Round-robin evaluation of a solid-phase microextraction-gas chromatographic method for reliable determination of trace level ethylene oxide in sterilized medical devices

Medical devices that are sterilized with ethylene oxide (EtO) retain small quantities of EtO residuals, which may cause negative systemic and local irritating effects, and must be accurately quantified to ensure non-toxicity. The goal of this round-robin study is to investigate the capability of a novel solid-phase microextraction-gas chromatographic (SPME-GC) method for trace-level EtO residuals analysis: three independent laboratories conducted a guided experiment using this SPME-GC method, in assessing method performance, ruggedness and the feasibility of SPME fibers. These were satisfactory across the independent laboratories, at the 0.05-5.00 ppm EtO range. This method was then successfully applied to analyze EtO residuals in several sterilized/aerated medical devices of various polymeric composition, reliably detecting and quantifying the trace levels of EtO residuals present ( approximately 0.05 ppm EtO). SPME is a feasible alternative for quantifying trace-level EtO residuals in sterilized medical devices, thereby lowering the limit of quantification (LOQ) by as much as two to three orders of magnitude over the current GC methodology of direct liquid injection.     

碳纳米管顶空固相微萃取测定水中的多溴联苯醚

建立了顶空固相微萃取联结气相色谱-电子捕获检测器（HS-SPME-GC-ECD）测定水中多溴联苯醚的方法。制作了多壁碳纳米管涂层固相微萃取探头。优化了萃取时间,萃取温度,搅拌速度,顶空体积,溶液的pH,离子强度及有机溶剂等影响萃取效率的各种因素。比较了室温和100 ℃顶空萃取和直接萃取的效率。结果表明,室温下直接萃取比顶空萃取的效率高2-4倍,而在100 ℃时顶空萃取比直接萃取的效率高1-8倍。除BDE-154外,无论直接萃取还是顶空萃取,100 ℃时的萃取效率均高于室温。方法的线性范围50-1600 ng/L,相关系数为0.995-0.998,5种多溴联苯醚的最低检出限（S/N=3）为1.14-16.25 ng/L,相对标准偏差（RSD%,n=5）小于10%。本方法用于真实水样的测定,回收率为74.2%-98.7%。     

Time‐of‐flight secondary ion mass spectrometry and gas chromatography–mass spectrometry studies of alkanethiol self‐assembled monolayers on nanoporous gold surfaces

The dimerization of alkanethiol mixtures (hexanethiol, octanethiol, and dodecanethiol) to form self‐assembled monolayers (SAMs) from headspace on nanoporous gold surfaces was studied for the first time using gas chromatography (GC/MS) and time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS). The nanoporous gold surfaces were obtained by an acidic etching of a 585‐gold alloy. Field emission scanning electron microscopy (FE‐SEM) was utilized to study the change of the surface geometry and porosity of the gold surfaces before and after etching. Alkanethiols were deposited from the vapor phase above the thiol solutions (headspace) on nanoporous gold plates and nanoporous gold solid‐phase vmicroextraction (SPME) fibers. The nanoporous gold substrates were analyzed by TOF‐SIMS and GC/MS, respectively. The TOF‐SIMS spectra exhibited various gold–sulfur ion clusters and specific peaks related to the adsorption of thiols such as deprotonated monomers, thiolate–Au, dimers (e.g., dialkyl sulfides–Au and dialkyl disulfides–Au). The GC/MS analysis of headspace extractions of alkanethiol mixtures by nanoporous gold SPME fibers showed a high extraction efficiency of alkanethiol, dialkyl sulfide, and dialkyl disulfide when compared with the commercial SPME fibers (DVB‐CAR‐PDMS and CAR‐PDMS). Different GC/MS optimization factors were studied including the extraction time and desorption temperature.     

