Fully automated in-tube solid-phase microextraction for liquid samples coupled to gas chromatography

An online device is described in which analytes are extracted from a liquid sample by means of in-tube solid-phase microextraction (in-tube SPME), pulse released by rapid heating, and transferred to a gas chromatograph in a fully automated way. Switching of the sample and gas flows as well as the heating of the extraction tube and the valves is controlled by a remote computer system. Results obtained for river water and for aqueous standard solutions of phenanthrene are presented and are compared to the performance of standard SPME.     

毛细管内固相微萃取-微柱高效液相色谱在线联用

介绍了一种毛细管内固相微萃取器和微柱高效液相色谱在线联用方法.该萃取器替代定量管直接安装在进样阀上,无需特制接口和专门洗脱液.用10 cm×0.32 mm i.d.×0.6 μm交联OV-1作为萃取柱,对0.4 mL样品萃取富集,用流动相为洗脱液,在15 cm×0.32 mm i.d. 微柱液相色谱分析,该方法使检测灵敏度比直接进样提高10～20倍.对蒽的检出限为0.4 μg/L.     

Strengths and weaknesses of in-tube solid-phase microextraction: A scoping review

In-tube solid-phase microextraction (in-tube SPME or IT-SPME) is a sample preparation technique which has demonstrated over time its ability to couple with liquid chromatography (LC), as well as its advantages as a miniaturized technique. However, the in-tube SPME perspectives in the forthcoming years depend on solutions that can be brought to the environmental, industrial, food and biomedical analysis. The purpose of this scoping review is to examine the strengths and weaknesses of this technique during the period 2009 to 2015 in order to identify research gaps that should be addressed in the future, as well as the tendencies that are meant to strengthen the technique.     

Temperature-response polymer coating for in-tube solid-phase microextraction coupled to high-performance liquid chromatography

The silica nanoparticle (SiO₂ NP)-deposited capillary fabricated by liquid phase deposition (LPD) was bonded by 3-(triethoxysilyl) propyl methacrylate and then modified with poly(N-isopropylacrylamide) (PNIPAAm) by polymerization. The resulting PNIPAAm modified SiO₂ NP-deposited capillary was applied to in-tube solid-phase microextraction coupled to high-performance liquid chromatography (in-tube SPME-HPLC). To investigate the extraction performance of the prepared capillary, diethylstilbestrol (DES) with moderate polarity was selected as the model analyte. Results demonstrate that PNIPAAm modified SiO₂ NP-deposited capillary exhibited obvious temperature responsive character. Finally, the PNIPAAm modified SiO₂ NP-deposited capillary was applied to the analysis of three synthetical estrogens from milk samples. The detection limit of the method was found to be in the range 1.2-2.2 ng/g, and recovery was 71.7-98.9% with relative standard deviations in the range of 2.8-12.6%.     

Determination of fluoxetine and norfluoxetine enantiomers in human plasma by polypyrrole-coated capillary in-tube solid-phase microextraction coupled with liquid chromatography-fluorescence detection

A sensitive, selective, and reproducible in-tube polypyrrole-coated capillary (PPY) solid-phase microextraction and liquid chromatographic method for fluoxetine and norfluoxetine enantiomers analysis in plasma samples has been developed, validated, and further applied to the analysis of plasma samples from elderly patients undergoing therapy with antidepressants. Important factors in the optimization of in-tube SPME efficiency are discussed, including the sample draw/eject volume, draw/eject cycle number, draw/eject flow-rate, sample pH, and influence of plasma proteins. Separation of the analytes was achieved with a Chiralcel OD-R column and a mobile phase consisting of potassium hexafluorophosphate 7.5 mM and sodium phosphate 0.25 M solution, pH 3.0, and acetonitrile (75:25, v/v) in the isocratic mode, at a flow rate of 1.0 mL/min. Detection was carried out by fluorescence absorbance at Ex/Em 230/290 nm. The multifunctional porous surface structure of the PPY-coated film provided high precision and accuracy for enantiomers. Compared with other commercial capillaries, PPY-coated capillary showed better extraction efficiency for all the analytes. The quantification limits of the proposed method were 10 ng/mL for R- and S-fluoxetine, and 15 ng/mL for R- and S-norfluoxetine, with a coefficient of variation lower than 13%. The response of the method for enantiomers is linear over a dynamic range, from the limit of quantification to 700 ng/mL, with correlation coefficients higher than 0.9940. The in-tube SPME/LC method can therefore be successfully used to analyze plasma samples from ageing patients undergoing therapy with fluoxetine.     

