‐assisted extraction coupled to headspace solid‐phase microextraction and headspace solid‐phase microextraction methods. More types of volatile components were obtained by using the ultrasound‐microwave synergistic extraction coupled to headspace solid‐phase microextraction method, moreover, the contents were high. The results indicated that the ultrasound‐microwave synergistic extraction coupled to headspace solid‐phase microextraction technique was a simple, time‐saving and highly efficient approach, which was especially suitable for analysis of the volatile components in tobacco.     

Comparison of tetraethylborate and tetraphenylborate for selenite determination in human urine by gas chromatography mass spectrometry, after headspace solid phase microextraction

Two different derivatizing reagents were tested for the development of a fast and sensitive method for the determination of selenites (Se^IV) in human urine. The reagents were sodium tetraethylborate (NaBEt₄) and tetraphenylborate (NaBPh₄), respectively, and the procedure is based on in situ derivatization of selenites in aqueous medium. Selenite ions are converted to diethylselenide (DESe) or diphenylselenide (DPhSe) and subsequently collected from the headspace by solid phase microextraction using a silica fiber coated with polydimethylsiloxane (HS-SPME). Finally, they are quantitated by GC/MS in SIM mode. Ethylation over phenylation was proved preferable for the headspace extraction because of the higher volatility of the diethyl-derivative of selenites. The optimization of the HS-SPME conditions was performed both in aqueous and urinary solutions. Under the optimum conditions for HS-SPME, the gas chromatographic conditions were also optimized. Between the two alkylation reagents tetraethylborate was proved more efficient and the quantitation was satisfactory. Aqueous certified reference materials were analyzed to evaluate the accuracy of the method. The precision of the method was 4.2% and the calculated detection limit was 0.05 μg L⁻¹ for human urine.     

Determination of nine volatile N‐nitrosamines in tobacco and smokeless tobacco products by dispersive solid‐phase extraction with gas chromatography and tandem mass spectrometry

A method was developed for the determination of nine volatile N‐nitrosamines in tobacco and smokeless tobacco products. The targets are N‐nitrosodimethylamine, N‐nitrosopyrrolidine, N‐nitrosopiperidine, N‐nitrosomorpholine, N‐nitrosoethylmethylamine, N‐nitrosodiethylamine, N‐nitrosodipropylamine, N‐nitrosobuylmethylmine, and N‐nitrosodibutylamine. The samples were treated by dispersive solid‐phase extraction using 1 g of primary secondary amine and 0.5 g of carbon and then analyzed by gas chromatography with tandem mass spectrometry with an electron impact ion source. The recoveries for the targets ranged from 84 to 118%, with <16% relative standard deviations at three spiking levels of 0.5, 1.25, and 2.5 ng/g. The limits of detection ranged from 0.03 to 0.15 ng/g. With the use of the proposed method, we detected the presence of six nitrosamines in the range of 0.4–30.7 ng/g. The study demonstrated that the method could be used as a rapid, convenient, and high‐throughput method for N‐nitrosamines analysis in tobacco matrix.     

Advanced analytical techniques for the extraction and characterization of plant‐derived essential oils by gas chromatography with mass spectrometry

In recent years, essential oils have received a growing interest because of the positive health effects of their novel characteristics such as antibacterial, antifungal, and antioxidant activities. For the extraction of plant‐derived essential oils, there is the need of advanced analytical techniques and innovative methodologies. An exhaustive study of hydrodistillation, supercritical fluid extraction, ultrasound‐ and microwave‐assisted extraction, solid‐phase microextraction, pressurized liquid extraction, pressurized hot water extraction, liquid–liquid extraction, liquid‐phase microextraction, matrix solid‐phase dispersion, and gas chromatography (one‐ and two‐dimensional) hyphenated with mass spectrometry for the extraction through various plant species and analysis of essential oils has been provided in this review. Essential oils are composed of mainly terpenes and terpenoids with low‐molecular‐weight aromatic and aliphatic constituents that are particularly important for public health.     