Development of a solid‐phase microextraction fiber coated with poly(methacrylic acid‐ethylene glycol dimethacrylate) and its application for the determination of chlorophenols in water coupled with GC

A solid‐phase microextraction (SPME) fiber coated with poly(methacrylic acid‐ethylene glycol dimethacrylate) coupled to GC with a micro electron‐capture detector was developed for the determination of four chlorphenols in water samples for the first time. A novel and simple method for the preparation of this novel SPME fiber was proposed by copolymerization of methacrylic acid and ethylene glycol dimethacrylate in an appropriate solvent using a glass capillary as a “mold”. The factors affecting the polymerization were optimized in detail. Furthermore, the extraction performance of the poly(methacrylic acid‐ethylene glycol dimethacrylate) fiber was evaluated. Moreover, experimental headspace‐SPME parameters, such as extraction temperature, extraction time, salt concentration, stirring speed, and pH, were optimized by orthogonal array experimental designs. Under the optimized conditions, the target analytes were linear in the range of 0.2–50 ng/mL, and the correlation coefficients were all greater than 0.99. RSD was less than 8.9%, and the detection limits were in the range of 0.1–10 ng/L. Four cholorphenols were detected from tap and lake water samples using the proposed method, with the recoveries of spiked natural water samples were ranged from 91.8 to 110.8, and 90.6 to 111.4% for tap and lake water samples, respectively.     

Optimization of headspace sampling using solid‐phase microextraction for chloroanisoles in cork stoppers and gas chromatography–ion‐trap tandem mass spectrometric analysis

In a study aiming to characterize cork off‐flavour for quality control purposes, chloroanisoles were extracted and identified from cork stoppers by means of solid‐phase microextraction (SPME)–gas chromatography–ion‐trap mass spectrometry (GC–ITMS). An experimental design procedure was used to investigate the effects of some experimental parameters on the SPME of 2,4‐dichloroanisole, 2,6‐dichloroanisole, and 2,4,6‐trichloroanisole from cork stoppers by using a Carboxen‐PDMS 75 μm fibre. Variables such as extraction temperature, extraction time, and percentage of ethanol added to the matrix were optimized to improve extraction efficiency of chloroanisoles onto SPME fibre. Instrumental analysis was performed by GC–ITMS in the MS/MS mode. Preliminary analyses on standard solutions allowed selection of the appropriate ionization mode (i. e. electron impact or chemical ionization), providing for each analyte the highest instrumental response. In order to find polynomial functions describing the relationships between variables and responses, the analytical responses, i.e. the chromatographic peak areas, were processed by using the backward multiple regression analysis. For all the analytes the operating conditions providing the highest extraction yield inside the experimental domain considered were found.     

Speciation of inorganic and tetramethyltin by headspace solid‐phase microextraction and gas chromatography–mass spectrometry

A headspace solid‐phase microextraction (HS‐SPME) method coupled to GC‐MS was developed in order to determine trace levels of tetramethyltin (TeMT) and inorganic tin (iSn) after ethylation to tetraethyltin (TeET) in various matrices. The derivatization of iSn and the extraction of both TeMT and iSn as TeET were performed in one step. Sodium tetraethylborate (NaBEt₄) was used as derivatization agent and the volatile derivatives were absorbed on a PDMS‐coated fused silica fiber. The conditions for the HS‐SPME procedure were optimized in order to gain in repeatability and sensitivity. Several critical parameters of GC‐MS were also studied. The detection of TeMT and iSn as TeET peaks was performed by the SIM mode. The precision of the proposed method is satisfactory providing RSD values below 10% for both tin species and good linearity up to 10 μg/L. The developed method was successfully applied to the determination of tin species in several samples like canned fish, fish tissues, aquatic plants, canned mineral water and sea water. The proposed HS‐SPME‐GC‐MS method was proved suitable to monitor the concentration levels of toxic tin compounds in environmental and biological samples.     

Use of two different coating temperatures for a cold fiber headspace solid‐phase microextraction system to determine the volatile profile of Brazilian medicinal herbs

In this study, the experimental extraction conditions on applying headspace solid‐phase microextraction and cold fiber headspace solid‐phase microextraction (CF‐HS‐SPME) procedures to samples of six medicinal herbs commonly found in southern Brazil were optimized. The optimized conditions for headspace solid‐phase microextraction were found to be an extraction temperature of 60°C and extraction time of 40 min. For CF‐HS‐SPME, the corresponding values were 60°C and 15 min. In the case of the coating temperature for the CF‐HS‐SPME system, two approaches were investigated: (i) Temperature of 5°C applied during the whole extraction procedure; and (ii) the use of two fiber temperatures in the same extraction procedure with the aim of extracting the volatile and semivolatile compounds, the ideal condition being 60°C for the first 7.5 min and 5°C for the final 7.5 min. The three extraction procedures were compared. The CF‐HS‐SPME procedure had good performance only for the more volatile compounds whereas the strategy using two coating temperatures in the same procedure showed good performance for all compounds studied. It was also possible to determine the profile for the volatile fraction of each herb studied applying this technique followed by GC‐MS.     