Automated analysis of lidocaine and its metabolite in plasma by in-tube solid-phase microextraction coupled with LC-UV for pharmacokinetic study

A sensitive, selective, and reproducible in-tube solid-phase microextraction and liquid chromatographic (in-tube SPME/LC-UV) method for determination of lidocaine and its metabolite monoethylglycinexylidide (MEGX) in human plasma has been developed, validated, and further applied to pharmacokinetic study in pregnant women with gestational diabetes mellitus (GDM) subjected to epidural anesthesia. Important factors in the optimization of in-tube SPME performance are discussed, including the draw/eject sample volume, draw/eject cycle number, draw/eject flow rate, sample pH, and influence of plasma proteins. The limits of quantification of the in-tube SPME/LC method were 50 ng/mL for both metabolite and lidocaine. The interday and intraday precision had coefficients of variation lower than 8%, and accuracy ranged from 95 to 117%. The response of the in-tube SPME/LC method for analytes was linear over a dynamic range from 50 to 5000 ng/mL, with correlation coefficients higher than 0.9976. The developed in-tube SPME/LC method was successfully used to analyze lidocaine and its metabolite in plasma samples from pregnant women with GDM subjected to epidural anesthesia for pharmacokinetic study.     

Determination of polycyclic aromatic hydrocarbons in food samples by automated on-line in-tube solid-phase microextraction coupled with high-performance liquid chromatography-fluorescence detection

A simple and sensitive automated method, consisting of in-tube solid-phase microextraction (SPME) coupled with high-performance liquid chromatography-fluorescence detection (HPLC-FLD), was developed for the determination of 15 polycyclic aromatic hydrocarbons (PAHs) in food samples. PAHs were separated within 15 min by HPLC using a Zorbax Eclipse PAH column with a water/acetonitrile gradient elution program as the mobile phase. The optimum in-tube SPME conditions were 20 draw/eject cycles of 40 μL of sample using a CP-Sil 19CB capillary column as an extraction device. Low- and high-molecular weight PAHs were extracted effectively onto the capillary coating from 5% and 30% methanol solutions, respectively. The extracted PAHs were readily desorbed from the capillary by passage of the mobile phase, and no carryover was observed. Using the in-tube SPME HPLC-FLD method, good linearity of the calibration curve (r > 0.9972) was obtained in the concentration range of 0.05–2.0 ng/mL, and the detection limits (S/N = 3) of PAHs were 0.32–4.63 pg/mL. The in-tube SPME method showed 18–47 fold higher sensitivity than the direct injection method. The intra-day and inter-day precision (relative standard deviations) for a 1 ng/mL PAH mixture were below 5.1% and 7.6% (n = 5), respectively. This method was applied successfully to the analysis of tea products and dried food samples without interference peaks, and the recoveries of PAHs spiked into the tea samples were >70%. Low-molecular weight PAHs such as naphthalene and pyrene were detected in many foods, and carcinogenic benzo[a]pyrene, at relatively high concentrations, was also detected in some black tea samples. This method was also utilized to assess the release of PAHs from tea leaves into the liquor.     

Analysis of heterocyclic amines in hair by on-line in-tube solid-phase microextraction coupled with liquid chromatography−tandem mass spectrometry

Mutagenic and carcinogenic heterocyclic amines (HCAs) are formed during heating of various proteinaceous foods, but human exposure to HCAs has not yet been elucidated in detail. To assess long-term exposure to HCAs, we developed a simple and sensitive method for measuring HCAs in hair by automated on-line in-tube solid-phase microextraction (SPME) coupled with liquid chromatography–tandem mass spectrometry (LC–MS/MS). Using a Zorbax Eclipse XDB-C8 column, 16 HCAs were analyzed within 15 min. The optimum in-tube SPME conditions were 20 draw/eject cycles of 40 μL sample at a flow rate of 200 μL min⁻¹ using a Supel-Q PLOT capillary column as an extraction device. The extracted HCAs were easily desorbed from the column by passage of the mobile phase, with no carryover observed. This in-tube SPME LC–MS/MS method showed good linearity for HCAs in the range of 10–2000 pg mL⁻¹, with correlation coefficients above 0.9989 (n = 18), using stable isotope-labeled HCA internal standards. The detection limits (S/N = 3) of 14 HCAs except for MeAαC and Glu-P-1 were 0.10–0.79 pg mL⁻¹. This method was successfully utilized to analyze 14 HCAs in hair samples without any interference peaks, with quantitative limits (S/N = 10) of about 0.17–1.32 pg mg⁻¹ hair. Using this method, we evaluated the exposure to HCAs in cigarette smoke and the suitability of using hair HCAs as exposure biomarkers.     

