Headspace single-drop microextraction with in-drop derivatization for aldehyde analysis

A new technique, headspace single-drop microextraction (HS-SDME) with in-drop derivatization, was developed. Its feasibility was demonstrated by analysis of the model compounds, aldehydes in water. A hanging microliter drop of solvent containing the derivatization agent of O-2,3,4,5,6-(pentaflurobenzyl)hydroxylamine hydrochloride (PFBHA) was shown to be an excellent extraction, concentration, and derivatization medium for headspace analysis of aldehydes by GC-MS. Using the microdrop solvent with PFBHA, acetaldehyde, propanal, butanal, hexanal, and heptanal in water were headspace extracted and simultaneously derivatized. The formed oximes in the microdrop were analyzed by GC-MS. HS-SDME and in-drop derivatization parameters (extraction solvent, extraction temperature, extraction time, stirring rate microdrop volume, and the headspace volume) and the method validations (linearity, precision, detection limit, and recovery) were studied. Compared to liquid-liquid extraction and solid-phase microextraction, HS-SDME with in-drop derivatization is a simple, rapid, convenient, and inexpensive sample technique.     

Rapid determination of volatile constituents of Michelia alba flowers by gas chromatography-mass spectrometry with solid-phase microextraction

The volatile constituents of Michelia alba flowers, including fresh flowers, frozen flowers and withered flowers, were investigated by GC-MS. The volatiles in a simulated natural environment were sampled by solid-phase microextraction (SPME), with a 100 microm polydimethylsiloxane fiber at 25+/-5 degrees C for 4 h. The fibers were desorbed in a GC injection liner at 250 degrees C for 3 min. With headspace SPME-GC-MS analysis, 61 peaks were separated. The main compounds in headspace of fresh Michelia alba flowers included alpha-myrcene, (S)-limonene, (R)-fenchone, linalool, camphor, caryophyllene, germacrene D, etc., a greater number of compounds than for frozen flowers and withered flowers. At the same time, the biomarkers of fresh flowers were compared with the frozen flowers and withered flowers. In this study, headspace SPME-GC-MS afforded a simple and more sensitive sampling method for fresh Michelia alba flowers and other fresh flowers.     

Determination of organotin compounds in-water by headspace solid phase microextraction with gas chromatography-mass spectrometry

This investigation evaluates headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) to determine trace levels of organotins in water. The organotins were derivatized in situ with sodium tetraethylborate and adsorbed on a poly(dimethysiloxane) (PDMS)-coated fused silica fiber. The SPME experimental procedures to extract organotins in water were at pH 5, with extraction and derivatization simultaneously at 45 degrees C for 30 min in a 2% sodium tetraethylborate solution and a sample solution volume in the ratio of 1:1, and desorption in the splitless injection port of the GC at 260 degrees C for 2 min. Detection limits are determined to be in the low ng/L range. According to the analysis, the linearity range is from 10 to 10,000 ng/L with R.S.D. values below 12% except triphenyltin (24%). The proposed method was tested by analyzing surface seawater from the harbors on the Taiwanese coast for organotins residues. Some organotins studied were detected in the analyzed samples. Results of this study demonstrate the adequacy of the headspace SPME-GC-MS method for analyzing organotins in sea water samples.     

顶空固相微萃取-气相色谱-质谱联用测定香水中5种合成麝香

建立了香水中5种合成麝香的顶空固相微萃取-气相色谱-质谱联用分析方法。实验选用65 μm的聚二甲基硅氧烷-二乙烯基苯(PDMS-DVB)萃取纤维,在磁力搅拌600 r/min条件下,考察了萃取温度、平衡时间、萃取时间、解吸时间、进样口温度和盐效应6个方面对实验结果的影响。优化后的条件为: 10 mL顶空瓶中加入适量用水稀释过的样品,于60 ℃平衡3 min后,顶空萃取20 min,随即插入气相色谱进样口,于250 ℃解吸3 min进行定性、定量分析。5种合成麝香在0.05～1.00 μg/g范围内线性关系良好,检出限(LOD)为0.6～2.1 ng/g。空白样品在3个浓度加标水平下(0.05, 0.50, 1.00 μg/g)的回收率为82.0%～103.3%,相对标准偏差(RSD)为1.8%～9.4%。本方法简便、准确、快速、灵敏,适用于香水中合成麝香的分析检验工作。     