顶空固相微萃取-气相色谱-质谱联用快速分析八角茴香中风味物质

采用顶空固相微萃取与气相色谱-质谱联用技术,对八角茴香中风味物质进行了分析。选用自制聚丙烯酸树脂涂层,对样品量、萃取时间、萃取温度、解吸时间等参数进行了优化,结果表明0．10g样品在60℃水浴中顶空萃取40min,250℃下解吸2min达到最佳条件。比较了顶空固相微萃取与传统水蒸气蒸馏两种前处理方法,分析结果非常相似。该方法可用于快速分析八角茴香中的风味物质。     

Rapid determination of 95 pesticides in soybean oil using liquid-liquid extraction followed by centrifugation, freezing and dispersive solid phase extraction as cleanup steps and gas chromatography with mass spectrometric detection

A multi-residue method using liquid-liquid extraction (LLE) followed by centrifugation, freezing and dispersive solid phase extraction (dispersive SPE) as clean up steps and gas chromatography with mass spectrometric detection has been developed for the determination of trace levels of 95 pesticides in soybean oil. LLE has been optimized to extract these pesticide residues from soybean oil by studying the effect of different partitions between (i) acetonitrile (MeCN) saturated with petroleum ether and a soybean oil solution dissolved in petroleum ether saturated with MeCN, (ii) partition between MeCN and a soybean oil solution dissolved in petroleum ether saturated with MeCN, (iii) partition between MeCN and a soybean oil solution dissolved in petroleum ether, (iv) partition between MeCN saturated with n-hexane and a soybean oil solution dissolved in n-hexane saturated with MeCN, (v) partition between MeCN and a soybean oil solution, (vi) partition between MeCN and a soybean oil solution dissolved in n-hexane and (vii) partition between MeCN and a soybean oil solution dissolved in mixture of acetone and n-hexane (3:2) to the highest recovery yield of pesticides and the lowest co-extract fat residue in the final extract. Experiments were carried out in order to study the efficiency of using centrifugation and freezing steps as well as the used of primary secondary amine (PSA), florisil, graphite carbon black (GCB) and C18 for dispersive SPE on clean up stages to minimize the co-extract fat. The recoveries obtained ranged from 80 to 114% and the relative standard deviation (RSDs) from 2 to 14% for spiking levels of 0.040, 0.080 and 0.160 mg kg^− 1. The limits of quantification (LOQs) of almost all compounds were below the maximum residue limits (MRLs) established by the Korean legislations for soybean oil.     

Analysis of volatile organic compounds in pleural effusions by headspace solid‐phase microextraction coupled with cryotrap gas chromatography and mass spectrometry

Headspace solid‐phase microextraction coupled with cryotrap gas chromatography and mass spectrometry was applied to the analysis of volatile organic compounds in pleural effusions. The highly volatile organic compounds were separated successfully with high sensitivity by the employment of a cryotrap device, with the construction of a cold column head by freezing a segment of metal capillary with liquid nitrogen. A total of 76 volatile organic compounds were identified in 50 pleural effusion samples (20 malignant effusions and 30 benign effusions). Among them, 34 more volatile organic compounds were detected with the retention time less than 8 min, by comparing with the normal headspace solid‐phase microextraction coupled with gas chromatography and mass spectrometry method. Furthermore, 24 volatile organic compounds with high occurrence frequency in pleural effusion samples, 18 of which with the retention time less than 8 min, were selected for the comparative analysis. The results of average peak area comparison and box‐plot analysis showed that except for cyclohexanone, 2‐ethyl‐1‐hexanol, and tetramethylbenzene, which have been reported as potential cancer biomarkers, cyclohexanol, dichloromethane, ethyl acetate, n‐heptane, ethylbenzene, and xylene also had differential expression between malignant and benign effusions. Therefore, the proposed approach was valuable for the comprehensive characterization of volatile organic compounds in pleural effusions.     

