A Review of Stir Bar Sorptive Extraction

Stir bar sorptive extraction (SBSE) is an extraction technique for enrichment of volatile and semi-volatile organic compounds from aqueous and gaseous media. After exposure to a sample, the stir bar, which is covered in a layer of a polysiloxane is subsequently removed and the sorbed compounds are then either thermally desorbed, and analysed by GC-MS or desorbed by means of a liquid, for improved selectivity or for interfacing to an LC system.The technique has been applied successfully to trace analysis in environmental, biomedical and food applications. Applications of SBSE to environmental, foodstuffs and pharmaceutical and biomedical samples are given.

     

Stir bar sorptive extraction for trace analysis

Stir bar sorptive extraction (SBSE) was introduced in 1999 as a solventless sample preparation method for the extraction and enrichment of organic compounds from aqueous matrices. The method is based on sorptive extraction, whereby the solutes are extracted into a polymer coating on a magnetic stirring rod. The extraction is controlled by the partitioning coefficient of the solutes between the polymer coating and the sample matrix and by the phase ratio between the polymer coating and the sample volume. For a polydimethylsiloxane coating and aqueous samples, this partitioning coefficient resembles the octanol-water partitioning coefficient. In comparison to solid phase micro-extraction, a larger amount of sorptive extraction phase is used and consequently extremely high sensitivities can be obtained as illustrated by several successful applications in trace analysis in environmental, food and biomedical fields. Initially SBSE was mostly used for the extraction of compounds from aqueous matrices. The technique has also been applied in headspace mode for liquid and solid samples and in passive air sampling mode. In this review article, the principles of stir bar sorptive extraction are described and an overview of SBSE applications is given.     

Sequential stir bar sorptive extraction for uniform enrichment of trace amounts of organic pollutants in water samples

A novel extraction procedure for stir bar sorptive extraction (SBSE) termed sequential SBSE was developed. Compared to conventional SBSE, sequential SBSE provides more uniform enrichment over the entire polarity/volatility range for organic pollutants at ultra-trace levels in water. Sequential SBSE consists of a SBSE performed sequentially on a 5-mL sample first without modifier using one stir bar, then on the same sample after addition of 30% NaCl using a second stir bar. The first extraction with unmodified sample is mainly targeting solutes with high Kow (logKow>4.0), the second extraction with modified sample solution (containing 30% NaCl) is targeting solutes with low and medium Kow (logKow<4.0). After extraction the two stir bars are placed in a single glass desorption liner and are simultaneously desorbed. The desorbed compounds were analyzed by thermal desorption and gas chromatography-mass spectrometry (TD-GC-MS). Recovery of model compounds consisting of 80 pesticides (organochlorine, carbamate, organophosphorus, pyrethroid, and others) for sequential SBSE was evaluated as a function of logKow (1.70-8.35). The recovery using sequential SBSE was compared with those of conventional SBSE with or without salt addition (30% NaCl). The sequential approach provided very good recovery in the range of 82-113% for most of the solutes, and recovery less than 80% for only five solutes with low Kow (logKow<2.5), while conventional approaches (with or without salt addition) showed less than 80% recovery for 23 and 41 solutes, respectively. The method showed good linearity (r2>0.9900) and high sensitivity (limit of detection: <10ngL(-1)) for most of the model compounds even with the scan mode in the MS. The method was successfully applied to screening of pesticides at ngL(-1) level in river water samples.     

Stir-bar sorptive extraction: A view on method optimisation,novel applications,limitations and potential solutions

Introduced in 1999 as a novel solventless sample preparation method, stir-bar sorptive extraction (SBSE) has become a popular analytical technique for the pre-concentration of organic compounds into a polydimethylsiloxane (PDMS)-coated stir-bar. In the last 10 years, hundreds of applications in the environmental, food and biomedical fields can be found in the literature. However, only PDMS-coated stir-bars are commercially available, which reduces the applicability of SBSE to the extraction of the non-polar compounds due to the poor extractability of more polar analytes. In this review, a view on method optimisation, limitations, potential solutions such as in-house coatings and derivatisation and novel applications in multi-residue analysis and passive sampling are revised.     

