Stir Bar Sorptive Extraction Technique Research Articles

Green Analytical Method for Perfluorocarboxylic Acids (PFCAs) in Water of Stir Bar Sorptive Extraction Coupled with Thermal Desorption–Gas Chromatography—Mass Spectroscopy

Perfluoroalkyl carboxylic acids (PFCAs) are a significant group of per- and polyfluoroalkyl substances (PFASs). They are persistent organic chemicals manufactured for their resistance to heat, water, and stains. PFCAs are ubiquitous in the environment, particularly in surface water and wastewater, because they are widely used in everyday consumer products. This contamination poses a risk to drinking water supplies and human health, necessitating sensitive and effective analytical methods. Traditional liquid chromatography–tandem mass spectrometry (LC-MS/MS) is commonly used but involves complex sample handling and high costs. In this study, we developed an enhanced stir bar sorptive extraction (SBSE) method coupled with thermal desorption–gas chromatography–mass spectrometry (TD-GC-MS) for the analysis of PFCAs in water. This method demonstrates linearity, with R2 values from 0.9892 to 0.9988, and low limits of detection (LOD) between 21.17 ng/L and 73.96 ng/L. Recovery rates varied from 47 to 97%, suggesting efficient extraction. Compared to traditional methods, the developed SBSE technique requires only a 1 mL sample volume and minimal amounts of solvents, enhancing eco-friendliness and reducing potential contamination and handling errors. This method also demonstrated good precision and robustness across various water matrices. Overall, the developed method offers a precise, eco-friendly, and reliable approach for analyzing PFCAs in diverse water samples.

Volatile profiles of Murcott and Ponkan mandarins obtained by stir bar sorptive extraction technique and their contributions to the fruit aroma.

Citrus species have undergone immense diversification ever since their ancestral origin. Ponkan and Murcott are two mandarin varieties widely consumed in Brazil and their aroma producing active compounds have not yet been extensively investigated. The present study analyzed the volatile constituents of the Ponkan and Murcott varieties employing the stir bar sorptive extraction (SBSE) technique and gas chromatography-mass spectrometry (GC-MS) analysis for the first time. Extraction was performed using the two phases of Twister bar, polydimethyl siloxane (PDMS), and ethylene glycol (EG) silicone in immersion and headspace modes. Among the detected 62 compounds comprising alcohols, aldehydes, esters, terpenes, and others identified, 55 and 37 compounds in the Ponkan and Murcott variety were determined, respectively, from both immersion and headspace modes using the two phases of Twister bar. From the odor active values, the Ponkan was characterized with the domination of compounds such as hexanal, decanal, nonanal, (E)-2-hexanal, ethyl hexanoate, d-limonene, linalool, and geraniol. Similarly, the Murcott variety was characterized with predominant compounds, namely, nonanal, octanal, hexanal, (E)-2-hexanal, ethyl hexanoate, d-limonene, and linalool. The profile of volatile compounds was found to be unique in both the varieties studied, and SBSE technique with GC-MS analysis favored the characterization of their respective profile due to the high amount of phase in the Twister bars, when compared to similar techniques, like solid phase microextraction. The PDMS Twister bar showed better capacity of adsorption of volatile compounds, since it is a relatively low-polarity polymer, which discriminates less analytes with different structures and polarities sampled from complex matrices, such as fruits juice.

“The Gems of Water”: a co-created scientist-citizen approach for water quality monitoring

