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Analytica Chimica Acta (v.736, #)

Editorial Board (pp. iii).

Nanoengineered micro gold shells for LDI-TOF analysis of small molecules by Jeongwook Lee; Juhee Lee; Taek Dong Chung; Woon-Seok Yeo (pp. 1-6).
Display Omitted► Micro gold shells with embossed nanostructures were used for desorption/ionization of analytes. ► This micro gold shell gave the clear MS spectra without any background interference. ► It afforded the better sensitivity and higher signal-to-noise ratio compared to AuNPs.This paper reports on analyses of small molecules with laser desorption/ionization time of flight (LDI-TOF) mass spectrometry (MS) using nanostructure-embedded micro gold shells (μAuSs). The mass analyses of amino acids, sugars, peptides, and their mixtures gave apparent mass peaks for analytes without any significant background interferences. μAuSs afforded a better limit of detection (LOD) and a higher signal-to-noise ratio than gold nanoparticles, which are commonly used for LDI-TOF analysis of small molecules. We believe μAuSs have advantages in terms of simplicity, detection limit, and reproducibility, and therefore, they constitute a significant addition to the organic matrix-free analytical tools that are currently in wide use.

Keywords: LDI-TOF; Matrix-free; Micro gold shell; SALDI; Small molecule analysis


Overview of extraction, clean-up and detection techniques for the determination of organic pollutants in sewage sludge: A review by O. Zuloaga; P. Navarro; E. Bizkarguenaga; A. Iparraguirre; A. Vallejo; M. Olivares; A. Prieto (pp. 7-29).
Display Omitted► A peer-review literature on the analysis of organics in sludge is presented. ► Both priority and emerging pollutants were detected in sludge samples. ► Current state-of-the-art is discussed involving extraction, clean-up and analysis. ► Classical techniques represent high percentages of the papers of organics in sludge. ► PLE represents more than a half of the total manuscripts using novel techniques.Priority pollutants constitute only a part of the large chemical pollution puzzle where the number of potentially hazardous chemicals that reaches the environment is very wide and new substances are constantly being developed and released. Among them, a diverse group of unregulated pollutants, many times called “emerging” contaminants, including pharmaceuticals and personal care products (PPCPs), is found. This group of emerging contaminants constitutes a broad class of chemicals widely used in daily life, such as synthetic fragrances, UV filters, antiseptics, antioxidants and insect repellents. The large amount of them and other emerging contaminants consumed in modern society contribute as well to a wide range of contamination in the aquatic environment, introduced mainly through wastewater treatment plants (WWTPs). The agricultural application of sewage sludge has become the most widespread method for its disposal, since it is the most economical outlet for sludge and offers the opportunity to recycle plant nutrients and organic matter to soil for crop production. However, due to the presence of metals, organic contaminants and pathogenic bacteria in sewage sludge, concern has increased about the human exposure to priority and emerging pollutants via crops cultivated in sewage/compost-amended soils. Because of the potentially dangerous consequences of the presence of those contaminants in the environment, data concerning the concentration, fate and behavior of those pollutants is urgently necessary. With this purpose in mind, sensitive and robust analytical methods for complex matrices such as sewage sludge are necessary in order to obtain reliable data that help us to understand the risk of agricultural use of sewage sludge. The present manuscript reviews the different approaches present in the literature for determining organic pollutants (priority and emerging) in sewage sludge. A review of the last ten years has been performed and the three main steps of an analytical procedure (extraction, clean-up and analysis) have been reviewed.

Keywords: Sewage sludge; Priority and emerging organic pollutants; Extraction techniques; Clean-up protocols; Instrumental analysis