Optimisation of stir bar sorptive extraction for the analysis of volatile phenols in wines

An easy, fast and reliable analytical method is proposed for the determination of the concentration of volatile phenols (ethyl- and vinylphenols) in wines. The novel stir bar sorptive extraction (SBSE) technique is employed, following a simple and fast procedure that allows 15 samples to be extracted simultaneously using very small sample volume. Extracts are desorbed in a thermodesorption system (TDS) coupled on-line to a gas chromatograph-mass spectrometry system. The SBSE offers better recovery and linear regression coefficient (r2) for the four volatile phenols than solid-phase extraction (SPE). The mass spectrometric detection in selected ion monitoring mode contributes to the lower detection limit and good sensibility obtained with this method.     

ICE Concentration Linked with Extractive Stirrer (ICECLES)

Trace and ultra-trace analysis can be difficult to achieve, especially for polar, more volatile, and/or thermally unstable analytes. A novel technique, coined ICE Concentration Linked with Extractive Stirrer (ICECLES), may help address this problem. The implementation of ICECLES described here combines stir bar sorptive extraction (SBSE) with freeze concentration (FC), where an aqueous solution is frozen during SBSE in order to concentrate analytes into a polydimethylsiloxane (PDMS) coated stir bar. Five test probe molecules with a range of log K_ows (2-butanol, benzyl alcohol, benzaldehyde, dimethyl trisulfide and bromobenzene) were prepared from aqueous solutions using ICECLES. Thermal desorption gas–chromatography mass–spectrometry was then used to quantify these analytes. Parameters affecting the performance of ICECLES (e.g., freeze rate) were evaluated, with extraction at lower speeds resulting in higher extraction efficiencies, whereas the freeze rate and initial analyte concentration only had a minor effect. ICECLES produced much higher extraction efficiencies than SBSE alone, with signal enhancements of up to 474× SBSE. ICECLES also provided excellent reproducibility and lower LODs than SBSE for all compounds tested. ICECLES performed well when used to analyze multiple triazine pesticides and breakdown products in environmental surface waters. Overall, the ICECLES technique was excellent at preparing aqueous samples for trace analysis and shows promise as a novel analytical sample preparation technology.     

Recent developments in stir bar sorptive extraction

As a crucial step in qualitative and quantitative analysis, sample pretreatment is commonly used to isolate the target analytes, concentrate them, or convert them into the forms tailored to the instrumental analysis. In recent years, there has been a trend for sample pretreatment techniques to become more miniaturized and more environmentally friendly. Stir bar sorptive extraction (SBSE), which was developed in 1999, is such an environmentally friendly microextraction technique. Compared with other microextraction techniques, including solid phase microextraction and liquid phase microextraction, SBSE provides a higher extraction efficiency and better reproducibility owing to the much greater amount of the extraction phase, and no special skills are required. However, there are some problems associated with SBSE, such as the limited applicable coatings, coating abrasion of the laboratory-made stir bar, and the difficulty in automation, which restrict the further improvement and application of SBSE. This review focuses on the development of SBSE in the past decade, in terms of coating preparation, automated systems, novel extraction modes, its use with various instruments, and applications in food, environmental, and biological samples.

搅拌棒吸附萃取结合气相色谱/质谱/质谱法同时测定饮料和果酱中的7种防腐剂

建立了搅拌棒吸附萃取进行前处理,气相色谱-质谱/质谱法测定饮料和果酱中7种食品防腐剂的方法.饮料和果酱样品用pH=3的30% NaCl溶液稀释,使用搅拌棒进行吸附萃取,吸附在搅拌棒上的防腐剂在热解析单元进行热解析,在冷进样口进行捕集后通过程序升温进入气相色谱,使用串联质谱的多反应监测(MRM)同时检测饮料和果酱中的7种防腐剂(苯甲酸、山梨酸以及对羟基苯甲酸甲酯、对羟基苯甲酸丙酯、对羟基苯甲酸异丙酯、对羟基苯甲酸异丁酯和对羟基苯甲酸庚酯).苯甲酸、山梨酸在40～400 mg/L浓度范围内,对羟基苯甲酸甲酯、对羟基苯甲酸丙酯、对羟基苯甲酸异丙酯和对羟基苯甲酸异丁酯在4～40 mg/L浓度范围内,对羟基苯甲酸正庚酯在0.4～4 mg/L浓度范围内,各组分响应峰面积与其相应浓度呈良好相关性,r>0.99.苯甲酸和山梨酸的检出限分别为37和47 mg/L,对羟基苯甲酸酯类为0.62～6.67 mg/L.方法的回收率为84.0%～125.0%;精确度为3.0%～18.1%.本方法灵敏度高,能够同时快速检测饮料和果酱中7种防腐剂.     