To better understand local water quality pollution by organic contaminants and how it affects communities around the world, “The Gems of Water” project aims to build a co-creative global scientist-citizen approach, actively engaging citizens and connecting them to scientists and to advanced water monitoring tools. The project applies the Stir Bar Sorptive Extraction technique with an advanced wide-screening method, used to assess the occurrence of agrochemicals, industrial compounds and pharmaceuticals in surface and groundwaters. In collaboration between Coral Conservation and the Joint Research Centre (JRC) of the European Commission, a study was conducted to identify contamination patterns which could be affecting the coral reef by investigating water quality in local rivers in the south Caribbean region of Costa Rica, an area characterized by agricultural activities linked to bananas production. Coral Conservation is a youth-led non-governmental organization focused on activities for the conservation and protection of the coral reef. Sampling locations for the study were jointly determined with members of the Coral Conservation group and included 13 sampling points from 3 different rivers and 2 wells. The pilot study allowed evaluation of the workflow for scientist-citizen collection of water quality data, whereby participants from the local community conduct sampling and extraction activities, while the wide-screening analysis of about 230 contaminants is performed at the JRC Water Laboratory. Considering the lessons learned through the Costa Rican pilot case, in this paper we discuss the elements required for successful scientist-citizen projects. Challenges are described and outlooks provided to improve citizens’ engagement projects and others participatory water quality monitoring activities. “The Gems of Water” project contributes to data collection of rarely monitored compounds in rural and remote areas through a scientist-citizen approach, addressing knowledge gaps on water quality and building bridges between science and society. The outlook is for such an innovative approach to support bottom-up management actions which can lead to alternative solutions in water quality management.

Optimization of stir bar sorptive extraction (SBSE) and multi-stir bar sorptive extraction (mSBSE) to improve must volatile compounds extraction

The aromatic compounds present in grapes are found in very low concentrations, since, for their determination, a previous step of selective extraction is necessary. In this work we optimize and compare, for the first time, the techniques of extraction by stir bar sorption (SBSE) and multi-stir bar sportive extraction (mSBSE), with the aim of analyzing the must volatile composition. For this purpose, two randomized factorial designs were carried out in which the following factors and levels were combined and optimized: for SBSE, extraction mode (headspace (HS), direct immersion (DI), and both at the same time), extraction speed (500/1000 rpm), extraction time (1/3/6 h), extraction temperature (20/40/60 °C) and NaCl addition (with and without NaCl, and sequential); and for mSBSE: extraction speed (500/1000 rpm), extraction time (1/3/6 h), extraction temperature (20/40/60 °C), and NaCl addition (with and without). The results showed that SBSE technique provided a higher extraction of volatile compounds than mSBSE. After performing principal component analysis (PCA) and analysis of variance (ANOVA) multifactorial, it was concluded that the best conditions for SBSE were: HS, 500 rpm, 6 h, 60 °C and adding NaCl (sequential); and for mSBSE were: 500 rpm, 6 h, 60 °C and without NaCl.

Determination of volatile compounds during deterioration of African opaque beer using a stir bar sorptive extraction technique and gas chromatography-high resolution mass spectrometry

Opaque beer traditional to African communities undergoes quick deterioration and is consumed within 7 days of its production. The current study has utilized a stir bar sorptive extraction technique followed by GC-HRT determination to trace variations of 84 volatile compounds in four opaque beers commonly brewed in South Africa over the 7-day shelf life period. The major fruity esters were observed to increase up to Day 4 and eventually decreasing until Day 7 where their levels were finally lower than Day 1. Aldehydes reduced drastically and were less than 50% on Day 2 and becoming almost undetectable at Day 7. The common beer alcohols (phenylethyl alcohol and 3-methyl-1-butanol) decreased during beer shelf life while phenolics with undesirable medicinal tastes (creosol and p-cresol) increased up to 24-fold by Day 7. This study might open future research perspectives around opaque beer traditional to African rural communities.

Differentiation of volatile aroma components in organically and conventionally produced apples by stir bar sorptive extraction combined with gas chromatography and EI/CI TOF mass spectrometry

SummaryVolatile aroma components and contents of organically and conventionally produced apples of the cultivars Elstar, Jonagold, Jonagored and Braeburn were studied. In three cultivars investigated, the aroma contents of organically produced apples were significantly lower (Elstar 16%, Jonagold 29%, Jonagored 68%). For Braeburn, no statistically significant difference was observed. In particular, the main aroma components were present at much lower concentrations in organically produced apples. In all apple cultivars, these were hexanal, trans‐2‐hexenal, 2‐methylbutylacetate and hexylacetate. twenty‐three aroma components were identified in total, in different relative ratios in the different apple cultivars: saturated esters, saturated and unsaturated aldehydes and alcohols. Some components identified in the conventionally produced cultivars were not present in the organically produced cultivars at all. The aroma components were extracted from juice freshly prepared from the apples by stir bar sorptive extraction (SBSE) technique and characterised by FID gas chromatography and EI/CI TOF mass spectrometry.