管内固相微萃取-气相色谱法联用在线测定水中有机物

将管内固相微萃取与气相色谱法结合，建立了水中痕量有机物的在线分析装置。采用毛细管气相色谱柱作为萃取柱，水样中的分析物在萃取柱中被萃取浓缩，溶剂解吸后的样品通过阀切换和柱内进样技术直接由载气携带进入气相色谱柱。采用OV-1萃取柱，对水样中的5种芳烃的富集倍数为34～85。     

Selective capillary coating materials for in-tube solid-phase microextraction coupled to liquid chromatography to determine drugs and biomarkers in biological samples: A review

In-tube solid-phase microextraction (in-tube SPME) coupled with high performance liquid chromatography (HPLC) or liquid chromatography coupled to mass spectrometry (LC-MS) successfully determines drugs or biomarkers in biological samples by direct sample injection or by simple sample treatment. This technique uses a capillary column as extraction device. Several capillaries (wall-coated open tubular, sorbent-packed, porous monolithic rods, or fiber-packed) with unique phases have been developed and evaluated, aiming to improve the efficiency and selectivity of the in-tube SPME-LC technique. This review describes new developments and applications occurred in recent years, and discusses future trends with emphasis on new extraction devices and current technology used for the synthesis of selective sorbents for bioanalysis, such as (i) polypyrrole, (ii) restricted-access materials, (iii) immunosorbents, (iv) molecular imprinting polymers, (v) monolithic polymers, and (vi) bi-functional materials.     

Determination of fluoroquinolones in eggs using in-tube solid-phase microextraction coupled to high-performance liquid chromatography

A simple, rapid, and sensitive method using in-tube solid-phase microextraction (in-tube SPME) based on poly(methacrylic acid–ethylene glycol dimethacrylate) (MAA–EGDMA) monolith coupled to HPLC with fluorescence and UV detection was developed for the determination of five fluoroquinolones (FQs). Ofloxacin (OFL), norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENRO), and sarafloxacin (SARA) can be enriched and determined in the spiked eggs and albumins. CIP/ENRO in eggs and albumins of ENRO-treated hens were also studied using the proposed method. Only homogenization, dilution, and centrifugation were required before the sample was supplied to the in-tube microextraction, and no organic solvents were consumed in the procedures. Under the optimized extraction conditions, good extraction efficiency for the five FQs was obtained with no matrix interference in the process of extraction and the subsequent chromatographic separation. The detection limits (S/N=3) were found to be 0.1–2.6 ng g⁻¹ and 0.2–2.4 ng g⁻¹ in whole egg and egg albumin, respectively. Good linearity could be achieved over the range 2–500 ng mL⁻¹ for the five FQs with regression coefficients above 0.9995 in both whole egg and albumin. The reproducibility of the method was evaluated at three concentration levels, with the resulting relative standard deviations (RSDs) less than 7%. The method was successfully applied to the analysis of ENRO and its primary metabolite CIP in the eggs and albumins of ENRO-treated hens.     

固相微萃取-气相色谱/质谱联用分析室内空气中的苯系物

自制了一种固相微萃取采样装置,建立了固相微萃取-气相色谱/质谱(SPME-GC/MS)联用测定室内空气中苯系物的分析方法。方法的线性范围为1~300μg/m3,检出限为0.1~0.3μg/m3,RSD(n=6)3.2%~15%。采用该方法研究了广州市内20户新装修民居中苯、甲苯、乙苯、对二甲苯和1,3,5-三甲苯的含量及分布,并探讨了苯系物的来源。     

Liquid-phase deposition of silica nanoparticles into a capillary for in-tube solid-phase microextraction coupled with high-performance liquid chromatography

A silica nanoparticle (NP)-deposited capillary fabricated by liquid-phase deposition (LPD) and modified with octadecyl groups was introduced for in-tube solid-phase microextraction coupled to high-performance liquid chromatography with UV detection (in-tube SPME–HPLC). The resultant capillary (60 cm × 50 μm I.D.) was demonstrated to be of higher extraction capacity by comparing with an octadecyl-grafted bare capillary and an octadecyl-grafted silica-coated capillary that was prepared by sol–gel chemistry. Two groups of compounds, endocrine disruptors and polycyclic aromatic hydrocarbons, were used as model analytes to further evaluate extraction capacity of the silica NP-deposited capillary, and its reproducibility and stability was also investigated. The extraction time profiles were monitored for all the chemicals, and their limits of detection were calculated to be in the range of 0.42–0.78 and 0.034–0.19 ng/mL with RSD values of peak area less than 4.6%.     