Optimisation of stir bar sorptive extraction applied to the determination of volatile compounds in vinegars

Stir bar sorptive extraction (SBSE) was evaluated for analysing volatile compounds in vinegar. The extraction and desorption analytical conditions have been optimised using a two-level factorial design expanded further to a central composite design. This chemometric tool is very appropriate in screening experiments where the aim is to investigate several possibly influential and/or interacting factors. For the extraction step, the optimum analytical conditions were: sample volume 25 ml without dilution, sampling time 120 min, NaCl content 5.85 g, and stirring speed 1250 rpm. For the desorption step, the optimised analytical conditions were: desorption temperature 300 degrees C, cryofocusing temperature -140 degrees C, flow of helium 75 ml min(-1), and desorption time 10 min. The SBSE procedure developed shows detection limits, and linear ranges adequate for analysing this type of compounds. The repeatability values obtained were lower than 10%. SBSE is a very simple, solvent-free, fast technique with better sensitivities, in general, than SPME. However, a disadvantage of this technique is that, up to now, the stir bar offers a limited enrichment capability for polar compounds because is only available with PDMS coating.     

搅拌棒吸附萃取涂层研制进展

搅拌棒吸附萃取(SBSE)是20世纪90年代末发展起来的一种新型无溶剂样品前处理技术,具有固定相体积大、萃取容量高、无需外加搅拌子、可避免竞争性吸附、能在自身搅拌的同时实现萃取富集等优点,已广泛应用于环境、食品和生物等复杂样品中目标物质的痕量分析。涂层是SBSE技术的核心,决定了萃取选择性和容量。本文简要介绍了SBSE涂层的萃取原理、萃取解吸模式及其影响因素,重点阐述了近年SBSE涂层制备技术与方法,探讨了SBSE涂层发展中的不足,并展望了其发展趋势。     

Stir bar sorptive extraction for central nervous system drugs from biological fluids

A review with 75 references is presented that deals with the reported methods for analysis of some important central nervous system (CNS) drugs in biological fluids utilizing stir bar sorptive extraction (SBSE) technique covering the years from 2000 to 2008. The theoretical aspects of SBSE, as well as an significant number of applications have been published, showing the advantages of this technique over the classical extraction techniques (liquid–liquid extraction (LLE) and solid-phase extraction (SFE). In this review, recent SBSE developments and a focus on the development of new instrumental approaches and sorbent phases are presented.     

搅拌棒固相萃取的研究进展

作为一种新型的环境友好型样品前处理技术,搅拌棒固相萃取(SBSE)集萃取、净化和富集为一体,已经在环境监测、食品安全和生物分析等领域进行了广泛应用。本文结合作者所在研究小组的研究工作,对近几年来SBSE技术的发展进行综述,重点阐述了各种新涂层的研究和应用,同时就SBSE发展方向提出了展望。     

Comparison of stir bar sorptive extraction and solid-phase microextraction to determine halophenols and haloanisoles by gas chromatography-ion trap tandem mass spectrometry

Solid-phase microextraction by immersion (IS-SPME) and headspace mode (HS-SPME), together with stir bar sorptive extraction (SBSE), have been assayed in combination with gas chromatography-ion trap tandem mass spectrometry (MS/MS) for analysing 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, 2,4,6-tribromophenol, 2,4,6-trichloroanisole, 2,3,4,6-tetrachloroanisole and 2,4,6-tribromoanisole in different liquid matrices. Once, the optimization of MS/MS fragmentation analysis was carried out, sample enrichment was performed using the three mentioned extraction methods, and comparison through the determination of linearity, and LOD and LOQs were carried out. SBSE and IS-SPME methods described enabled us to determine the target compounds at ng/l levels, concentrations lower than their olfactory threshold, which is not the case of HS-SPME. SBSE showed a higher concentration capability than both SPME techniques, especially when compared to the HS-SPME mode. Thus, SBSE should be the definitive technique to analyse halophenols and haloanisoles in aqueous matrices. SBSE has been also applied to nine aqueous matrices as different as tap water, wines or commercial lemon juice extract.     

