A highly selective solid phase extraction sorbent for pre-concentration of sameridine made by molecular imprinting

Summary A novel approach to solid phase extraction, based on the use of a highly selective molecularly imprinted polymer, is presented. The versatility of this type of sorbent for solid phase extraction was demonstrated in a model batch-wise pre-concentration of sameridine prior to gas chromatography. Problems associated with leakage of remaining imprint molecules during the desorption phase could be eliminated by the use of a close structural analogue of sameridine as the imprint species. It was found that a major benefit of the imprinted polymer was its specificity, which lead to distinctly cleaner chromatographic traces and ability to improve sensitivity by extracting sameridine from larger sample volumes.     

Indirect determination of organic compounds by atomic-absorption spectrophotometry

A review of the published methods for analysis of organic compounds by atomic-absorption spectrophotometry is given. Most of the applications are based on precipitation of metal compounds or solvent extraction of metal chelates or ion-association complexes. Although many of the methods offer great sensitivity, simplicity, and speed of analysis, few have been widely accepted by analysts, but some have proved to be satisfactory in field trials.     

Electrospun nanofibers as sorbent material for solid phase extraction

Electrospinning has emerged as the most versatile technique for nanofiber fabrication. Owing to their large surface area to volume ratio, electrospun nanofibers have the potential to serve as a good sorbent material for solid phase extraction (SPE) based techniques. The ability to incorporate a variety of functionalities prior or post-electrospinning presents a platform to tune the sorbents for specific applications. It is the aim of this contribution to highlight some of the recent developments that harness the great potential of electrospun nanofibers as sorbents for SPE. The review discusses the various ways in which the electrospinning technique addresses two important parameters for sorbent material, which are sorptive capacity and selectivity. It concludes by presenting and discussing the potential for development of SPE format technology and configurations based on electrospun nanofibers.     

Evaluation of the possibility of detecting benzenic pollutants by direct spectrophotometry on PDMS solid sorbent

Solid-phase extraction has become one of the most commonly used techniques for preconcentration of analytes from environmental samples. In the standard use of solid sorbent phases the extracted pollutants are subsequently eluted with a suitable organic solvent before chromatographic analysis. An alternative to this procedure is analysis of the adsorbed and concentrated pollutants by direct application of a spectroscopic method (fluorimetry or absorptiometry) to the phase. Although this method cannot be expected to give results as precise as those given by chromatographic methods, it might have valuable applications, particularly for "on site" pollution monitoring. This paper reports an evaluation of the capability of the method for the spectrophotometric detection of BTX (benzene, toluene, xylenes) in aqueous media and in contaminated atmospheres, with polydimethylsiloxane (PDMS) as sorbent. The tests performed, with the estimated detection limits, indicate that the method is relatively simple and easy to operate and sensitive enough for application to the monitoring of pollution both in water and in air in an industrial ambient atmosphere.     

新试剂NSPAR固相萃取光度法测定氰化渣中铂的研究

在pH2.5的氯乙酸NaOH缓冲介质中,吐温80存在下,磺硝酚偶氮若丹宁(NSPAR)与铂反应生成2∶1稳定络合物,该络合物可被WatersSep PakC18小柱固相萃取,用氮氮二甲基甲酰氨(DMF)洗脱后用光度法测定。在洗脱液介质中,λmax=535nm,摩尔吸光系数ε=6.33×104L·mol-1·cm-1。铂质量浓度在0 001～0 080μg/mL内符合比尔定律,本方法可用于氰化渣中铂的测定。     

钯与对若丹宁偶氮苯甲酸络合物的固相萃取和光度测定

根据新试剂对若丹宁偶氮苯甲酸(RABA)与钯的显色反应及C18固相萃取小柱对显色络合物的固相萃取,建立了一种测定痕量钯的新方法,在pH为2.0～4.0的HCl-邻苯二甲酸氢钾(HCl-KHP)缓冲介质中,在CTMAB存在下,钯与RABA发生反应形成1:1的稳定络合物,该络合物可用C18固相萃取小柱富集,小柱上富集的络合物用乙醇洗脱后用光度法测定,在富集后的测定液中,络合物最大吸收波长为500 nm,摩尔吸光系数ε=1.36×105 L·mol-1·cm-1,Pd2 量在0.1～1.0 μg/mL内符合比尔定律,方法用于催化剂中钯的测定.     