A simple, rapid and sensitive method for determination of aldehydes in human blood by gas chromatography/mass spectrometry and solid-phase microextraction with on-fiber derivatization

Aldehydes are considered potential markers for enhanced oxidative stress and have been proposed as a diagnostic measure of cancer status. Do to their volatility and activity, it is very difficult to accurately measure aldehydes in human blood. In the present work, gas chromatography/mass spectrometry (GC/MS) and solid-phase microextraction (SPME) with on-fiber derivatization was developed for determination of aldehydes in human blood. O-(2,3,4,5,6-Pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) in aqueous solution was first adsorbed by a SPME fiber, and then the aldehydes in blood samples were headspace extracted by the SPME fiber and rapidly derivatized with PFBHA on the SPME fiber. Finally, the oximes formed were desorbed and detected by GC/MS in electron ionization (EI) mode. Validation of the present method was carried out, and the method was applied to quantitative analysis of the aldehydes in lung cancer blood. The results demonstrated that GC/MS and SPME with on-fiber derivatization is a simple, rapid, sensitive and solvent-free method for the determination of aldehydes in human blood.     

Simple and sensitive analysis of nereistoxin and its metabolites in human serum using headspace solid-phase microextraction and gas chromatography-mass spectrometry

A simple method for the analysis of nereistoxin and its metabolites in human serum using headspace solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) is developed. A vial containing a serum sample, 5M sodium hydroxide, and benzylacetone (internal standard) is heated to 70 degrees C, and an SPME fiber is exposed for 30 min in the headspace of the vial. The compounds extracted by the fiber are desorbed by exposing the fiber in the injection port of the GC-MS. The calibration curves show linearity in the range of 0.05-5.0 micrograms/mL for nereistoxin and N-methyl-N-(2-methylthio-1-methylthiomethyl)ethylamine, 0.01-5.0 micrograms/mL for S,S'-dimethyl dihydronereistoxin, and 0.5-10 micrograms/mL for 2-methylthio-1-methylthiomethylethylamine in serum. No interferences are found, and the analysis time is 50 min for one sample. In addition, this proposed method is applied to a patient who attempted suicide by ingesting Padan 4R, a herbicide. Padan 4R contains 4% cartap hydrochloride, which is an analogue of nereistoxin. Nereistoxin and its metabolites are detected in the serum samples collected from the patient during hospitalization. The concentration ranges of nereistoxin in the serum are 0.09-2.69 micrograms/mL.     

Solid-phase microextraction for the determination of haloanisoles in wines and other alcoholic beverages using gas chromatography and atomic emission detection

A headspace solid-phase microextraction (HS-SPME) method for the determination of 12 haloanisoles in wine and spirit samples using gas chromatography with atomic emission detection (GC-AED) was developed. The different factors affecting the efficiency of the extraction were carefully optimized. The divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was the most suitable for preconcentrating the analytes from the headspace of the sample solution. Sample:water dilutions of 3:4 and 1:6 for wines and spirits, respectively, and the use of a mixed bromochloroanisole compound as internal standard allowed sample quantification against external standards prepared in the presence of 5% (v/v) ethanol. Detection limits ranged from 1.2 to 18.5ngL(-1), depending on the compound and the sample analyzed, with a fiber time exposure of 60min at 75 degrees C. The optimized method was successfully applied to different samples, and several of the studied haloanisoles were detected at concentration levels ranging from 10.3ngL(-1) to 1.14ngmL(-1).     

