Novel unbreakable solid-phase microextraction fiber by electrodeposition of silica sol-gel on gold

A new technique for preparation of an unbreakable solid-phase microextraction (SPME) fiber, using sol-gel technology is developed. Primarily, an ultrathin two-dimensional intermediate film was prepared by hydrolysis of 3-(trimethoxysilyl)-1-propanthiol self-assembled monolayer grafted onto gold, then a stationary phase by electrodeposition of 3-(trimethoxysilyl)propylmethacrylate as a precursor, tetramethyl orthosilicate and polyethylene glycol as a coating polymer was produced. The scanning electron microscopy images revealed that the new fiber exhibits a rather porous and homogenous surface. The thermal stability of the fabricated fiber was investigated by thermogravimetric analysis. The applicability of the prepared fiber coating in conjunction with gas chromatography-mass spectrometry was examined by SPME of polycyclic aromatic hydrocarbons, as model analytes, from aquatic media. An extraction time of 20 min at 50 °C gave maximum peak areas when NaCl, 15% was added to the aqueous samples. Limits of detection were in the range of 0.01-0.02 ng/mL and relative standard deviation values were in the range of 4-16% at 1 ng/mL. The developed method was successfully applied for the analysis of real water samples while the relative recovery percentage was in the range of 102-118%.     

Emulsification liquid phase microextraction followed by on-line phase separation coupled to high performance liquid chromatography

An emulsification liquid phase microextraction followed by on-line phase separation coupled to high performance liquid chromatography (HPLC) is introduced based on a novel idea for the separation of dispersed organic phase from aqueous phase. In this method, the dispersed organic extraction phase was filtered using an in-line filter and it was separated from the water sample. The new approach is simple and, in addition to improving some limitations of the conventional emulsification liquid phase microextraction, eliminates the need for centrifugation in the phase separation step.     

Ionic liquid mediated sol-gel sorbents for hollow fiber solid-phase microextraction of pesticide residues in water and hair samples

An ionic liquid mediated sol-gel sorbents for hollow fiber solid-phase microextraction (HF-SPME) was developed for extraction of the pesticides: diazinon, fenitrothion, malathion, fenvalerate, phosalone and tridemorph from human hair and water samples. The analytes were subsequently analyzed with high performance liquid chromatography and diode array detection (HPLC-DAD). Preliminary experiments were carried out in order to study experimental conditions for pesticides' extraction from spiked hair and water samples with HF-SPME using hollow fiber-supported ionic liquid mediated sol-gel sorbent. The sol-gel nanocomposites were reinforced with nanoparticles such as carboxylic functionalized multi-walled carbon nanotubes (COOH-MWCNTs), amino functionalized multi-walled carbon nanotubes (NH(2)-MWCNTs), nano SiO(2), nano TiO(2) and nano MgO comparatively to promote extraction efficiency. In this device, the innovative solid sorbents were developed by the sol-gel method via the reaction of tetraethylorthosilicate (TEOS) with 2-amino-2-hydroxymethyl-propane-1,3-diol (TRIS). In the basic condition (pH 10-11), the gel growth process in the presence of ionic liquid and nanoparticles was initiated. Then, the sol was injected into a polypropylene hollow fiber segment for in situ gelation process. Parameters affecting the efficiency of HF-SPME were thoroughly investigated. Linearity was observed over a range of 0.01-25,000 ng/mL with detection limits between 0.004 and 0.095 ng/mL for the pesticides in the aqueous matrices and 0.003-0.080 ng/mL in the hair matrices. The relative recoveries in the real samples ranged from 82.0% to 94.0% for the pesticides store seller's hair and the work researchers' hair. Results are showing the great possibilities of HF-SPME-HPLC-PDA for analysis of pesticides in biological and environmental samples.     

Determination of urinary 8-hydroxy-2′-deoxyguanosine by capillary electrophoresis with molecularly imprinted monolith in-tube solid phase microextraction

<正>Urinary 8-hydroxy-2'-deoxyguanosine(8-OHdG) is an excellent marker of oxidative DNA damage.In this study,employing guanosine as dummy template a novel molecularly imprinted(MIP) monolithic capillary column had been synthesized,and that was used as medium of in-tube solid phase microextraction(SPME).Coupled with capillary electrophoresis-electrochemical detection(CE-ECD),the system of extraction and detection of 8-OHdG in urinary sample had been developed.Because of its greater phase ratio combined with convective mass transfer and inherent selectivity,the MIP monolithic column exhibited high extraction efficiency on target analyte with the limit of detection(LOD) and quantity(LOQ) reached 2.6 nmol/L(S/N = 3) and 8.6 nmol/L(S/N= 10),respectively.The linear range was from 10 nmol/L to 1.5μmol/L(r = 0.9999) with relative standard deviation(RSD) 3.7%for peak current,and 0.5%for migration time,and the average recovery of spiked 20-200 nmol/L 8-OHdG was 85%±3.5%(n = 6).This highly sensitive method was applied to analysis of 8-OHdG in urinary samples from healthy volunteers,coking plant workers and lung cancer patients.     