毛细管固相微萃取-超高效液相色谱-串联质谱法测定血浆中麻醉精神药物

提出了毛细管固相微萃取-超高效液相色谱-串联质谱法测定血浆中麻醉精神药物含量的方法。取样品1mL,加硼砂缓冲液2mL混匀,离心,上清液转入注射器针管中,接内壁固定有DB-5毛细管色谱柱的不锈钢针头,置于注射泵上以200μL·min-1流量排出样品,用1mL水冲洗针头,再用50μL乙腈洗脱2min。以梯度洗脱-电喷雾正离子源-多反应监测测定洗脱液中药物成分。16种药物的检出限小于10μg·L-1,18种药物的检出限在10~50μg·L-1之间,3种药物的检出限不小于77μg·L-1,5种药物未能检出。血浆中37种药物回收率在4.0%~93.5%之间,相对标准偏差(n=6)在0.80%~13%之间。76起案例样品中检出31例。     

Evaluating polymer monolith in-tube solid-phase microextraction coupled to liquid chromatography/quadrupole time-of-flight mass spectrometry for reliable quantification and confirmation of quinolone antibacterials in edible animal food

A simple, rapid, and sensitive method is presented to determine seven trace quinolone antibacterials simultaneously in milk, egg, chicken and fish. This method is based on the combination of polymer monolith in-tube solid-phase microextraction with liquid chromatography and electrospray ionization quadrupole time-of-flight mass spectrometry (LC/ESI-QTOF-MS). LC/ESI-QTOF-MS offers the capability of unequivocal identification of target compounds from complex matrices, as well as the possibility of quantitation at low-level concentrations in real samples. The extraction was performed with a poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic column. Under the optimized extraction conditions, good extraction efficiencies for the targets were obtained with no matrix interference in the subsequent LC/ESI-QTOF-MS. Good linearities were obtained for seven quinolones with the correlation coefficients (R) above 0.9951. The limits of detection (S/N = 3) for seven quinolones were found to be 0.3–1.2 ng/g in egg, 0.2–3.0 ng/mL in milk, 0.2–0.7 ng/g in chicken and 0.2–1.0 ng/g in fish. The recoveries of quinolones spiked in four different matrices ranged from 80.2 to 115.0%, with relative standard deviations less than 14.5%. The developed method was applied for the determination of quinolone residues in animal-producing food, and the positive samples were confirmed with high number of identification points (IPs) according to the IP system defined by the European Union (Commission Decision 2002/657/EC).     

Determination of fluoroquinolones in environmental waters by in-tube solid-phase microextraction coupled with liquid chromatography-tandem mass spectrometry

We developed a sensitive and useful method for the determination of five fluoroquinolones (FQs), enoxacin, ofloxacin, ciprofloxacin, norfloxacin, and lomefloxacin in environmental waters, using a fully automated method consisting of in-tube solid-phase microextraction (SPME) coupled with liquid chromatography-tandem mass spectrometry (LC/MS/MS). These compounds were analysed within 7 min by high-performance liquid chromatography (HPLC) using a CAPCELL PAK C8 column and aqueous ammonium formate (pH 3.0, 5 mM)/acetonitrile (85/15, v/v) at a flow rate of 0.2 mL/min. Electrospray ionization conditions in the positive ion mode were optimized for MS/MS detection. In order to optimize the extraction of FQs, several in-tube SPME parameters were examined. The optimum in-tube SPME conditions were 20 draw/eject cycles of 40 μL of sample at a flow-rate of 150 μL/min, using a Carboxen 1010 PLOT capillary column as an extraction device. The extracted compounds were easily desorbed from the capillary by passage of the mobile phase. Using the in-tube SPME LC/MS/MS method, good linearity of the calibration curve (r ≥ 0.997) was obtained in the concentration range from 0.1 to 10 ng/mL for all compounds examined. The limits of detection (S/N = 3) of the five FQs ranged from 7 to 29 pg/mL. The in-tube SPME method showed 60-94-fold higher sensitivity than the direct injection method (5 μL injection). This method was applied successfully to the analysis of environmental water samples without any other pretreatment and interference peaks. Several surface waters and wastewaters were collected from the area around Asahi River, and ofloxacin was detected in wastewater samples of a sewage treatment plant and other two hospitals at 17.5-186.2 pg/mL. The recoveries of FQs spiked into river water were above 81% for a 0.1 or 0.2 ng/mL spiking concentration, and the relative standard deviations were below 1.9-8.6%.     