Reversed phase StrataTM-X resin as sorbent for automatic on-line solid phase extraction atomic absorption spectrometric determination of trace metals: comparison of polymeric-based sorbent materials

A novel on-line flow injection solid phase extraction method for the preconcentration of trace toxic metals prior determination by flame atomic absorption spectrometry (FI-SPE-FAAS) was developed. The potential application of the hydrophobic reversed phase co-polymer sorbent Strata^TM-X packed into an on-line microcolumn for the quantification of Cd(II), Pb(II), Cu(II) and Cr(VI) was demonstrated for the first time. The method was based on the on-line formation of metal complexes using sodium diethyl-dithiocarbamate (DDTC) and on the subsequent retention of them onto the sorbent material. The target analytes were completely eluted by methanol and, subsequently, directed to FAAS for quantification. All chemical and flow variables affecting the performance of the developed method were thoroughly studied and optimised. For a preconcentration time of 90 s and a sampling frequency of 28 h^?1, enhancement factors of 72, 140, 185, 63 and detection limits of 0.18, 1.6, 0.20 and 1.2 μg L ^?1 were obtained for Cd(II), Pb(II), Cu(II) and Cr(VI), respectively. The accuracy of the FI-SPE-FAAS method was evaluated by analysing certified reference materials as well as spiked environmental water samples. Furthermore, a comparative study of the analytical characteristics, the properties as well as the chemical structures of commercial polymeric based sorbent materials was employed. Strata-X sorbent was compared against Hypersep^TM SCX, Bond Elut® Plexa^TM PCX, Oasis-HLB^TM and Nobias^TM PA-1, regarding the adaptation in on-line FI-SPE-FAAS systems for metal determination, and herein presented.     

水中挥发酚的在线蒸馏-固相萃取分离富集及测定

在顺序注射系统中实现了挥发酚的快速自动在线蒸馏,并用AmberliteXAD-7树脂微填充柱对其与4-氨基安替比林的衍生物在线固相萃取,被富集的衍生物可用少量乙醇有效地洗脱回收,以分光光度法检测.方法可用于较高浓度挥发酚(mg/L)样品的测定,也可根据需要适当增大进样体积,经富集后实现更低浓度水平(μg/L)挥发酚的测定.当富集过程中进样体积为4mL时,方法测定挥发酚的线性范围为0.004~0.3mg/L,检出限为0.002mg/L,相对标准偏差为1.4%(0.1mg/L,n=9).对多种实际水样中的挥发酚进行了测定,加标回收实验的回收率在96%~102%之间.     

Environmental analysis of organic compounds in water using solid phase micro extraction

Solid Phase Micro Extraction (SPME) involves exposing a fused silica fiber coated with stationary phase to a contaminated water sample. The organic analytes become partitioned between the stationary phase and the water and when equilibrium is reached the fiber is removed from the solution and the analytes are thermally desorbed in the injector of a gas chromatograph. The fiber is contained in a syringe to facilitate handling. Factors which affect linear range, limit of detection, and total analysis time are discussed with regard to the development of a method for analysis of volatile compounds in environmental water samples. The sensitivity of the method was determined by the thickness of the film of stationary phase; the equilibration time, however, increased with the film thickness, although it can be minimized by use of a cross-shaped stirrer bar. Increasing the thickness of stationary phase in the analytical column enables the cryofocusing temperature to be increased from ?40 to ?15°C. With an ion trap mass spectrometer, detection limits required by the US Environmental Protection Agency are met for all compounds except chloromethane and chloroethane. The method has been applied to environmental water samples.     