Ionic liquid-mediated bis[(3-methyldimethoxysilyl)propyl] polypropylene oxide-based polar sol–gel coatings for capillary microextraction

Two ionic liquids (IL), namely, 1-methyl-3-octylimidazolium chloride (MOIC) and trihexyltetradecylphosphonium tetrafluoroborate (TTPT) were used to prepare polar and nonpolar sol–gel coatings for capillary microextraction (CME). Bis[(3-methyldimethoxysilyl)propyl] polypropylene oxide (BMPO), containing sol–gel active terminal methoxysilyl groups and polar propylene oxide repeating units, was used to prepare polar sol–gel hybrid organic–inorganic coatings. Hydroxy-terminated poly(dimethyl-co-diphenylsiloxane) was used as the sol–gel active organic component for nonpolar sol–gel hybrid coatings. Compared to a sol–gel BMPO coating prepared without IL, the sol–gel BMPO coatings prepared with the use of both of these ILs provided more efficient extraction as is evidenced by more pronounced GC peak areas. The MOIC-mediated sol–gel BMPO coating provided larger GC peak areas compared to the TTPT-mediated sol–gel BMPO coating. Scanning electron microscopy results suggested that MOIC provided a more porous morphology of the sol–gel BMPO extraction media compared to that prepared with TTPT. Thus, individual ILs can affect the porosity of sol–gel materials to different degrees. Overall, the sol–gel BMPO coating prepared with the ILs could extract nonpolar to polar analytes directly from aqueous samples. Detection limits were on the order of nanograms per liter (1.9–330.5 ng/L) depending on the analyte class. Furthermore, the MOIC-mediated sol–gel BMPO coating demonstrated high thermal stability (330 °C), solvent resistance, and fast extraction equilibrium (10–15 min) for polar and moderately polar analytes.     

On-line analysis of carbonyl compounds with derivatization in aqueous extracts of atmospheric particulate PM10 by in-tube solid-phase microextraction coupled to capillary liquid chromatography

A new device for carbonyl compounds based on coupling on-line and miniaturizing both, sample pretreatment and chromatographic separation, is reported. Two capillary columns, a GC capillary column (95% methyl-5% phenyl substituted backbone, 70 cm × 0.32 mm i.d., 3 μm film thickness) in the injection valve for in-tube solid-phase microextraction (IT-SPME) and a Zorbax SB C18 (150 mm × 0.5 mm i.d., 5 μm particle diameter) LC capillary column were employed. Different combinations of IT-SPME and derivatization using 2,4-dinitrophenylhydrazine (DNPH) were examined for mixtures containing 15 carbonyl compounds (aliphatic, aromatic and unsaturated aldehydes and ketones). A screening analysis of aqueous extracts of atmospheric particulate PM(10) was carried out. Moreover, the possibility of coupling IT-SPME and conventional liquid chromatography is also tested. Derivatization solution and IT-SPME coupled to capillary liquid chromatography provided the best results for achieving the highest sensitivity for carbonyl compounds in atmospheric particulate analysis. Detection limits (LODs) using a photodiode array detector (DAD) were ranged from 30 to 198 ng L(-1), improving markedly those LODs reported by conventional SPME-LC-DAD.     