Determination of monocyclic aromatic amines using headspace solid‐phase microextraction based on sol–gel technique prior to GC

In this research, the headspace solid‐phase microextraction (SPME) coupled with GC flame ionization detector was applied for the determination of some monocyclic aromatic amines in real water and urine samples. A sol–gel technique was applied for the preparation of the SPME fibers. Two different sol–gel coatings, (PEG and poly(ethylene glycol) modified with multi‐walled carbon nanotubes [PEG/CNTs]), were prepared and compared. Extraction efficiency of PEG/CNTs was better than PEG fiber in the same conditions. To obtain maximum extraction efficiency, some parameters such as desorption temperature and time, temperature and time of extraction, salt effect, pH, and stirring speed were investigated and optimized for PEG/CNTs fiber. Under optimized conditions, the LODs (S/N = 3) were in the range of 0.5–50 ng/L and limits of quantification (S/N = 10) were between 1 and 500 ng/L. Repeatability (n = 5) was in the range of 3.2–9.1% and reproducibility (n = 3) was obtained from 5.5 to 12.0%. The method was successfully applied to the analysis of real water and urine samples with recoveries from 63.7 to 97.0%.     

QSRR Study of GC Retention Indices of Volatile Compounds Emitted from Mosla chinensis Maxim by Multiple Linear Regression

The volatile compounds emitted from Mosla chinensis Maxim were analyzed by headspace solid‐phase microextraction (HS‐SPME) and headspace liquid‐phase microextraction (HS‐LPME) combined with gas chromatography‐mass spectrometry (GC‐MS). The main volatiles from Mosla chinensis Maxim were studied in this paper. It can be seen that 61 compounds were separated and identified. Forty‐nine volatile compounds were identified by SPME method, mainly including myrcene, α‐terpinene, p‐cymene, (E)‐ocimene, thymol, thymol acetate and (E)‐β‐farnesene. Forty‐five major volatile compounds were identified by LPME method, including α‐thujene, α‐pinene, camphene, butanoic acid, 2‐methylpropyl ester, myrcene, butanoic acid, butyl ester, α‐terpinene, p‐cymene, (E)‐ocimene, butane, 1,1‐dibutoxy‐, thymol, thymol acetate and (E)‐β‐farnesene. After analyzing the volatile compounds, multiple linear regression (MLR) method was used for building the regression model. Then the quantitative structure‐retention relationship (QSRR) model was validated by predictive‐ability test. The prediction results were in good agreement with the experimental values. The results demonstrated that headspace SPME‐GC‐MS and LPME‐GC‐MS are the simple, rapid and easy sample enrichment technique suitable for analysis of volatile compounds. This investigation provided an effective method for predicting the retention indices of new compounds even in the absence of the standard candidates.     

Analysis of anaesthetics and analgesics in human urine by headspace SPME and GC

The determination of widely used anaesthetic and analgesic drugs in biological fluids is of major clinical importance. Typical methods used for sample preparation employ liquid–liquid extraction protocols which are complex, costly, not handy and not amenable to automation. In the present communication, we report the development of a methodology that employs headspace solid‐phase microextraction (HS‐SPME) for the determination of four anaesthetic (lidocaine, midazolam, diazepam and ketamine) and three analgesic drugs (fentanyl, remifentanyl and codeine) in human urine. Important parameters controlling SPME were studied: selection of SPME fibre, type and amount of salt added, preheating and extraction time, extraction temperature, sample volume and desorption time. GC with nitrogen phosphorus detection (GC‐NPD) facilitates sensitive and selective detection of the anaesthetics. The developed method renders an efficient tool for the precise and sensitive determination of the anaesthetics and analgesics in human urine (RSDs ranged from 7.7 to 12.6%, whereas LODs ranged from 0.01 to 1.5 ng/mL). The method was applied to the determination of the anaesthetics and analgesics in human urine from patients that had undergone coronary by‐pass surgery operations. The proposed protocol can function as an attractive alternative for clinical acute intoxications and medico‐legal cases.     