固相萃取膜技术用于自来水中丙烯酰胺的测定

开发了一种简便快速的固相萃取膜(SPE disk)技术,实现了对500 mL自来水中微量丙烯酰胺的富集,采用高效液相色谱法(HPLC)完成其定性和定量测定。比较不同填料的吸附情况,选择活性炭作为丙烯酰胺的最佳吸附剂。考察了洗脱剂种类、洗脱剂体积、洗脱速率和穿透体积等条件对萃取结果的影响,优化了色谱分离条件。经膜萃取过的丙烯酰胺在0.05～0.5 mg/L质量浓度范围内,其峰面积与质量浓度的线性关系良好,相关系数为0.998,检出限为20 ng/L。该方法对不同体积、不同浓度的丙烯酰胺溶液的回收率为94.12%～100.2%,相对标准偏差为2.09%～4.51%(n=3),自来水样品的加标回收率为79.96%。该方法操作简单、快速、灵敏度高,适合对水样中丙烯酰胺的测定。     

A novel porous carbon and its perspectives for the solid phase extraction of volatile organic compounds

A porous carbon sorbent prepared by controlled pyrolysis of saccharose in a matrix of silica gel was tested for the preconcentration of a variety of compounds differing in polarity and volatility (hydrocarbons, halocarbons, oxygenated compounds) in simulated and real air samples. The trapped components were desorbed off-line by liquid-(carbon disulphide and carbon disulphide with 1% methanol) and on-line by thermo-desorption in combination with HRCGC. Adsorption-desorption properties of the sorbent were evaluated according to the determined recovery values, whereby physicochemical interactions of both the sorbent and solute were taken into consideration. With oxygenated compounds recovery data indicate the presence of active sites on the surface of the sorbent.Dedicated to Professor Dr. Dr. h.c. mult. J. F. K. Huber on the occasion of his 70th birthday     

槲皮素分子印迹聚合物的制备及固相萃取性能研究

采用分子印迹技术, 以槲皮素为模板分子, 丙烯酰胺为功能单体, 乙二醇二甲基丙烯酸脂为交联剂, 通过热引发聚合, 制备了槲皮素分子印迹聚合物, 并通过装入固相萃取柱试验了聚合物对槲皮素的选择性能. 结果表明, 该分子印迹聚合物对槲皮素具有高度选择性, 为从天然产物中高效分离富集黄酮活性成分槲皮素提供了一种新材料.     

Application of a new nanoporous sorbent for extraction and pre-concentration of lead and copper ions

The authors describe a method for the trace determination of copper (II) and lead (II) in water and fish samples using solid-phase extraction via siliceous mesocellular foam functionalised by dithizone. Siliceous mesocellular was functionalised with dithizone, and the resulting sorbent was characterised by scanning electron microscopy, surface area analysis, thermogravimetric/differential thermal analysis and FTIR. Following solid-phase extraction of target ions by the sorbent, copper and lead ions were quantified by flame atomic absorption spectrometry. Factors affecting the sorption and desorption of target ions by the sorbent were evaluated and optimised. The calibration plot is linear in the 1 – 500 μg L^?1 copper (II) and 3–700 μg L^?1 lead (II) concentration range. The relative recovery efficiency in real sample analysis is in the range from 96 to 102%, and precision varies between 1.7 and 2.8%. It is should be noted that the limits of detection for the copper and lead analysis were 0.8 and 1.6 μg L^?1, respectively. Also, the adsorption capacities for copper and lead ions were 120 and 160 mg g^?1, respectively. The obtained pre-concentration factor for the lead and copper ions by the proposed solid-phase extraction was 75. The method was successfully applied to the determination of low levels of copper (II) and lead (II) in tap, Caspian sea, Persian gulf and lake water and also their detection in fish samples.     

Combination of solid phase extraction and in vial solid phase derivatization using a strong anion exchange disk for the determination of nerve agent markers