Sol-gel approach to in situ creation of high pH-resistant surface-bonded organic-inorganic hybrid zirconia coating for capillary microextraction (in-tube SPME)

A novel zirconia-based hybrid organic-inorganic sol-gel coating was developed for capillary microextraction (CME) (in-tube SPME). High degree of chemical inertness inherent in zirconia makes it very difficult to covalently bind a suitable organic ligand to its surface. In the present work, this problem was addressed from a sol-gel chemistry point of view. Principles of sol-gel chemistry were employed to chemically bind a hydroxy-terminated silicone polymer (polydimethyldiphenylsiloxane, PDMDPS) to a sol-gel zirconia network in the course of its evolution from a highly reactive alkoxide precursor undergoing controlled hydrolytic polycondensation reactions. A fused silica capillary was filled with a properly designed sol solution to allow for the sol-gel reactions to take place within the capillary for a predetermined period of time (typically 15-30 min). In the course of this process, a layer of the evolving hybrid organic-inorganic sol-gel polymer got chemically anchored to the silanol groups on the capillary inner walls via condensation reaction. At the end of this in-capillary residence time, the unbonded part of the sol solution was expelled from the capillary under helium pressure, leaving behind a chemically bonded sol-gel zirconia-PDMDPS coating on the inner walls. Polycyclic aromatic hydrocarbons, ketones, and aldehydes were efficiently extracted and preconcentrated from dilute aqueous samples using sol-gel zirconia-PDMDPS coated capillaries followed by thermal desorption and GC analysis of the extracted solutes. The newly developed sol-gel hybrid zirconia coatings demonstrated excellent pH stability, and retained the extraction characteristics intact even after continuous rinsing with a 0.1 M NaOH solution for 24 h. To our knowledge, this is the first report on the use of a sol-gel zirconia-based hybrid organic-inorganic coating as an extraction medium in solid phase microextraction (SPME).     

An in-tube SPME device for the selective determination of chlorophyll a in aquatic systems

We report a new device for the estimation of the content of chlorophyll a pigment in water samples as an indicator of water quality. The extraction of the pigment from water was also optimized. 10 mL of water was filtered through a nylon filter (45 μm pore size and 13 mm of diameter), after the chlorophylls were dissolved by immersing the filter in 1 mL of a low non-hazardous solvent as ethanol. An in-valve in-tube SPME device coupled to capillary liquid chromatography with diode array detection was designed. A capillary column of 70 cm in length (0.32 mm i.d. coated with 5% diphenyl-95% polydimethylsiloxane, 3 μm coating thickness) was used as the loop of the injection valve for preconcentration and a Zorbax SB C₁₈ (SiO₂-based) 150 mm × 0.5 mm i.d., 5 μm column (Agilent) was used as analytical column. The achieved detection limit was 0.05 μg L⁻¹ and the working range of concentrations was 0.1-1 μg L⁻¹. % RSD values between 2 and 11 were obtained. Chlorophyll a in several water matrices was determined with good results in presence of other pigments such as chlorophyll b, pheophytin a and pheophytin b.     

聚苯胺/二氧化钛纳米管固相微萃取纤维的组装及应用

以钛丝表面原位阳极氧化生成的二氧化钛纳米管为基体,通过电聚合苯胺组装得到新型聚苯胺包覆二氧化钛复合纳米管阵列固相微萃取纤维。实验讨论了无机酸介质、苯胺浓度和氧化电压对电聚合苯胺的影响,经过对纤维表面形貌和元素成分的分析,得到最佳的纤维涂层条件:电解液组成为1 mol/L的H₂SO₄-0.5 mol/L的苯胺,聚合电压10 V,氧化时间60 min。采用所制备的纤维与高效液相色谱联用萃取水样中的紫外线吸收剂并优化萃取条件,固相微萃取条件如下:萃取时间40 min,解吸时间4 min,萃取温度40℃,搅拌速率600 r/min,样品溶液中不加NaCl。同时对环境水样中的目标物分析测定,并做加标试验,目标分析物的平均回收率为78.2%～118%,相对标准偏差为4.4%～8.9%。该方法简便、灵敏、准确,适用于环境水样中紫外线吸收剂的快速测定。     

基于溶胶凝胶技术的在线固相萃取与高效液相色谱联用测定饮用水中的雌激素残留

建立了固相萃取与高效液相色谱在线联用测定水样中3种雌激素(己烯雌酚、己烷雌酚、双烯雌酚)痕量残留的方法。以溶胶凝胶技术合成的聚合物为固相萃取材料,对水样中的雌激素进行萃取富集,考察了样品溶液不同pH、上样流速及洗脱溶剂等条件对合成材料富集效果的影响。结果表明,在优化的条件下,该方法对3种雌激素的检出限(S/N=3)为0.07~0.13 μg/L,样品中的加标回收率为82.31%~99.43%,相对标准偏差(RSD)为1.61%~7.15%。方法简便可靠,适用于饮用水中雌激素的痕量残留检测。     

Simultaneous HPLC determination of phenylurea herbicides and their corresponding anilines in water after on-line preconcentration

On-line preconcentration on a short C₁₈ column, prior to HPLC with UV and electrochemical detection, has been used for determination of some phenylurea herbicides and their possible degradation products, substituted anilines, in water samples. With electrochemical detection the detection limit at a signal-to-noise ratio of 3 was 5 ppt for 4-chloroaniline and 4-bromoaniline and 7 ppt for 3,4-dichloroaniline; with UV detection the detection limit was ca 300 ppt for all analytes.     