Self‐assembly of poly(ionic liquid) functionalized mesoporous magnetic microspheres for the solid‐phase extraction of preservatives from milk samples

In this work, a novel, rapid, and simple analytical method was proposed for the detection of parabens in milk sample by gas chromatography coupled with mass spectrometry. At the same time, milk sample was pretreated by magnetic solid phase extraction, which detected up to five parabens. A series of important parameters of magnetic solid phase extraction were investigated and optimized, such as pH value of loading buffer, amount of material, adsorption time, ionic strength, eluting solvents, and eluting time. Under the optimized conditions, the corresponding values were more than 0.9991, limits of detection and the limit of quantification were 0.1 and 0.5 ng/mL, respectively. In addition, the recoveries were achieved in range of 95–105%, the liner range were within 0.1–600 ng/mL, and the relative standard deviations were even lower than 5%.     

Resorcinol–formaldehyde xerogel as a micro‐solid‐phase extraction sorbent for the determination of herbicides in aquatic environmental samples

In this study, organic aerogels were synthesized by the sol–gel polycondensation of mixed cresol with formaldehyde in a slightly basic aqueous solution. Carbon aerogels and xerogels are generated by pyrolysis of organic aerogels. The novel sol–gel‐based micro‐solid‐phase extraction sorbent, resorcinol–formaldehyde xerogel, was employed for preconcentration of some selected herbicides. Three herbicides of the aryloxyphenoxypropionate group, clodinafop‐propargyl, haloxyfop‐etotyl, and fenoxaprop‐P‐ethyl, were extracted from aqueous samples by micro‐solid‐phase extraction and subsequently determined by gas chromatography with mass spectrometry. The effect of different parameters influencing the extraction efficiency of these herbicides including sample flow rate, sample volume, and extraction time were investigated and optimized. Under optimum conditions, linear calibration curves in the range of 0.10–500 ng/L with R² > 0.99 were obtained. The relative standard deviation at 50 μg/L concentration level was lower than 10% (n = 5) and detection limits were between 0.05 and 0.20 μg/L. The proposed method was successfully applied to the sampling and extraction of herbicides from Zayanderood and paddy water samples.     

Supercritical fluid extraction for identification and determination of volatile metabolites from Angelica dahurica by GC-MS

The volatile components of Angelica dahurica were obtained by supercritical fluid extraction (SFE) method. These oils obtained were analyzed by GC-MS (identification and determination of metabolites). The compounds were identified according to their retention indices and mass spectra (electron impact (EI), 70 eV). The effects of different parameters, such as pressure, temperature, flow rate of CO(2), and the amount of modifier, on the SFE of A. dahurica oil were investigated. A total of 50 compounds of SFE extracts were identified. Phellopterin (PO), isoimperatorin (IO), imperatorin (IM), alloimperatorin (AM), byakangelicin, isooxypeucedanin, and pimpinellin were the major coumarin compounds identified in A. dahurica SFE extracts. The quantitations of PO, IO, IM, and AM were then accomplished. The calibration curves showed good linearity (R(2) >0.99) in the concentration ranges tested. The recoveries were higher than 85%, with RSDs less than 10%. The GC-MS method was successfully validated and applied to the quantitation of A. dahurica.     

Electrospun zeolitic imidazolate framework-8/poly(lactic acid) nanofibers for pipette-tip micro-solid phase extraction of carbamate insecticides from environmental samples

In the present study, electrospun zeolitic imidazolate framework-8/poly(lactic acid) nanofibers were successfully synthesized and characterized as a potential nanosorbent for the pipette-tip micro-solid phase extraction of chlorpropham, pirimicarb, carbaryl, and methiocarb carbamate insecticides from environmental water samples. The extraction procedure was followed by gas chromatography/mass spectrometry separation and determination of the target analytes. All the effective parameters of the extraction procedure were optimized through the one variable at-a-time method. Thanks to the very simple extraction procedure as well as the application of electrospun nanofibers with high surface area, the four analytes were efficiently extracted with as lowest extraction times as practicable. Under the optimal conditions, the calibration plots of the analytes were obtained within broad linear dynamic ranges of 0.5 – 150 ng mL^?1 for chlorpropham and pirimicarb plus 1.0 – 175 ng mL^?1 for carbaryl and methiocarb, respectively. Besides, limits of detection as low as 0.2 and 0.15 ng mL^?1 for chlorpropham and pirimicarb, respectively, as well as 0.5 ng mL^?1 for carbaryl and methiocarb indicate the favorable sensitivity of the analytical procedure. The applicability of the developed method was evaluated by quantitative determination of the target analytes in four different environmental water samples. Relative recoveries higher than 88.0% shows the acceptable accuracy of the method in the quantitative determination of the four carbamate insecticides.     