Determination of isophorone in food samples by solid-phase microextraction coupled with gas chromatography-mass spectrometry

A simple and sensitive method for the determination of isophorone in food samples was developed by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Isophorone was separated within 10 min by GC-MS using a DB-1 capillary column and detected with selective ion monitoring mode. The HS-SPME using a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber provided effective sample enrichment, and was carried out by fiber exposition at 60 degrees C for 45 min. The extracted isophorone was easily desorbed by fiber exposition in the injection port of a capillary GC-MS system, and carryover was not observed. Using this method, the calibration curve of isophorone was linear in the range 20-1000 pg/mL, with a correlation coefficient 0.9996 (n = 18), and the detection limit (S/N = 3) was 0.5 pg/mL. The HS-SPME/GC-MS method showed 25,000-fold higher sensitivity than the direct injection method (1 microL injection). The within-day and between-day precisions (relative standard deviations) at the concentration of 1 ng/mL isophorone were 3.9% and 6.1% (n=5), respectively. This method was successfully applied to the analysis of food samples without interference peaks. The recoveries of isophorone spiked into food sample were above 84% for a 50 or 500 pg/mL spiking concentration. The analytical results of the contents of isophorone in various food samples were presented.     

Rapid analysis of aldehydes by simultaneous microextraction and derivatization followed by GC-MS

Ultrasound-assisted dispersive liquid-liquid microextraction (UDLLME) and simultaneous derivatization followed by GC-MS was developed for the analysis of four aldehydes including acetaldehyde (ACE), propionaldehyde (PRO), butyraldehyde (BUT) and valeraldehyde (VAL) in water samples. In the proposed method, the aldehydes were derivatized with O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine (PFBHA) and extracted by UDLLME in aqueous solution simultaneously; finally, the derivatives were analyzed by GC-MS. The experimental parameters were investigated and the method validations were studied. The optimal conditions were: aqueous sample of 5 mL, PFBHA of 50 μL, 1.0 mL ethanol (disperser solvent) containing 20 μL chlorobenzene (extraction solvent), ultrasound time of 2 min and centrifuging time of 3 min at 6000 rpm. The proposed method provided satisfactory precision (RSD 1.8-10.2%), wide linear range (0.8-160 μg/L), good linearity (R(2) 0.9983-0.9993), good relative recovery (85-105%) and low limit of detection (0.16-0.23 μg/L). The proposed method was successfully applied for the analysis of aldehydes in water samples. The experimental results showed that the proposed method was a very simple, rapid, low-cost, sensitive and efficient analytical method for the determination of trace amount of aldehydes in water samples.     

Evaluation of solid-phase microextraction methods for determination of trace concentration aldehydes in aqueous solution

A method for trace analysis of a wide range of aldehydes (saturated/unsaturated aliphatic, aromatic aldehydes, including hydroxylated species, and dialdehydes) in an aqueous solution was optimized. An evaluation of three solid-phase microextraction (SPME) techniques (headspace, liquid-phase, and on-fiber derivatization) with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) aldehyde derivatization was performed focusing on the optimization of the main extraction parameters (temperature and time). The optimized method employed the liquid-phase SPME (D-L-SPME) of derivatized aldehydes at 80 degrees C for 30 min. Limits of detection (LODs) using this optimal method were in the range of 0.1-4.4 microg/L for the majority of aliphatic (saturated, unsaturated), aromatic aldehydes and dialdehydes. Formaldehyde LODs and those of some hydroxylated aromatic aldehydes were between 32 and 55 microg/L. Headspace SPME using an on-fiber derivatization generally showed a lower sensitivity and several compounds were not detected. Another technique, the optimized headspace SPME of aldehydes derivatized in aqueous solution, was not as sensitive as D-L-SPME for hydroxylated aromatic aldehydes. The developed method was used to analyze aqueous particulate matter extracts; this method achieved higher sensitivities than those obtained with US Environmental Protection Agency (EPA) Method 556.     