Manyetik karıştırma çubuğu ile ekstraksiyon tekniği ile yerüstü sularında sipermetrin analizi

Amaç: Bu çalışmada, Marmara Bölgesi’nde belirlenen noktalardan alınan 11 adet yer üstü suyunu manyetik karıştırma çubuğu ile ekstraksiyon tekniği kullanılarak gaz kromatografisi-üçlü quadrupole kütle spektrometresi cihazı ile sipermetrin analizi amaçlandı.Gereç ve Yöntem: Yerüstü su kalitesi yönetmeliğinde bahsi geçen sipermetrin parametresinin manyetik karıştırma çubuğu ile ekstraksiyon yöntemi kullanılarak analiz edilmesi amaçlandı. Bunun için Marmara Bölgesi’nde daha önceden belirlenen noktalardan numuneler alındı ve manyetik karıştırma çubuğu ile ekstraksiyon yöntemiyle gaz kromatografisi-üçlü quadrupole kütle spektrometresi cihazında analiz gerçekleştirildi.Bulgular: Marmara Bölgesi’nde gerçekleştirilen deneysel çalışmalarda, gaz kromatografisi-üçlü quadrupole kütle spektrometresi manyetik karıştırma çubuğu ile ekstraksiyon yöntemi ile 11 adet numune içerisinden üç adet numunede sipermetrin miktarı tespit edildi. Metot iki farklı kişi tarafından gerçekleştirilen verifikasyon çalışmaları ile doğrulandı. Sonuç: Yapılan çalışmalar sonucu Marmara Bölgesi’nden alınan numunelerde yönetmeliklerde belirlenen seviyelerin altında sipermetrin tespit edilmiştir. Bu sonuç bölgede yaşayan insanlar için olumlu bir gelişmedir. Kocaeli bölgesi genel olarak sanayi ağırlıklı üretim yaptığı için tarımsal faaliyetler ülkemizin diğer bölgelerine göre daha az görülmektedir. Sipermetrin tespit edilmesi veya çok az tespit edilmesinin temel sebebi bu olabilir. Bu ve buna benzer çalışmaların ülkemizin özellikle tarım faaliyeti çok olan yerlerinde yapılması önem teşkil etmektedir. Çünkü ülkemizde tarımda verimliliği artırmak ve zararlı böcek ve haşerelerden kurtulmak için pestisit ürünleri bilinçsiz bir şeklide kullanılmaktadır. Bu konuda çiftçilik ile uğraşan halkımızın uyarılması ve bilinç kazandırılması gerekmektedir. Ayrıca devletin yetkili makamları bu konuda denetimlerini sıklaştırmalı ve bu çerçevede tedbirler almalıdır. Eğer tarımda pestisit kullanımı kontrolsüz bir şekilde devam ederse bu durum uzun vadede halkımızın sağlık problemlerin artmasına ve özellikle kanser oranlarının yükselmesine neden olacaktır.

Fabrication, characterization, and application of zeolitic imidazolate framework-8/acrylate monolithic polymer as a composite phase for stir bar sorptive extraction

Zeolitic imidazolate framework-8/polyacrylate monolithic (ZIF-8/PA) polymers have been prepared and optimized as a multifunctional material and used for application in stir bar sorptive extraction technique. The coating of ZIF-8/PA stir bar was characterized by FT-IR, XRD, and SEM techniques in terms of chemical structure, surface morphology, and composition homogeneity. Also, the extraction performance of prepared stir bars was obtained through the extraction of carvedilol and haloperidol from aqueous solutions. The intra- and inter-batch reproducibilities of stir bar fabrication were obtained 6.6 and 7.0%, respectively and the enrichment factors were in the range of 94–134. The optimum extraction and desorption conditions were achieved at sample pH value of 10, 90 min extraction time, 10 min desorption time, 40 °C desorption temperature and methanol as the desorption solvent for both analytes. At the optimum conditions the linear ranges were 3.8–500 µg L−1 for carvedilol and 10.7–500 µg L−1 for haloperidol with determination coefficients of over than 0.9935. The limits of detection of the method were 1.2 and 3.2 μg L−1 for carvedilol and haloperidol, respectively. The intra- and inter-day accuracies and precisions of the method were monitored at three concentration levels of each analyte. The recoveries were between 83 and 109%, and the relative standard deviations were less than 6%. The method is applicable for the determination of carvedilol and haloperidol in the lake and river water and human plasma samples with recoveries between 98 and 109% and relative standard deviation of less than 9%.