Identification of volatile components in Angelica species using supercritical-CO2 fluid extraction and solid phase microextraction coupled to gas chromatography-mass spectrometry

As a part of our search for environmentally friendly solvents to extract the active components of medicinal plants, two sampling techniques, supercritical fluid extraction (SFE) using CO(2) and solid-phase microextraction (SPME) were compared for their efficacy in the analysis of volatiles rhizome components emitted from the medicinal herbs Angelica gigas NAKAI (Korean danggui), Angelica sinensis (Chinese danggui), and Angelica acutiloba (Japanese danggui). A total of 54 compounds released from all of these varieties of Angelica rhizomes were separated and identified by gas chromatography-mass spectrometry (GC-MS). The composition of supercritical extracts from these plants was very different from the solid-phase microextraction products. More compounds were detected by SPME-GC-MS (41) than by SFE-GC-MS (17). The results of these analyses suggest that SFE may be useful for detecting the main components, decursinol angelate and decursin in Korean danggui, and butylidene dihydro-phthalide in both Chinese and Japanese danggui, whereas the results for SPME did not. The SFE method required specialized instrumentation, required little time to prepare the sample, and had a small sample size and no organic solvent. In sum, these results suggest that SFE is useful for extracting the volatile main components of danggui cultivars. Its simplicity, low cost and speed may allow SPME to increase the recovery of volatile components in general without disturbing the main components of the plant.     

低温冷冻及分散固相萃取净化-超高效液相色谱-串联质谱法测定植物油中104种农药残留

建立了适用于植物油中104种农药残留的检测方法。通过液液萃取(LLE)提取目标化合物,再借助离心、冷冻和分散固相萃取(D-SPE)净化手段,依托超高效液相色谱-串联质谱测定。以回收率和共提取物为衡量指标,着重优化了6种提取方式、不同冷冻时间及PSA(primary secondary amine)、GCB(graphite carbon black)和C18这3种不同固相萃取填料不同组合的效果。在0.01、0.02和0.05 mg/kg水平的平均添加回收率为55%~121%, RSD为0.47%~19.2%, 80%的目标物的定量限可达到1 μg/kg,低于我国相关标准限量,能够满足多种农药残留同时分析的要求。该方法步骤简便、可靠、稳定,可应用于进口植物油中多种农药残留的快速检测与确证的日常检测工作中,具有一定的推广价值。     

On-line solid phase extraction LC-MS/MS analysis of pharmaceutical indicators in water: A green alternative to conventional methods

A method using automated on-line solid phase extraction (SPE) directly coupled to liquid chromatography/tandem mass spectrometry (LC-MS/MS) has been developed for the analysis of six pharmaceuticals by isotope dilution. These selected pharmaceuticals were chosen as representative indicator compounds and were used to evaluate the performance of the on-line SPE method in four distinct water matrices. Method reporting limits (MRLs) ranged from 10 to 25 ng/L, based on a 1 mL extraction volume. Matrix spike recoveries ranged from 88 to 118% for all matrices investigated, including finished drinking water, surface water, wastewater effluent and septic tank influent. Precision tests were performed at 50 and 1000 ng/L with relative standard deviations (RSDs) between 1.3 and 5.7%. A variety of samples were also extracted using a traditional off-line automated SPE method for comparison. Results for both extraction methods were in good agreement; however, on-line SPE used approximately 98% less solvent and less time. On-line SPE coupled to LC-MS/MS analysis for selected indicators offers an alternative, more environmentally friendly, method for pharmaceutical analysis in water by saving time and costs while reducing hazardous waste and potential environmental pollution as compared with off-line SPE methods.     