Flavour analysis of Greek white wine by solid-phase microextraction-capillary gas chromatography-mass spectrometry

Solid-phase microextraction (SPME) was optimised for the qualitative determination of the volatile flavour compounds responsible for the aroma of Greek Boutari wine. Several factors influencing the equilibrium of the aroma compounds between the sample and the SPME fiber were taken into account, including the extraction time, the extraction temperature, the sampling mode (headspace and direct immersion or liquid SPME), and the presence of salt. Four different SPME fibers were used in this study. namely poly(dimethylsiloxane) (PDMS), poly(acrylate), carbowax-divinylbenzene and divinylbenzene-carboxen on poly(dimethylsiloxane). The best results were obtained using the PDMS fiber during headspace extraction at 25 degrees C for 30 min after saturating the samples with salt. The optimised SPME method was then applied to investigate the qualitative aroma composition of three other Greek wines, namely Zitsa, Limnos and Filoni.     

固相微萃取-气相色谱/质谱分析栀子花的头香成分

 分别用固相微萃取和动态顶空法分离栀子鲜花的头香成分,用GC/MS技术分析鉴定,并用GC/MS总离子流色谱峰的峰面积进行归一化定量。在固相微萃取方法中,共鉴定了54种化学成分,占总峰面积的99.98%。主要成分(质量分数)依次为金合欢烯（64.86%）、罗勒烯（29.33%）、芳樟醇（2.74%）、惕各酸顺式叶醇酯（1.34%）和苯甲酸甲酯（0.25%）等。经与动态顶空法的分析结果比较发现,固相微萃取法不仅操作简便,而且具有较高的采样灵敏度,获得的化学成分的信息量多于动态顶空法。     

Development of a headspace solid phase microextraction-gas chromatography method for monitoring volatile compounds in extended time-course experiments of olive oil

A novel method for monitoring fibre performance and death, based on a Shewhart control plot, for use in headspace analysis by solid phase microextraction-gas chromatography (SPME-GC) is presented. The method is also demonstrated to be effective in standardising fibre response in extended time-course experiments, where several fibres may be required to complete a lengthy study. Extraction conditions that gave good total recovery and diversity of compounds, from olive oil headspace were found to be: 1 g oil sample in 10 mL vessel; exposure of DVB-CAR-PDMS, 50/30 μm fibre for 30 min at 40 °C; and desorption for 3 min at 250 °C. Calibration curves were constructed for 25 compounds commonly reported in olive oil headspace; with coefficients of determination (R²) ranging from 0.959 to 0.994 and limits of detection (LOD) from 0.01 to 0.59 μg/g. The method was applied to monitor the change in concentration of select C6 volatile compounds, which have implications in sensory quality - E-2-hexenal, hexanal, E-2-hexen-1-ol, hexanol - over a period of 12 months storage.     

Fast and sensitive method to determine chloroanisoles in cork using an internally cooled solid-phase microextraction fiber

A new generation of solid-phase microextraction (SPME) fiber, an internally cooled fiber (cold fiber with polydimethylsiloxane loading) that allows heating the sample matrix and simultaneously cooling the fiber coating, was used to determine 2,4-dichloroanisole, 2,6-dichloroanisole, 2,4,6-trichloroanisole and pentachloroanisole in cork. A comparison between the cold fiber and regular SPME fiber was performed. An automated headspace solid-phase microextraction (HS-SPME) using commercial fibers and an internally cooled SPME fiber (CF-HS-SPME) coupled to gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS) was used. The extraction conditions for both CF-HS-SPME and HS-SPME were optimized using full factorial design and Doehlert matrix. The best extraction conditions for CF-HS-SPME were obtained using 10 min of incubation time, 10 min of extraction time, and sample and fiber temperature of 130 and 10 degrees C, respectively. For HS-SPME, polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was used with 10 min of incubation time, 75 min of extraction time, 85 degrees C of sample temperature, 8 ml of water was added and agitated at 500 rpm. The quantification limits for the target compounds using CF-HS-SPME procedure were between 0.8 and 1.6 ng g(-1) of cork, while for HS-SPME were between 4 and 6 ng g(-1) of cork. Furthermore, the CF-HS-SPME procedure could be used as a non-destructive method after minor modification of the agitator for the autosampler.     