Determination of perfluorooctanoic acid and perfluorooctane sulfonate by automated in-tube solid-phase microextraction coupled with liquid chromatography-mass spectrometry

We have developed a simple, rapid, and sensitive method for the determination of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) by on-line in-tube solid-phase microextraction (SPME) coupled with liquid chromatography-mass spectrometry (LC-MS). PFOA and PFOS were separated within 10 min by high-performance liquid chromatography using an Inertsil ODS-3 column and 10 mM ammonium acetate/methanol (35/65, v/v) as a mobile phase at a flow rate of 0.25 mL min⁻¹. Electrospray ionization conditions in the negative ion mode were optimized for MS detection of PFOA and PFOS. The optimum in-tube SPME conditions were 20 draw/eject cycles with a sample size of 40 μL using a CP-Pora PLOT amine capillary column as the extraction device. The extracted compounds could be desorbed easily from the capillary by passage of the mobile phase, and no carryover was observed. Using the in-tube SPME LC-MS method, good linearity of the calibration curve (r = 0.9990 for PFOA, r = 0.9982 for PFOS) was obtained in the range of 0.05-5 ng mL⁻¹ each compound. The detection limits (S/N = 3) for PFOA and PFOS were 1.5 and 3.2 pg mL⁻¹, respectively. The method described here showed about 100-fold higher sensitivity than the direct injection method. The within-day and between-day precisions (relative standard deviations) were below 3.7 and 6.0%, respectively. This method was applied successfully to the analysis of PFOA and PFOS in environmental water samples and to the elution test from a Teflon^®-coated frying pan without interference peaks. The recoveries of PFOA and PFOS spiked into river samples were above 81%, and PFOA was detected at pg mL⁻¹ levels in environmental water samples and eluate from the frying pan.     

管内硼亲和固相微萃取-高效液相色谱全自动在线联用检测茶饮料中的顺式二羟基化合物

自动化联用分析技术对于降低人力强度、提高效率和保证数据重现性等具有重要意义。硼亲和固相微萃取(BA-SPME)是近十年出现的用于富集顺式二羟基化合物的独特工具,但BA-SPME与高效液相色谱(HPLC)的自动化在线联用还未见报道。该文报道了一种新颖的管内BA-SPME-HPLC全自动在线联用方法,用于分析茶饮料中的顺式二羟基化合物。该自动化在线联用方法利用自动进样器通过六通阀的切换实现流路连接。制备了管内BA-SPME毛细管,考察了涂层柱的柱容量,并对其形貌进行了表征,考察并优化了影响实际样品分离效果的因素。最后,利用该联用方法对3种不同品牌的茶饮料进行了分析,并对沏茶温度对茶水中顺式二羟基化合物含量的影响进行了评价。     

A sensitive LC‐MS/MS method for the simultaneous determination of amoxicillin and ambroxol in human plasma with segmental monitoring

Amoxicillin (AMO) degrades in plasma at room temperature and readily undergoes hydrolysis by the plasma amidase. In this paper, a novel, rapid and sensitive LC‐MS/MS method operated in segmental and multiple reaction monitoring has been developed for the simultaneous determination of amoxicillin and ambroxol in human plasma. The degradation of amoxicillin in plasma was well prevented by immediate addition of 20 μL glacial acetic acid to 200 μL aliquot of freshly collected plasma samples before storage at ?80°C. The sensitivity of the method was improved with segmental monitoring of the analytes, and lower limits of quantitation of 0.5 ng/mL for ambroxol and 5 ng/mL for amoxicillin were obtained. The sensitivity of our method was five times better than those of the existing methods. Furthermore, the mass response saturation problem with amoxicillin was avoided by diluting the deproteinized plasma samples with water before injection into the LC‐MS/MS system. The method was successfully employed in a pharmacokinetic study of the compound amoxicillin and ambroxol hydrochloride tablets. Copyright © 2012 John Wiley & Sons, Ltd.     

乳腺癌代谢物组模式特征发现方法及HPLC/M S/M S分析

提出一种基于单独最优特征组合和BP神经网络的代谢物组模式特征发现方法,并用其寻找到尿样中与乳腺癌最为相关的4种核苷,组成一组特异性检测参数.经HPLC/MS/MS联用法鉴定,它们是乳清酸核苷、1-甲酰化腺苷、S-腺苷-L-蛋氨酸及N²-甲酰化鸟苷.将这4种核苷作为输入变量,用BP神经分类网络建立乳腺癌诊断模型.留一法交叉验证和独立验证结果表明,该模型预测准确率达到90%以上.