溶胶-凝胶杂化整体柱修饰及在多环芳烃检测中的应用

利用点击反应对含叠氮基的溶胶-凝胶整体柱进行了表面修饰,制备了C₆-硅胶杂化整体萃取柱。实验以多环芳烃为分析对象,考察了制备和修饰条件对萃取效率的影响,在优化的条件下,新制备的整体柱对萘、菲、芘和苯并[a]芘的萃取富集倍数分别达到95.9、114.2、103.2和57.8。萃取实验的日内和日间精密度(RSD)分别小于5.5%(n=8)和7.3%(n=10)。建立的管内固相微萃取-高效液相色谱检测16种常见多环芳烃方法的检出限(S/N=3)达到0.08~3.72 μg/L,定量限(S/N=10)达到0.26~12.40 μg/L。土壤中多环芳烃分析的加标回收率为82.4%~110.6%, RSD为2.6%~7.9%(n=3)。与美国国家环境保护局检测土壤中多环芳烃的方法比较,结果一致,准确性高。实验表明,该方法萃取效率高,灵敏可靠,操作简便,重现性好,可满足土壤等样品中痕量多环芳烃检测的要求。     

Ionic liquid-mediated sol–gel coatings for capillary microextraction

Ionic liquid (IL)-mediated sol–gel hybrid organic–inorganic materials present enormous potential for effective use in analytical microextraction. This opportunity, however, has not yet been explored. One obstacle to materializing this prospect arises from high viscosity of ILs significantly slowing down sol–gel reactions. In this work, we developed a method that overcomes this hurdle and provides IL-mediated advanced sol–gel materials for capillary microextraction (CME). We examined two different ILs: (a) a phosphonium-based IL, trihexyltetradecylphosphonium tetrafluoroborate, and (b) a pyridinium-based ionic liquid, N-butyl-4-methylpyridinium tetrafluoroborate. These ILs were evaluated in conjunction with two types of hydroxy-terminated polymers: (a) two Si–OH terminated polymers (PDMS and BMPO), and (b) two C–OH terminated polymers (PEG and polyTHF) that differ in their sol–gel reactivity. Scanning electron microscopy results demonstrate that ILs can serve as porogenic agents in sol–gel reactions. The IL-mediated sol–gel coatings prepared with silanol-terminated polymers provided up to 28 times higher extractions in off-line CME-GC compared to analogous sol–gel coatings prepared without any IL in the sol solution. Contrary to this, the IL-mediated sol–gel coatings prepared with C–OH terminated polymers provided lower extraction efficiencies compared to their IL-free counterparts. These observations were explained by (a) lower sol–gel reactivity of C–OH groups in PEG and polyTHF compared to Si–OH groups in PDMS and in hydrolyzed alkoxysilane precursors and (b) extremely high viscosity of ionic liquids. This study shows that IL-generated porous morphology alone is not enough to provide effective extraction media: careful choice of the organic polymer and the precursor with close sol–gel reactivity must be made to ensure effective chemical bonding of the organic polymer to the created sol–gel material to be able to provide the desired sorbent characteristics. Additionally, IL-mediated sol–gel PDMS coatings provided run-to-run RSD values of 4.2–5.0% and detection limits ranging from 3.2 ng/L to 17.4 ng/L. PDMS sol–gels prepared without ILs provided RSD values of 2.8–14.1%, and detection limits ranging from 4.9 ng/L to 487.0 ng/L.     