Comparison of membrane assisted solvent extraction,stir bar sorptive extraction,and solid phase microextraction in analysis of tetramine in food

Three environmentally friendly extraction techniques, membrane assisted solvent extraction (MASE), stir bar sorptive extraction (SBSE), and headspace solid phase microextraction (HS‐SPME), were compared for the direct analysis of the highly toxic rodenticide tetramine in food. The optimized MASE method was applied to seven foods fortified with tetramine and compared to previously reported SBSE and HS‐SPME results. Parameters such as the standard addition linearity (MASE (0.964–0.999), SBSE (0.966–0.999), HS‐SPME (0.955–0.999)), recovery (MASE (12–86%), SBSE (36–130%), HS‐SPME (50–200%)), reproducibility (MASE (3.0–30%), SBSE (4.4–9.6%), HS‐SPME (1–12%)), and LOD (MASE (1.6–6.4 ng/g), SBSE (0.2–2.1 ng/g), HS‐SPME (0.9–4.3 ng/g)) were compared.     

Speciation of volatile antimony compounds in culture headspace gases of Cryptococcus humicolus using solid phase microextraction and gas chromatography–mass spectrometry

Direct analysis of the volatile antimony compounds stibine (SbH₃), monomethylantimony, dimethylantimony (Me₂Sb) and trimethylantimony (Me₃Sb) using solid phase microextraction (SPME) with polydimethylsiloxane fibres and gas chromatography–mass spectrometry (GC–MS) is described. The best analyte to background signal ratio was achieved using a 20 min extraction time. Antimony species were separated using a 3% phenylmethylsilicone capillary column operated at a column pressure of 70 kPa, a flow rate of 1.4 ml min^?1 and temperature ramping from 30 to 36 °C at 0.1 °C min^?1. Cryogenic focusing of desorbed species was required to achieve resolution of antimony species. The optimized SPME–GC–MS method was applied to the analysis of headspace gases from cultures of Cryptococcus humicolus incubated with inorganic antimony(III) and (V) substrates. The headspace gases from biphasic (aerobic–anaerobic) biomass‐concentrated culture incubations revealed the presence of SbH₃, Me₂Sb and Me₃Sb. Stibine was the major antimony species detected in cultures amended with inorganic antimony(V). Me₃Sb was the sole volatile antimony species detected when cultures were amended with antimony(III). Copyright © 2002 John Wiley & Sons, Ltd.     

Evaluation of needle trap micro‐extraction and solid‐phase micro‐extraction: Obtaining comprehensive information on volatile emissions from in vitro cultures

Volatile organic compounds (VOCs) emitted from in vitro cultures may reveal information on species and metabolism. Owing to low nmol L⁻¹ concentration ranges, pre‐concentration techniques are required for gas chromatography–mass spectrometry (GC–MS) based analyses. This study was intended to compare the efficiency of established micro‐extraction techniques – solid‐phase micro‐extraction (SPME) and needle‐trap micro‐extraction (NTME) – for the analysis of complex VOC patterns. For SPME, a 75 μm Carboxen®/polydimethylsiloxane fiber was used. The NTME needle was packed with divinylbenzene, Carbopack X and Carboxen 1000. The headspace was sampled bi‐directionally. Seventy‐two VOCs were calibrated by reference standard mixtures in the range of 0.041–62.24 nmol L⁻¹ by means of GC–MS. Both pre‐concentration methods were applied to profile VOCs from cultures of Mycobacterium avium ssp. paratuberculosis. Limits of detection ranged from 0.004 to 3.93 nmol L⁻¹ (median = 0.030 nmol L⁻¹) for NTME and from 0.001 to 5.684 nmol L⁻¹ (median = 0.043 nmol L⁻¹) for SPME. NTME showed advantages in assessing polar compounds such as alcohols. SPME showed advantages in reproducibility but disadvantages in sensitivity for N‐containing compounds. Micro‐extraction techniques such as SPME and NTME are well suited for trace VOC profiling over cultures if the limitations of each technique is taken into account.     