Determination of fungicides in wine by mixed-mode solid phase extraction and liquid chromatography coupled to tandem mass spectrometry

A novel procedure for the determination of nine selected fungicides (metalaxyl-M, azoxystrobin, myclobutanil, flusilazole, penconazole, tebuconazole, propiconazole, diniconazole and difenoconazole) in wine samples is presented. Sample enrichment and purification is simultaneously performed using mixed-mode, anion exchange and reversed-phase, OASIS MAX solid-phase extraction (SPE) cartridges. Analytes were determined by liquid chromatography coupled to tandem mass spectrometry using atmospheric pressure electrospray ionization (LC-ESI-MS/MS). Parameters affecting the chromatographic determination and the extraction-purification processes were thoroughly investigated. Under optimized conditions, 10 mL of wine were firstly diluted 1:1 with ultrapure water and then passed through the mixed-mode SPE cartridge at a flow of ca. 5 mLmin(-1). After a washing step with 5 mL of an aqueous NH(4)OH solution (5%, w:v), analytes were recovered with just 1 mL of methanol and injected in the LC-MS/MS system without any additional purification. The selective extraction process avoided significant changes in the ionization efficiency for red and white wine extracts in comparison with pure standards in methanol. Performance of the method was good in terms of precision (RSDs<11%) and accuracy (absolute recoveries>72%, determined against pure standards in methanol) reporting method LOQs in the range of 0.01-0.79 ngmL(-1) for target compounds, which are far below the EU maxima residue levels (MRLs) for fungicides in vinification grapes and wine. Several commercial wines from different geographic areas in Spain were analyzed. In most samples, metalaxyl-M and azoxystrobin were found at concentrations up to several ngmL(-1).     

Electrospun terpolymeric nanofiber membrane for micro solid‐phase extraction of diazinon and chlorpyrifos from aqueous samples

The present study deals with the synthesis and electrospining of a new terpolymer nanofiber in order to determine the amount of diazinon and chlorpyrifos in water and fruit juice samples. The synthesized terpolymer and the prepared nanofiber were characterized using ¹H NMR spectroscopy, FTIR spectroscopy, scanning electron microscopy, and gel permeation chromatography. The performance of terpolymer nanofiber, prepared as a sorbent for micro solid phase extraction was investigated for the extraction of diazinon and chlorpyrifos from aquaeous media. Then, the target analytes were desorbed from the coating with an organic solvent and analyzed by gas chromatography with flame ionization detector. Extraction efficiencies were significant (>90%) under the optimum condition. The proposed method also demonstrated good linear dynamic ranges for diazinon and chlorpyrifos (3–250 and 5–200 µg/L), and low limit of detections (0.5 and 0.7 µg/L) respectively. Moreover, under optimum condition for extraction of diazinon and chlorpyrifos, square of correlation coefficients (R²) of 0.9978 and 0.9953 and relative standard deviations of 4.6 and 5.1% were achieved, respectively. The recoveries for diazinon and chlorpyrifos were in the range of 85–97%.     

固相萃取-气相色谱-串联质谱法检测水中18种酚类化合物

当前水中酚类化合物种类不清、危害不明,多种酚类化合物的同时检测方法不成熟,因此建立水中多种酚类化合物同时检测的方法具有重要现实意义。该研究建立了固相萃取结合气相色谱-串联质谱同时检测水中18种酚类化合物的分析方法。实验选择超纯水为空白样品,采用固相萃取技术富集、提取水中的酚类化合物,同时对水样初始pH值、洗脱液的种类、洗脱液的用量等条件进行优化,从而确定出最优的前处理方法,最后利用气相色谱-串联质谱法对不同种类的酚类化合物同时进行定量检测。实验结果表明,在初始水样pH值为3.0、不衍生等条件下,使用10 mL乙酸乙酯洗脱,控制洗脱速度为1 mL/min,经固相柱富集净化,氮吹浓缩后,用气相色谱-质谱仪(EI源)测定,选择离子模式监测,外标法定量。结果表明,以3倍信噪比结合浓度外推法确定方法检出限,为0.04～0.6μg/L; 18种酚类化合物的加标回收率为51.7%～117.3%,相对标准偏差为3.1%～7.4%。应用建立的方法分别检测了河流湖泊水、生活用水、生产用水3大类6种不同的水质。检测结果表明,河流湖泊水中酚类化合物所含种类最多,含量最高。研究建立的方法不需要衍生,简化了前处理...