Potentiality of Epoxy-Montmorillonite Composite for Stir-Bar Sorptive Extraction for Determination of Atrazine

Abstract A new low-cost material is presented for the first time, aiming to study the sorption process for the stir-bar sorptive extraction (SBSE) technique. The bars were made using a composition of a commercial epoxy resin and montmorillonite, under different compositions and a final ratio of 70% (epoxy) and 30% (montmorillonite) was employed, providing the best mechanical and chemical resistance. A PTFE support was developed to hold the bars permitting the magnetic stirring, without turbulent behavior even under long times of stirring at 1000 rpm. The bars were employed to study the sorption of the herbicide atrazine (ATZ), and the best extraction conditions were: sample volume 20.0 mL, pH 6.0, extraction time of 15 min, room temperature, stirring speed of 100 rpm, and 10.0% (w v-1) NaCl. This preliminary evaluation suggests that the modified bars could be employed for ATZ sorption, affording close to 71% of ATZ removal, and presented robust characteristics to be used at least 80 times.

Aroma characteristics and volatile compounds of distilled Crystal grape spirits of different alcohol concentrations: wine sprits in the Shangri-La region of China

Abstract Aroma composition is critical to the quality of distilled spirits while the alcohol concentration could have a great effect on the variety and content of aromatic substances. In order to clarify the effect of alcohol concentration on the formation of the aroma composition, volatile compounds in Crystal distilled grape spirits with different alcohol concentrations were analyzed using the Stir bar sorptive extraction (SBSE) technique combined with GC-MS. Characteristic aromas, principal components and odor profiles were also explored. Eighty-six compounds were identified in Crystal distilled grape spirits and 19 compounds were the same for the 4 samples with different alcohol concentrations. The species and contents of esters increased significantly along with the alcohol concentration increasing, while the acid content decreased. No significant change in the volatile alcohol and carbonyl contents was observed, and no terpene was detected in the spirits of 80%vol alcohol content. Fruity was the strongest aroma in the 6 aromatic series of odor, followed by floral and fatty. The 77%vol alcohol distilled grape spirits showed the most fragrant and balanced aroma.

Characterization of Kimchi Flavor with Preconcentration by Head Space Solid-Phase Microextraction and Stir Bar Sorptive Extraction and Analysis by Gas Chromatography-Mass Spectrometry

Kimchi is a traditional fermented vegetable, known for its complex flavor. Herein, we compared compounds related to the kimchi flavor, identified by gas chromatography-mass spectrometry (GC-MS) with the developed solid phase microextraction (SPME) and stir bar sorptive extraction (SBSE) techniques. Although headspace-solid phase microextraction (HS-SPME) detected more volatile compounds than nondestructive-headspace-solid-phase microextraction (ND-HS-SPME), those identified by ND-HS-SPME were considered closely related to the flavor of the intact kimchi. Furthermore, direct immersion-stir bar sorptive extraction (DI-SBSE) detected more volatile and nonvolatile compounds than headspace-stir bar sorptive extraction (HS-SBSE), while more sulfur compounds were identified by HS-SBSE. Therefore, we recommend the use of the HS-SPME method using a divinylbenzene/carboxen/polydimethylsiloxane fiber for identifying compounds related to the kimchi flavor. In addition, principal component analysis showed ND-HS-SPME and HS-SBSE to be closely clustered. Overall, we estimated that the samples obtained via the nondestructive sample preparation emits fewer polar volatile flavor compounds than those obtained using the destructive sample preparation. Considering the findings presented herein, we believe that this study contributes to optimizing the flavor analysis of kimchi and other fermented vegetables.