Selective determination of alkylmercury compounds in solid matrices after subcritical water extraction,followed by solid‐phase microextraction and GC–MS

A method for the extraction and determination of methylmercury (MeHg) in solid matrices is presented. Combining the advantages of two extraction techniques—subcritical water extraction (subWE) and solid‐phase microextraction (SPME)—selective separation of MeHg from soils is possible. The procedure is based on extraction with subcritical water without using organic solvents, followed by in situ aqueous‐phase derivatization with sodium tetraethylborate and headspace SPME with a silica fiber coated with poly(dimethylsiloxane). The optimization of the extraction parameters is described. The identification and quantification of the extracted alkylmercury compounds from spiked soil samples is performed by GC–MS after thermal desorption. Copyright © 2000 John Wiley & Sons, Ltd.     

Analysis of volatile oil composition of Citrus aurantium L. by microwave‐assisted extraction coupled to headspace solid‐phase microextraction with nanoporous based fibers

Nanoporous silica was prepared and functionalized with amino propyl‐triethoxysilane to be used as a highly porous fiber‐coating material for solid‐phase microextraction (SPME). The prepared nanomaterials were immobilized onto a stainless steel wire for fabrication of the SPME fiber. The proposed fiber was evaluated for the extraction of volatile component of Citrus aurantium L. leaves. A homemade microwave‐assisted extraction followed by headspace (HS) solid‐phase apparatus was used for the extraction of volatile components. For optimization of factors affecting the extraction efficiency of the volatile compounds, a simplex optimization method was used. The repeatability for one fiber (n = 4), expressed as RSD, was between 3.1 and 8.6% and the reproducibility for five prepared fibers was between 10.1 and 14.9% for the test compounds. Using microwave‐assisted distillation HS‐SPME followed by GC‐MS, 53 compounds were separated and identified in C. aurantium L., which mainly included limonene (62.0%), linalool (7.47%), trans‐β‐Ocimene (3.47%), and caryophyllene (2.05%). In comparison to a hydrodistillation method, the proposed technique could equally monitor almost all the components of the sample, in an easier way, which was rapid and required a much lower amount of sample.     

A novel and rapid extraction protocol for sensitive and accurate determination of prochloraz in orange juice samples: Vortex‐assisted spraying‐based fine droplet formation liquid‐phase microextraction before gas chromatography–mass spectrometry

A novel, ecofriendly, and easy extraction and preconcentration method named as vortex‐assisted spraying‐based fine droplet formation liquid‐phase microextraction was proposed for the determination of prochloraz at trace levels in orange juice samples by gas chromatography–mass spectrometry (GC‐MS). In this novel system, extraction solvent is dispersed by the help of spraying apparatus instead of dispersive solvent. Various parameters of the method were carefully optimized to increase signal‐to‐noise ratio of the analyte. Under the optimum chromatographic and extraction conditions, limit of detection and limit of quantification were calculated as 3.2 and 10.8 μg/kg, respectively. Moreover, enhancement in quantification power for the GC‐MS system was determined as 372 folds based on LOQ comparison. Relative recovery results for orange juice samples were found to be between 95.0–107.7% by utilizing matrix matching calibration. Furthermore, the developed method may be used to efficiently and simply extract other organic compounds for their determinations in several matrices.     

A Novel Hybrid Metal–Organic Framework–Polymeric Monolith for Solid‐Phase Microextraction

This study describes the fabrication of a novel hybrid metal–organic framework– organic polymer (MOF–polymer) for use as a stationary phase in fritless solid‐phase microextraction (SPME) for validating analytical methods. The MOF–polymer was prepared by using ethylene dimethacrylate (EDMA), butyl methacrylate (BMA), and an imidazolium‐based ionic liquid as porogenic solvent followed by microwave‐assisted polymerization with the addition of 25 % MOF. This novel hybrid MOF–polymer was used to extract penicillin (penicillin G, penicillin V, oxacillin, cloxacillin, nafcillin, dicloxacillin) under different conditions. Quantitative analysis of the extracted penicillin samples using the MOF–organic polymer for SPME was conducted by using capillary electrochromatography (CEC) coupled with UV analysis. The penicillin recovery was 63–96.2 % with high reproducibility, sensitivity, and reusability. The extraction time with the proposed fabricated SPME was only 34 min.     