Impact of phase ratio, polydimethylsiloxane volume and size, and sampling temperature and time on headspace sorptive extraction recovery of some volatile compounds in the essential oil field

This study evaluates concentration capability of headspace sorptive extraction (HSSE) and the influence of sampling conditions on HSSE recovery of an analyte. A standard mixture in water of six high-to-medium volatility analytes (isobutyl methyl ketone, 3-hexanol, isoamyl acetate, 1,8-cineole, linalool and carvone) was used to sample the headspace by HSSE with stir bars coated with different polydimethylsiloxane (PDMS) volumes (20, 40, 55 and 110 microL, respectively), headspace vial volumes (8, 21.2, 40, 250 and 1000 mL), sampling temperatures (25, 50 and 75 degrees C) and sampling times (30, 60 and 120 min, and 4, 8 and 16 h). The concentration factors (CFs) of HSSE versus static headspace (S-HS) were also determined. Analytes sampled by the PDMS stir bars were recovered by thermal desorption (TDS) and analysed by capillary GC-MS. This study demonstrates how analyte recovery depends on its physico-chemical characteristics and affinity for PDMS (octanol-water partition coefficients), sampling temperatures (50 degrees C) and times (60 min), the volumes of headspace (40 mL) and of PDMS (in particular, for high volatility analytes). HSSE is also shown to be very effective for trace analysis. The HSSE CFs calculated versus S-HS with a 1000 mL headspace volumes at 25 degrees C during 4 h sampling ranged between 10(3) and 10(4) times for all analytes investigated while the limits of quantitation determined under the same conditions were in the nmol/L range.     

Development of an SPME-GC-MS/MS procedure for the monitoring of 2-phenoxyethanol in anaesthetised fish

2-Phenoxyethanol (ethylene glycol monophenyl ether, C(8)H(10)O(2)) is a promising anaesthetic agent used in fisheries and aquaculture. The aim of this study was to develop a fast and easy method to determine 2-phenoxyethanol residue levels in fish tissue and blood plasma, and, subsequently, to use the method to monitor the dynamics of 2-phenoxyethanol residues in fish treated with anaesthetic. We developed a new procedure that employs solid phase microextraction (SPME) of the target analyte from the sample headspace followed by gas chromatography-mass spectrometry (GC-MS). Both sample handling, aimed at maximum transfer of 2-phenoxyethanol into the headspace, and SPME-GC-MS conditions were carefully optimised. Using a divinylbenzene/Carboxen/polydimethylsiloxane (PDMS/CAR/DVB) fiber for 60 min sampling at 30 degrees C and an ion trap detector operated in MS/MS mode, we obtained detection (LOD) and quantification (LOQ) limits of 0.03 and 0.1 mg kg(-1) of sample, respectively. The method was linear in a range of 0.1-250 mg kg(-1) and, depending on the sample matrix and spiking level, a repeatability (expressed as relative standard deviation, R.S.D.) of between 3% and 11% was obtained.     

Rapid headspace solid-phase microextraction-gas chromatographic-time-of-flight mass spectrometric method for qualitative profiling of ice wine volatile fraction. I. Method development and optimization

An analytical method for the determination of volatile and semi-volatile compounds representing various chemical groups in ice wines was developed and optimized in the presented study. A combination of the fully automated solid-phase microextraction (SPME) sample preparation technique and gas chromatographic-mass spectrometric (GC-MS) system to perform the final chromatographic separation and identification of the analytes of interest was utilized. A time-of-flight mass spectrometric (TOF-MS) analyzer provided very rapid analysis of this relatively complex matrix. Full spectral information in the range of m/z 35-450 was collected across the short GC run (less than 5 min). Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS) 50/30 microm fiber performed best during the optimization experiments and it was used in the headspace SPME mode to isolate compounds from ice wine samples, consisting of 3 mL wine with 1g salt addition. After the sample incubation and extraction (both 5 min at 45 degrees C), analytes were thermally desorbed in the GC injector for 2 min (injector maintained at 260 degrees C) and transferred into the column. The MS data acquisition rate of 50 spectra/s was selected as optimal. The optimized analytical method did not exceed 20 min per sample, including both the isolation and pre-concentration of the analytes of interest, the final GC-TOF-MS analysis and the fiber bake-out. Both a linear temperature-programmed retention index (LTPRI) method using C(8)-C(20) alkanes loaded onto the fiber and a mass spectral library search were employed to identify the target compounds. The repeatability of the developed and optimized HS-SPME-GC-TOF-MS method for ice wine analysis, expressed as relative standard deviation (RSD, %, n=7), ranged from 3.2 to 9.0%.     