Validated determination of losartan and valsartan in human plasma by stir bar sorptive extraction based on acrylate monolithic polymer, liquid chromatographic analysis and experimental design methodology

In our previous work, a new monolithic coating based on vinylpyrrolidone-ethylene glycol dimethacrylate polymer was introduced for stir bar sorptive extraction. The formulation of the prepared vinylpyrrolidone-ethylene glycol dimethacrylate monolithic polymer was optimized and the satisfactory quality of prepared coated stir bar was demonstrated. In this work, the prepared stir bar was utilized in combination with ultrasound-assisted liquid desorption, followed by high-performance liquid chromatography with ultraviolet detection for the simultaneous determination of losartan (LOS) and valsartan (VAS) in human plasma samples. In a comparison study, the extraction efficiency of the prepared stir bar was accompanied much higher extraction efficiency than the two commercial stir bars (polydimethylsiloxand and polyacrylate) for both target compounds. In order to improve the desorption efficiency of LOS and VAS, the best values for effective parameters on desorption step were selected systematically. Also, the effective parameters on extraction step were optimized using a Box-Behnken design. Under the optimum conditions, the analytical performance of the proposed method displayed excellent linear dynamic ranges for LOS (24–1000 ng mL−1) and VAS (91–1000 ng mL−1), with correlation coefficients of 0.9998 and 0.9971 and detection limits of 7 and 27 ng mL−1, respectively. The intra- and inter-day recovery ranged from 98 to 117%, and the relative standard deviations were less than 8%. Finally, the proposed technique was successfully applied to the analysis of LOS and VAS at their therapeutic levels in volunteer patient plasma sample. The obtained results were confirmed using liquid chromatography-mass spectrometry. The proposed technique was more rapid than previously reported stir bar sorptive extraction techniques based on monolithic coatings, and exhibited lower detection limits in comparison with similar methods for the determination of LOS and VLS in biological fluids. The obtained results were demonstrated that the lower selectivity of UV in comparison with MS detection was rectified by appropriate sample preparation through proposed extraction method to eliminate as many interfering compounds as possible.

Epoxy resin as a new alternative sorbent phase for stir bar sorptive extraction for the determination of triclosan and methyl-triclosan

ABSTRACTThe main objective of this study is to propose a new sorbent phase based on a commercial epoxy resin, for use as an alternative sorbent in the stir bar sorptive extraction (SBSE) technique. The analytes triclosan (TCS) and methyl-triclosan (MTCS) were selected in order to demonstrate the application of the bars, using some water samples as matrices. The extraction conditions of sample volume, stirring time, pH, temperature and ionic strength were evaluated, and for the back extraction, the bars were sonicated using 1.00 mL of acetonitrile for 10 min. The technique of liquid chromatography using a diode array detector was employed for the quantitation. Analytical curves of between 2.50 and 50.0 μg L−1 with r2 of 0.9894 (TCS) and 0.9933 (MTCS), and limit of detection (LOD) values of 0.6 μg L−1 (TCS) and 2.0 μg L−1 (MTCS) were observed. Recovery values between 100.4% and 121.6% were verified for ultrapure water and between 50.3% and 93.8% for wastewater samples, thereby suggesting the possibility of employing the bars for quantitation of TCS and MTCS in aqueous samples. This is the first time that this resin has been applied without the need for the adhesion of any additional sorbent phase, thereby providing a simple and low-cost method. Another feature is that only eight bars were employed in the entire work, and each bar was used approximately 40 times with the same performance without memory effects.

Analysis of biogenic carbonyl compounds in rainwater by stir bar sorptive extraction technique with chemical derivatization and gas chromatography-mass spectrometry.