Development of single‐drop microextraction and simultaneous derivatization followed by GC‐MS for the determination of aliphatic amines in tobacco

In this work, for the first time, headspace (HS) single‐drop microextraction and simultaneous derivatization followed by GC‐MS was developed to determine the aliphatic amines in tobacco samples. In the HS extraction procedure, the mixture of derivatization reagent and organic solvent was employed as the extraction solvent for HS single‐drop microextraction and in situ derivatization of aliphatic amine in the samples. Fast extraction and simultaneous derivatization of the analytes were performed in a single step, and the obtained derivatives in the microdrop extraction solvent were analyzed by GC‐MS. The optimized experiment conditions were: sample preparation temperature of 80°C and time of 30 min, HS extraction solvent (the mixture of benzyl alcohol and 2,3,4,5,6‐pentafluorobenzaldehyde) volume of 2.0 μL, extraction time of 90 s. With the optimal conditions, the method validations were also studied. The method has good linearity (R² more than 0.99), accepted precision (RSD less than 13%), good recovery (98–104%) and low limit of detection (0.11–0.97 μg/g). Finally, the proposed technique was successfully applied to the analyses of aliphatic amines in tobacco samples of seven different brands. It was further demonstrated that the proposed method offered a simple, low‐cost and reliable approach to determine aliphatic amines in tobacco samples.     

A platinized stainless steel fiber with in‐situ coated polyaniline/polypyrrole/graphene oxide nanocomposite sorbent for headspace solid‐phase microextraction of aliphatic aldehydes in rice samples

The surface of a stainless steel fiber was made larger, porous and cohesive by platinizing for tight attachment of its coating. Then it was coated by a polyaniline/polypyrrole/graphene oxide (PANI/PP/GO) nanocomposite film using electrochemical polymerization. The prepared PANI/PP/GO fiber was used for headspace solid‐phase microextraction (HS‐SPME) of linear aliphatic aldehydes in rice samples followed by GC‐FID determination. To achieve the highest extraction efficiency, various experimental parameters including extraction time and temperature, matrix modifier and desorption condition were studied. The linear calibration curves were obtained over the range of 0.05–20 μg g⁻¹ (R ² > 0.99) for C₄–C₁₁ aldehydes. The limits of detection were found to be in the range of 0.01–0.04 μg g⁻¹. RSD values were calculated to be <7.4 and 10.7% for intra‐ and inter‐day, respectively. The superiority of the prepared nanocomposite SPME fiber was established by comparison of its results with those obtained by polydimethylsiloxane, carbowax–divinylbenzene, divinylbenzene–carboxen–polydimethylsiloxane and polyacrylate commercial ones. Finally, the nanocomposite fiber was used to extract and determine linear aliphatic aldehydes in 18 rice samples.     

Solid‐phase microextraction of methadone in urine samples by electrochemically co‐deposited sol–gel/Cu nanocomposite fiber

Electrochemically co‐deposited sol–gel/Cu nanocomposites have been introduced as a novel, simple and single‐step technique for preparation of solid‐phase microextraction (SPME) coating to extract methadone (MDN) (a synthetic opioid) in urine samples. The porous surface structure of the sol–gel/Cu nanocomposite coating was revealed by scanning electron microscopy. Direct immersion SPME followed by HPLC‐UV determination was employed. The factors influencing the SPME procedure, such as the salt content, desorption solvent type, pH and equilibration time, were optimized. The best conditions were obtained with no salt content, acetonitrile as desorption solvent type, pH 9 and 10 min equilibration time. The calibration graphs for urine samples showed good linearity. The detection limit was about 0.2 ng mL⁻¹. Also, the novel method for preparation of nanocomposite fiber was compared with previously reported techniques for MDN determination. The results show that the novel nanocomposite fiber has relatively high extraction efficiency.