静态顶空气相色谱-质谱联用法快速测定海水中13种苯系物

建立了静态顶空萃取、气相色谱-质谱联用(HS-GC/MS)同时测定海水中常见的痕量13种苯系物(BTEX)方法。对影响分析效果的主要条件: 色谱柱类型、升温程序、顶空平衡温度、平衡时间以及气液体积比进行了详细的分析和优化。在优化条件下,该方法的线性相关系数大于0.999,线性范围为0.16～320 μg/L,检出限(按信噪比为3计)为0.019～0.033 μg/L;水样中3个加标水平(1.6、16和160 μg/L)的回收率为81.25%～103.73%,相对标准偏差(RSD, n=6)为0.3%～4.4%。将该方法应用于上海黄浦区海水样品中苯系物的测定,结果令人满意。该方法分析时间为12 min,操作简单快捷,灵敏度高,环境友好,定性、定量准确、可靠。     

Development of solid-phase microextraction followed by gas chromatography-mass spectrometry for rapid analysis of volatile organic chemicals in mainstream cigarette smoke

In this work, a novel, simple and efficient method based on solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) was developed to the analysis of volatile organic chemicals (VOCs) in mainstream cigarette smoke (MCS). Using a simple home-made smoking machine device, extraction and concentration of VOCs in MCS were performed by SPME fiber, and the VOCs adsorbed on fiber were desorbed, and analyzed by GC-MS. The extraction fiber types and the desorption conditions were studied, and the method precision was also investigated. After the investigation, the optimal fiber was divinylbenzene/carboxen/polydemethylsiloxane (DVB/CAR/PDMS), and the optimal desorption condition was 250 degrees C for 3 min. The method precision was from 2% to 11%. Finally, the proposed method was tested by its application of the analysis of VOCs in MCS from 10 brands of cigarettes and one reference cigarette. A total of 70 volatile compounds were identified by the proposed method. The experimental results showed that the proposed method was a simple, rapid, reliable, and solvent-free technique for the determination of VOCs in MCS.     

Gas chromatography-mass spectrometry with solid-phase microextraction method for determination of methyl salicylate and other volatile compounds in leaves of<Emphasis Type="Italic"> Lycopersicon esculentum</Emphasis>

Methyl salicylate (MeSA) in many plants is a important signaling compound, which plays an important role in a pathogen-induced defense response. In this paper, gas chromatography-mass spectrometry (GC-MS) with headspace solid-phase microextraction (HS-SPME) was developed for determination of MeSA and other volatile compounds in leaves of a tomato plant (Lycopersicon esculentum). Tomato leaves were ground under liquid nitrogen and sampled by HS-SPME, with a 100 m polydimethylsiloxane fiber, and finally analyzed by GC-MS. Eighteen compounds in the leaves of tomato plant infested by tobacco mosaic virus (TMV) were separated and identified, among them MeSA, which was quantitatively analyzed by the standard addition method. MeSA concentrations higher than 2.0 g g^–1 fresh weight accumulated in leaves of TMV-infested tomato plant as the defense response to TMV. A similar concentration of MeSA in the leaves of MeSA-treated tomato plant was also found. No MeSA in leaves of control tomato plant was detected. These findings suggest that MeSA might be a signaling compound in the tomato plant response to TMV. The present method for determination of MeSA required only simple sample preparation and no organic solvent, and provided an excellent relative standard deviation of less than 5.0% and a low detection limit of 10 ng g^–1 fresh weight for MeSA. These results show that GC-MS-HS-SPME is a simple, rapid and sensitive method for determination of MeSA and other plant-signaling compounds in plant tissues.