整体柱在线固相微萃取-高效液相色谱同步富集检测水中的苯氧羧酸类除草剂

采用C18毛细管整体柱作为固相微萃取整体柱,构建在线固相微萃取-高效液相色谱联用系统,同步富集检测环境水样中的5种苯氧羧酸类除草剂。详细考察了联用系统运行条件对富集检测的影响。联用系统运行最佳参数为:固相微萃取整体柱长度20 cm,进样流速0.04 mL/min,进样13 min,洗脱流速0.02 mL/min,洗脱5 min。在最佳条件下,5种苯氧羧酸类除草剂的检出限为:9 μg/L (苯氧丙酸)、4 μg/L (2-(2-氯)-苯氧丙酸)、4 μg/L (2-(3-氯)-苯氧丙酸)、5 μg/L (2,4-二氯苯氧乙酸)、5 μg/L (2-(2,4-二氯苯氧基)丙酸)。与HPLC系统直接进样对比,联用系统对5种检测对象表现出优良的富集能力。5种苯氧羧酸类除草剂的回收率在79.0%~98.0%之间(RSD≤3.9%)。该方法成功应用于水样中5种苯氧羧酸类除草剂的检测,结果令人满意。     

整体柱在线固相微萃取-高效液相色谱法分析爽肤水中痕量雌激素

以甲基丙烯酸缩水甘油酯(GMA)为功能单体、乙二醇二甲基丙烯酸酯(EDMA)为交联剂,偶氮二异丁腈(AIBN)为引发剂、甲醇及正己烷(14∶5,v/v)为二元致孔剂,通过原位聚合反应制备了聚甲基丙烯酸缩水甘油酯(Poly(GMA-co-EDMA))毛细管整体柱。研究表明,制备的Poly(GMA-co-EDMA)整体柱具有良好的通透性和较低的柱压(1.5×106Pa,冲洗流速0.5 mL/min)。该整体柱对雌二醇、炔雌醇、雌酮和己烯雌酚的富集倍数分别为86、116、77和86。构建了整体柱在线微萃取接口装置,建立了整体柱在线固相微萃取-高效液相色谱(HPLC)测定爽肤水中痕量雌二醇、炔雌醇、雌酮和己烯雌酚的分析方法。该分析方法的检出限(S/N=3)为0.05~0.20μg/L。将方法应用于爽肤水中雌激素的检测,加标回收率为69.3%~111.3%,RSD5.0%。所建立的方法简单、快速、灵敏、准确,可满足爽肤水中痕量雌激素的分析。     

Ultra-high-stability,pH-resistant sol–gel titania poly(tetrahydrofuran) coating for capillary microextraction on-line coupled to high-performance liquid chromatography

A sol–gel titania poly(tetrahydrofuran) (poly-THF) coating was developed for capillary microextraction hyphenated on-line with high-performance liquid chromatography (HPLC). Poly-THF was covalently bonded to the sol–gel titania network which, in turn, became chemically anchored to the inner surface of a 0.25 mm I.D. fused silica capillary. For sample preconcentration, a 38-cm segment of the sol–gel titania poly-THF coated capillary was installed on an HPLC injection port as a sampling loop. Aqueous samples containing a variety of analytes were passed through the capillary and, during this process, the analytes were extracted by the sol–gel titania poly-THF coating on the inner surface of the capillary. Using isocratic and gradient elution with acetonitrile/water mobile phases, the extracted analytes were desorbed into the on-line coupled HPLC column for separation and UV detection. The sol–gel titania poly-THF coating was especially efficient in extracting polar analytes, such as underivatized phenols, alcohols, amines, and aromatic carboxylic acids. In addition, this coating was capable of extracting moderately polar and nonpolar analytes, such as ketones and polycyclic aromatic hydrocarbons. The sol–gel titania poly-THF coated capillary was also able to extract polypeptides at pH values near their respective isoelectric points. Extraction of these compounds can be important for environmental and biomedical applications. The observed extraction behavior can be attributed to the polar and nonpolar moieties in the poly-THF structure. This coating was found to be stable under extremely low and high pH conditions—even after 18 h of exposure to 1 M HCl (pH ≈0.0) and 1 M NaOH (pH ≈14.0).     

Sol–gel coatings with covalently attached methyl,octyl, and octadecyl ligands for capillary microextraction. Effects of alkyl chain length and sol–gel precursor concentration on extraction behavior