Coupling stir bar sorptive extraction‐dispersive liquid–liquid microextraction for preconcentration of triazole pesticides from aqueous samples followed by GC‐FID and GC‐MS determinations

Stir bar sorptive extraction (SBSE) combined with dispersive liquid–liquid microextraction (DLLME) has been developed as a new approach for the extraction of six triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole, triticonazole and difenconazole) in aqueous samples prior to GC‐flame ionization detection (GC‐FID). A series of parameters that affect the performance of both steps were thoroughly investigated. Under optimized conditions, aqueous sample was stirred using a stir bar coated with octadecylsilane (ODS) and then target compounds on the sorbent (stir bar) were desorbed with methanol. The extract was mixed with 25 μL of 1,1,2,2‐tetrachloroethane and the mixture was rapidly injected into sodium chloride solution 30% w/v. After centrifugation, an aliquot of the settled organic phase was analyzed by GC‐FID. The methodology showed broad linear ranges for the six triazole pesticides studied, with correlation coefficients higher than 0.993, lower LODs and LOQs between 0.53–24.0 and 1.08–80.0 ng/mL, respectively, and suitable precision (RSD < 5.2%). Moreover, the developed methodology was applied for the determination of target analytes in several samples, including tap, river and well waters, wastewater (before and after purification), and grape and apple juices. Also, the presented SBSE‐DLLME procedure followed by GC‐MS determination was performed on purified wastewater. Penconazole, hexaconazole and diniconazole were detected in the purified wastewater that confirmed the obtained results by GC‐FID determination. In short, by coupling SBSE with DLLME, advantages of two methods are combined to enhance the selectivity and sensitivity of the method. This method showed higher enrichment factors (282–1792) when compared with conventional methods of sample preparation to screen pesticides in aqueous samples.     

Comparison of micro-scale simultaneous distillation-extraction and stir bar sorptive extraction for the determination of volatile organic constituents of grape juice

Traditional micro-scale simultaneous distillation-extraction (SDE) and stir bar sorptive extraction (SBSE) were compared for their effectiveness in the extraction of volatile organic compounds in a synthetic grape juice and a real grape juice (Huxelrebe, a variety of half Muscat ancestry) from an English vineyard. The novel immersion-mode SBSE method, using stir bars with PDMS sorbent, was optimised using the synthetic grape juice. Although mean percent relative recoveries and reproducibilities (%CV) of the SBSE method were inferior to SDE (28.4 and 8.5%, respectively, against 86.9 and 6.3%), the former method proved to be significantly more sensitive: 126 aroma compounds in Huxelrebe grape juice were identified using SBSE, against 98 using SDE. This allowed the identification of a number of volatile components that have not been reported previously in the juice or wine from the grapes of Muscat varieties.     

Optimization of a multi-residue screening method for the determination of 85 pesticides in selected food matrices by stir bar sorptive extraction and thermal desorption GC-MS

A multi-residue method to determine 85 pesticides, including organochlorine pesticides, carbamates, organophosphorus pesticides, and pyrethroids, in vegetables, fruit, and green tea, has been developed. The method is based on stir bar sorptive extraction (SBSE) coupled to thermal desorption (TD) and retention time locked (RTL) GC-MS operating in the scan mode. Samples are extracted with methanol and diluted with water prior to SBSE. Dilution of the methanol extract before SBSE was optimized to obtain high sensitivity and to minimize adsorption onto the glass wall of the extraction vessel as well as to minimize sample matrix effects (particularly for the pesticides with high log K(o,w) values). The optimized method consists of a dual SBSE extraction performed simultaneously on respectively a twofold and a fivefold diluted methanol extract. After extraction, the two stir bars are placed in a single glass thermal desorption liner and are simultaneously desorbed. The method showed good linearity (r2 > 0.9900) and high sensitivity (limit of detection: < 5 microg kg(-1)) for most of the target pesticides. The method was applied to the determination of pesticides at low microg kg(-1) in tomato, cucumber, green soybeans, spinach, grapes, and green tea.     