Alkylphosphonic acids (APAs) are degradation products and chemical markers of organophosphorous (OP) nerve agents (chemical warfare agents). Anion exchange disk-based solid phase extraction (SPE) has been combined with in vial solid phase derivatization (SPD) and GC–MS analysis for the determination of APAs in aqueous samples. The optimization of critical method parameters, such as the SPD reaction, was achieved using statistical experimental design and multivariate data analysis. The optimized method achieved quantitative recoveries in the range from 83% to 101% (n = 13, RSD from 4% to 10%). The method was sensitive, with LODs in SIM mode of 0.14 ppb, and demonstrated excellent linearity with an average R² ≥ 0.99 over the concentration range of 0.07–1.4 ppm in full scan mode and from 0.14 ppb to 14 ppb in SIM mode. For forensic applications, aqueous samples containing APAs at concentrations exceeding 14 ppb were concentrated and target analytes were successfully identified by spectral library and retention index matching. Method robustness was evaluated using aqueous samples from the official OPCW Proficiency Test (round 19) and all APAs present in the sample were conclusively identified. The SPE disk retained the underivatized APAs in a stable condition for extended periods of time. No significant losses of APAs from the disk were observed over a 36-day period. Overall, the method is well suited to the qualitative and quantitative analysis of degradation markers of OP nerve agents in aqueous matrices with simplicity, a low risk of cross-contamination and trace level sensitivity.     

Liquid-liquid extraction of osmium thiocyanate with hexamethylphosphoramide and direct spectrophotometric determination in the organic phase

The use of hexamethylphosphoramide (HMPA) in the osmium-thiocyanate system makes the method more sensitive and selective. The blue colour formed by osmium(VIII) with thiocyanate in 1.5M hydrochloric acid is intensified in the presence of HMPA and the complex becomes readily extractable into chloroform. The colour system has its absorption maximum at 595 nm and obeys Beer's law over the range 0.5-16 mug of Os per ml. The optimum range is 2-10 mug/ml. The molar absorptivity is 2.09 x 10(4)l.mole(-1).cm(-1). The method is simple, sensitive and free from interference from many metal ions, including ruthenium and other platinum metals.     

Estimating uncertainty in matrix solid phase extraction methodology for the determination of chlorinated compounds in fish

In this study, a detailed process of uncertainty estimation associated with matrix solid phase dispersion method (MSPD) for the extraction of organochlorinated compounds from fish coupled with gas chromatography is given. The evaluation of uncertainty arising from trueness using fully nested experimental designs is presented by estimating proportional bias, in terms of recovery. The uncertainty of measurements associated with the actual chromatographic process was also estimated. The methodology was applied for the determination of selected organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in real fish samples, from selected study locations in Western Greece (Mesologgi lagoon and Trichonida lake), based on chromatographic techniques. The sources of uncertainty are presented along with the calculated combined uncertainty terms derived from the analytical procedure and chromatographic process. The estimation of uncertainty was included in the presentation of final determinations.     

Headspace solid phase micro extraction GC-ECD determination of volatile organic chlorinated hydrocarbons in soils

Soil samples were suspended in a suitable aqueous solvent and a solid phase microextraction (SPME) fibre was used to sample the headspace (HS) for five volatile chlorinated compounds (VOX). Their determination was made by GC-ECD technique in the splitless mode. Preliminary studies on the effects of methanol and of the sand/clay ratio on the fibre extraction were made. Four experimental factors, namely, extraction time, extraction temperature, pH and NaCl%, able to affect distribution of the analytes among the four different phases, were varied in suitable ranges. A multivariate approach applied to the face centred cube (FCC) experimental design, was used to try to optimise the overall sample response. The suitable set of factors found for the determination of chloroform, 1,2-dichloroethane, trichloroethylene, 1,1 ,2-trichloroethane, 1,1,2,2-tetrachloroethane, was a compromise among the relevant optimal factor sets of the single analytes. Detection limits of 0.003 ng, 0.022 ng, 0.001 ng, 0.015 ng and 0.002 ng were found respectively for the five cited analytes. The method was successfully used to determine the analyte contents in two real soils sampled in an industrial area.     

固相萃取光度法测定烟草中的挥发酚

研究了用Waters Sep-Park-C18固相萃取小柱萃取测定烟草样品中的挥发酚的方法。用自动水蒸汽蒸馏仪蒸馏出烟草样品中的挥发酚，4-氨基安替比林显色，显色产物可用Waters Sep-Park-C18固相萃取小柱萃取，以乙醇洗脱后用分光光度法测定，该方法可用于烟草样品中挥发酚的测定。