Fused silica capillaries with surface-bonded sol–gel coatings containing covalently attached octadecyl, octyl, and methyl groups were prepared for capillary microextraction (CME) hyphenated on-line with high-performance liquid chromatography (HPLC). For this, octadecyltrimethoxysilane (C₁₈TMS), octyltrimethoxysilane (C₈TMS), or methyltrimethoxysilane (MTMS) was used as the respective sol–gel precursor. Hydrolytic polycondensation of these precursors led to the formation of surface-bonded sol–gel sorbents with pendant alkyl groups ready to serve as the extraction medium; no additional surface derivatization reactions were needed to anchor these ligands to the surface. Extraction behaviors of two sets of microextraction capillaries with alkyl-bonded sol–gel coatings were investigated: (a) capillaries prepared with a constant molar concentration of these precursors in the sol solution, and (b) capillaries prepared with varied molar concentrations of C₈TMS in the sol solution. Among the capillaries prepared using sol solutions with the same molar concentration of sol–gel precursor, the detection limits for nonpolar and polar analytes ranged from 0.3 ng/L to 213.9 ng/L. The sol–gel octadecyl-coated capillaries were found to be the most efficient at extracting these analytes, followed by the sol–gel octyl-coated capillaries, followed by the sol–gel methyl-coated capillaries. The results of this study point to the possibility that polar analytes are extracted through synergistic molecular level interactions of the polar and nonpolar parts of the analyte molecules with the alkyl chains and silanol groups within the sol–gel coatings. These coatings also demonstrated run-to-run and capillary-to-capillary reproducibility, with HPLC peak area RSD values ranging from 1.1% to 9.6% and 1.3% to 10.0%, respectively. In the set of sol–gel octyl capillaries with varied molar concentrations, the capillaries prepared with 0.514 M concentration of C₈TMS in the sol solution were most efficient in extracting nonpolar and polar analytes. When higher or lower concentrations of C₈TMS were used in the sol solution, the resulting sol–gel coated capillaries were less efficient in extracting nonpolar and polar analytes.     

High-temperature solvent stability of sol–gel germania triblock polymer coatings in capillary microextraction on-line coupled to high-performance liquid chromatography

Germania-based sol–gel organic–inorganic hybrid coatings were prepared for on-line coupling of capillary microextraction with high-performance liquid chromatography. For this, a germania-based sol–gel precursor, tetra-n-butoxygermane and a hydroxy-terminated triblock copolymer, poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) were used. These sol–gel germania triblock polymer coatings were chemically anchored to the inner walls of a fused silica capillary (0.25 mm I.D.) in course of its evolution from the sol solution. Scanning electron microscopy images of the sol–gel germania triblock polymer coating were obtained to estimate the coating thickness. For the first time, the analyte distribution constants between a sol–gel germania organic–inorganic hybrid coating and the samples (K_cs) were determined. For a variety of analytes from different chemical classes, including polycyclic aromatic hydrocarbons (PAHs), ketones, alcohols, phenols and amines, the K_cs values ranged from 8.1 × 10¹ to 5.6 × 10⁴. Also, for the first time, the stability of the sol–gel germania-based coating in high-temperature reversed-phase solvent environment was evaluated. The sol–gel germania triblock polymer coatings were capable of surviving exposure to high-temperature solvent conditions (200 °C) with little change in extraction capabilities. This demonstrates that sol–gel germania triblock polymer hybrid materials might be suitable for further applications in high-temperature HPLC. The reproducibility of the method for preparation of the sol–gel germania triblock polymer coatings was also evaluated, and the capillary-to-capillary RSD values ranged from 5.3 to 6.5%. The use of higher flow rates in extraction was found to significantly reduce the time required (from 30–40 to 10–15 min) to reach equilibrium between the sol–gel germania triblock polymer coating and the analytes in the sample solution.     

Liquid phase microextraction applications in food analysis

Over the last years, liquid-phase microextraction (LPME) in its different application modes (single drop microextraction, dispersive liquid-liquid microextraction and hollow fiber-LPME) has been increasingly applied for the extraction of both inorganic and organic analytes from different matrices. Its advantages over conventional extraction procedures (simplicity, effectiveness, rapidity and low consumption of organic solvents) has also attracted its application in the complex food analysis field, in which it has clearly provided good and challenging results. A comprehensive review dealing with those articles published since its introduction till the end of March 2011 is presented, offering also a critical vision of the analytical potential of LPME for the analysis of foods.     

An overview of sample preparation and extraction of synthetic pyrethroids from water,sediment and soil

The latest developments in sample preparation and extraction of synthetic pyrethroids from environmental matrices viz., water, sediment and soil were reviewed. Though the synthetic pyrethroids were launched in 1970s, to the best of authors’ knowledge there was no review on this subject until date. The present status and recent advances made during the last 10 years in sample preparation including conservation and extraction techniques used in determination of synthetic pyrethroids in water, sediment and soil were discussed. Pre- and post-extraction treatments, sample stability during extraction and its influence upon the whole process of analytical determination were covered. Relative merits and demerits including the green aspects of extraction were evaluated. The current trends and future prospects were also addressed.