An alternative method for analysis of food taints using stir bar sorptive extraction

The determination of taints in food products currently can involve the use of several sample extraction techniques, including direct headspace (DHS), steam distillation extraction (SDE) and more recently solid phase microextraction (SPME). Each of these techniques has disadvantages, such as the use of large volumes of solvents (SDE), or limitations in sensitivity (DHS), or have only been applied to date for determination of individual or specific groups of tainting compounds (SPME). The use of stir bar sorptive extraction (SBSE) has been evaluated as a quantitative screening method for unknown tainting compounds in foods. A range of commonly investigated problem compounds, with a range of physical and chemical properties, were examined. The method was optimised to give the best response for the majority of compounds and the performance was evaluated by examining the accuracy, precision, linearity, limits of detection and quantitation and uncertainties for each analyte.For most compounds SBSE gave the lowest limits of detection compared to steam distillation extraction or direct headspace analysis and in general was better than these established techniques. However, for methyl methacrylate and hexanal no response was observed following stir bar extraction under the optimised conditions.The assays were carried out using a single quadrupole GC-MS in scan mode. A comparison of acquisition modes and instrumentation was performed using standards to illustrate the increase in sensitivity possible using more targeted ion monitoring or a more sensitive high resolution mass spectrometer. This comparison illustrated the usefulness of this approach as an alternative to specialised glassware or expensive instrumentation. SBSE in particular offers a ‘greener’ extraction method by a large reduction in the use of organic solvents and also minimises the potential for contamination from external laboratory sources, which is of particular concern for taint analysis.     

整体式吸附萃取搅拌棒在检测环境水样中镉离子含量方面的应用

通过逐步聚合反应制备了一种新型整体式吸附萃取搅拌棒,将其应用于环境水中镉离子的吸附萃取.考察了介质酸度、搅拌速率、吸咐时间、解吸溶剂和时间等实验条件对吸附量的影响.控制溶液pH为6.0,搅拌棒转速为300 r/min,吸附30 min,5% HNO3作为解吸液解吸10 min,采用等离子体原子发射光谱仪对Cd离子进行检...     

聚酰亚胺固相萃取搅拌棒的制备及其在环境水中酚类的分析应用

利用相转换法制备了聚酰亚胺吸附萃取搅拌棒,用5种有机酚作为评价标样,并与现有商品化吸附萃取搅拌棒进行比较。优化了萃取搅拌速度、溶液离子强度、萃取温度、萃取时间以及热解析温度和时间。在最佳实验条件下,100 mL 样品,30% NaCl,在25℃下,经活化5 min 后的聚酰亚胺吸附搅拌棒萃取30 min (800 r/ min),然后300℃热解析4 min,使目标物脱附,再进行色谱分析。目标物在大于两个数量级浓度范围内具有良好的线性(R≥0.9995),定量限(LOQ,S/ N=10)为0.028~0.123μg/ L,重复性为1.6%~9.7%。将SBSE 与气相色谱-质谱联用,对海水、自来水和污水中的酚类进行定性与定量分析,结果表明,聚酰亚胺吸附萃取搅拌棒具有良好的选择性,最高热解析温度350℃,在分析水中痕量极性化合物领域具有广阔应用前景。     

Review of SBSE Technique for the Analysis of Pesticide Residues in Fruits and Vegetables

Stir bar sorptive extraction (SBSE) is a microextraction technique, introduced to overcome the problem of limited extraction capacity and fragile fiber coatings inherent in the solid phase microextraction technique. The major limitations of the SBSE technique are that only polydimethylsiloxane has been commercially available, this reduces its use to non-polar analytes, and its tedious reconstitution step which can lead to loss of analytes and introduction of impurities. The current trend has been aimed at the use of other materials, some of which are commercially available, such as restricted access materials, carbon adsorbents, molecularly imprinted polymers, ionic liquids, microporous monoliths, sol–gel prepared coatings and dual phase material. This has greatly helped in widening the applications of SBSE for pesticide analysis in fruits and vegetables and other matrices. The introduction of a thermal desorption unit which eliminates the reconstitution step of the stir bar in organic solvents before instrumental analysis has helped to automate the extraction method online with gas chromatography. This paper reviews the use of SBSE in pesticide residues analysis in fruits and vegetables, with a view on sample preparation steps, method optimization and validation of analytical figures of merit.