Stir bar sorptive extraction is a powerful technique for the extraction and analysis of organic compounds in aqueous matrices. Carbonyl compounds are ubiquitous components in rainwater, however, it is a major challenge to accurately identify and sensitively quantify carbonyls from rainwater due to the complex matrix. A stir bar sorptive extraction technique was developed to efficiently extract carbonyls from aqueous samples following chemical derivatization by O‐(2,3,4,5,6‐pentafluorobenzyl) hydroxylamine hydrochloride. Several commercial stir bars in two sizes were used to simultaneously measure 29 carbonyls in aqueous samples with detection by gas chromatography with mass spectrometry. A 100 mL aqueous sample was extracted by stir bars and the analytes on stir bars were desorbed into a 2 mL solvent solution in an ultrasonic bath. The preconcentration Coefficient for different carbonyls varied between 30 and 45 times. The limits of detection of stir bar sorptive extraction with gas chromatography mass spectrometry for carbonyls (10–30 ng/L) were improved by ten times compared with other methods such as gas chromatography with electron capture detection and stir bar sorptive extraction with high‐performance liquid chromatography and mass spectrometry. The technique was used to determine carbonyls in rainwater samples collected in York, UK, and 20 carbonyl species were quantified including glyoxal, methylglyoxal, isobutenal, 2‐hydroxy ethanal.

Hollow fiber–stir bar sorptive extraction and microwave assisted derivatization of amino acids in biological matrices

A kind of solid phase microextraction configuration combining the principles of hollow fiber solid phase microextraction (HF–SPME) and stir bar sorptive extraction (SBSE) is presented. The main feature of HF–SBSE is the use of microporous hollow fiber acting as the carrier and filter, while a thin stainless steel wire and silica microspheres in the lumen of hollow fiber respectively acting as the magnetic stirrer and the dispersed sorbents for the collection and extraction of the target analytes, thus affording extraction process like SBSE. Moreover, the prepared hollow fiber stir bar was applied to direct microextraction and microwave assisted derivatization with N,O–Bis(trimethylsilyl)trifluroacetamide (BSTFA) of four amino acids in rats’ urine and cerebrospinal fluid followed by gas chromatography mass spectrometric analysis. The limits of detection for four amino acids were found to be in the range of 0.0003–0.017μgmL−1, and all the analytes did not exhibit any lack of fit. The extraction recoveries using HF–SBSE techniques ranged from 71.8% to 102.3%. The results indicated that hollow fiber stir bar sorptive extraction was a promising technique for the enrichment and direct derivatization of analytes extracted from biological matrices without sample clean–up.

Stir bar sorptive extraction coupled with GC/MS applied to honey: optimization of method and comparative study with headspace extraction techniques

The stir bar sorptive extraction (SBSE) techniques, coupled with gas chromatography–mass spectrometry, were successfully applied to the study of Eucalyptus honey’s for the determination of volatile organic compounds (VOCs). An optimization of the extraction method was carried out and the variables, NaCl concentration (used as matrix modifier), and the concentration of honey solution were studied targeting the whole VOCs composition. After the evaluation of the experiments, the best condition for the extraction of honey volatile components was 2 mol/L of NaCl and the more concentrated honey solution (0.5 g of honey per mL of water). Additionally, the results were compared with those obtained by two headspace (HS) techniques, namely solid-phase microextraction (SPME) and dynamic headspace (DHS). SBSE volatiles differ qualitatively and quantitatively from those obtained by the SPME and DHS methods. In any event, the chemical composition of Eucalyptus honey volatiles extracted by all three techniques shows the presence of some typical floral markers. Our results confirm a general trend reported in the literature, which show the higher sensitivity of SBSE in the extraction of less volatile compounds in comparison with HS methods.

Solvent-assisted stir bar sorptive extraction by using swollen polydimethylsiloxane for enhanced recovery of polar solutes in aqueous samples: Application to aroma compounds in beer and pesticides in wine

A novel solvent-assisted stir bar sorptive extraction (SA-SBSE) technique was developed for enhanced recovery of polar solutes in aqueous samples. A conventional PDMS stir bar was swollen in several solvents with log Kow ranging from 1.0 to 3.5 while stirring for 30min prior to extraction. After extraction, thermal desorption – gas chromatography – (tandem) mass spectrometry (TD-GC-(MS/)MS) or liquid desorption – large volume injection (LD-LVI)-GC–MS were performed. An initial study involved investigation of potential solvents for SA-SBSE by weighing of the residual solvent in the swollen PDMS stir bar before and after extraction. Compared to conventional SBSE, SA-SBSE using diethyl ether, methyl isobutyl ketone, dichloromethane, diisopropyl ether and toluene provided higher recoveries from water samples for test solutes with log Kow<2.5. For SA-SBSE using dichloromethane, recoveries were improved by factors of 1.4–4.1, while maintaining or even improving the recoveries for test solutes with log Kow>2.5. The performance of the SA-SBSE method using dichloromethane, diisopropyl ether, and cyclohexane is illustrated with analyses of aroma compounds in beer and of pesticides in wine.

Preparation of a novel sorptive stir bar based on vinylpyrrolidone-ethylene glycol dimethacrylate monolithic polymer for the simultaneous extraction of diazepam and nordazepam from human plasma.

A new monolithic coating based on vinylpyrrolidone-ethylene glycol dimethacrylate polymer was introduced for stir bar sorptive extraction. The polymerization step was performed using different contents of monomer, cross-linker and porogenic solvent, and the best formulation was selected. The quality of the prepared vinylpyrrolidone-ethylene glycol dimethacrylate stir bars was satisfactory, demonstrating good repeatability within batch (relative standard deviation < 3.5%) and acceptable reproducibility between batches (relative standard deviation < 6.0%). The prepared stir bar was utilized in combination with ultrasound-assisted liquid desorption, followed by high-performance liquid chromatography with ultraviolet detection for the simultaneous determination of diazepam and nordazepam in human plasma samples. To optimize the extraction step, a three-level, four-factor, three-block Box-Behnken design was applied. Under the optimum conditions, the analytical performance of the proposed method displayed excellent linear dynamic ranges for diazepam (36-1200 ng/mL) and nordazepam (25-1200 ng/mL), with correlation coefficients of 0.9986 and 0.9968 and detection limits of 12 and 10 ng/mL, respectively. The intra- and interday recovery ranged from 93 to 106%, and the relative standard deviations were less than 6%. Finally, the proposed method was successfully applied to the analysis of diazepam and nordazepam at their therapeutic levels in human plasma. The novelty of this study is the improved polarity of the stir bar coating and its application for the simultaneous extraction of diazepam and its active metabolite, nordazepam in human plasma sample. The method was more rapid than previously reported stir bar sorptive extraction techniques based on monolithic coatings, and exhibited lower detection limits in comparison with similar methods for the determination of diazepam and nordazepam in biological fluids.

교반막대 추출법과 GC-MS/MS를 이용한 수중의 합성 향물질류 분석

A highly sensitive analytical method based on stir bar sorptive extraction (SBSE) technique and gas chromatography/ tandem mass spectrometry (GC-MS/MS) has been developed, allowing the simultaneous multi-analyte determination of 11 synthetic fragrances (SFs) in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 40 mL of water sample at pH 3 and stirred at 1,100 rpm for 120 min. Other SBSE parameters (salt effect and presence of organic solvent) were optimised. The method shows good linearity (coefficients > 0.990) and reproducibility (RSD < 10.9%). The extraction efficiencies were above 83% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1~4.1 ng/L and 6.6~12.9 ng/L, respectively. The developed method offers the ability to detect 11 SFs at ultra-low concentration levels with only 40 mL of sample volume. Matrix effects in tap water, river water, wastewater treatment plant (WWTP) final effluent water and seawater were investigated and it was shown that the method is suitable for the analysis of trace level of 11 SFs. The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.

교반막대 추출법과 GC/MS-MS를 이용한 수중의 자외선 차단제 분석

A highly sensitive analytical method based on stir bar sorptive extraction (SBSE) technique and gas chromatography/tandem mass spectrometry (GC/MS-MS) has been developed, allowing the simultaneous multi-analyte determination of seven UV filters in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 40 mL of water sample at pH 3 and stirred at 1,100 rpm for 120 min. Other SBSE parameters (salt effect and presence of organic solvent) were optimised. The method shows good linearity (coefficients > 0.990) and reproducibility (RSD < 12.9%). The extraction efficiencies were above 84% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1∼8.6 ng/L and 6.8∼27.5 ng/L, respectively. The developed method offers the ability to detect 8 UV filters at ultra-low concentration levels with only 40 mL of sample volume. Matrix effects in tap water, river water, wastewater treatment plant (WWTP) final effluent water and seawater were investigated and it was shown that the method is suitable for the analysis of trace level of 7 UV filters except of benzophenone (BP). The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.