Determination of oil reservoir radiotracer (S14CN−) in a single step using a plastic scintillator extractive resin by H. Bagán; A. Tarancón; L. Stavsetra; G. Rauret; J.F. García (pp. 30-35).
.Display Omitted► A new procedure for S14CN− radiotracer determination using PS resin was established. ► The minimum detectable activity for a 100mL sample is 0.08BqL−1. ► The minimum quantifiable activity for a 100mL sample is 0.31BqL−1. ► PS resin is capable to quantify S14CN− radiotracer samples with errors lower than 5%. ► PS resin is also capable to quantify complex matrices obtained from oil reservoirs.The analysis of radiotracers is important in the study of oil reservoir dynamics. One of the most widely used radiotracer is S14CN−. Prior to activity measurements by Liquid Scintillation (LS), routine determinations require the pretreatment steps of purification and concentration of the samples using anion exchange columns. The final elution media produces samples with high salt concentration that may lead to problems with phase separation during the LS measurement. Plastic Scintillation (PS) is an alternative technique that provides a solid surface that can be used as a platform for the immobilisation of selective extractants to obtain a PS resin. The proposed procedure unifies chemical separation and sample measurement preparation in a single step, serving to reduce the number of reagents needed and manpower required for the analysis while also avoiding mixed waste production by LS.The objective of this study is to develop a PS resin for the determination of14C-labelled thiocyanate radiotracer in water samples.For this purpose, the immobilisation procedure was optimised, including optimisation of the proportion of PS microspheres:extractant and the use of a control blank to monitor the PS resin immobilisation process. The breakthrough volume was studied and the detection and quantification limits for 100mL of sample were determined to be 0.08BqL−1 and 0.31BqL−1, respectively. The established procedure was applied to active samples from oil reservoirs and errors lower than 5% in the sample determinations were obtained.

Keywords: Plastic scintillation; Liquid scintillation; S; 14; CN; −; Radiotracers; Oil reservoirs; Radiocarbon


Principal component and Tucker3 analyses of high performance liquid chromatography with diode-array detection fingerprints of crude extracts of Erythrina speciosa Andrews leaves by Patricia Kaori Soares; Roy Edward Bruns; Ieda Spacino Scarminio (pp. 36-44).
Display Omitted► Simultaneous chromatographic, spectroscopic and mixture proportion correlations. ► Tucker3 analysis of chromatographic, spectral and solvent mixture proportions. ► HPLC-DAD spectral characterization of chromatographic peaks.Mixtures of ethanol, dichloromethane, hexane and acetone obtained according to a statistical design have been used to extract substances from Erythrina speciosa Andrew leaves for chromatographic fingerprinting. The plant extracts from each mixture were analyzed by HPLC-DAD providing UV–vis spectra for each chromatographic peak. These chromatograms and spectra for the design mixtures were then treated with principal component (PCA), Tucker3 and PARAFAC analyses. PCA indicated the existence of five different chromatographic fingerprints for the leave extracts depending on the solvent mixture composition. Different chromatographic peak areas were strongly correlated with the mixture proportions of acetone, dichloromethane and ethanol. Tucker3 and PARAFAC analyses were very useful for identifying simultaneous correlations between chromatographic peak areas, spectral band absorbances and solvent proportions. The acetone proportion was highly correlated with the area of the 3.69min retention time peak and the spectral absorbances between 250 and 260nm, consistent with the presence of natural polyphenols. The dichloromethane mixture proportion was strongly correlated with the 12.19min chromatographic peak area and a single spectral absorbance at 201nm. This spectral absorption is characteristic of the electronic structures of terpenes and alkaloids.

Keywords: Extraction optimization; Simplex centroid design; Tucker3; Principal components; Erythrina speciosa; Andrews leaves


Iron organic speciation determination in rainwater using cathodic stripping voltammetry by Marie Cheize; Géraldine Sarthou; Peter L. Croot; Eva Bucciarelli; Anne-Claire Baudoux; Alex R. Baker (pp. 45-54).
Display Omitted► A sensitive CLE-ACSV method developed to measure iron organic speciation in rainwater. ► Detection limit for labile Fe is 10–70 times lower than other methods. ► Adequate detection window was defined to detect Fe-complexing natural ligands in rainwater. ► Organic Fe-complexing ligand concentrations were measured for the first time in natural rainwater samples. ► Conditional stability constant of Fe natural organic complexes determined in rainwater.A sensitive method using Competitive Ligand Exchange-Adsorptive Cathodic Stripping Voltammetry (CLE-ACSV) has been developed to determine for the first time iron (Fe) organic speciation in rainwater over the typical natural range of pH. We have adapted techniques previously developed in other natural waters to rainwater samples, using the competing ligand 1-nitroso-2-naphthol (NN). The blank was equal to 0.17±0.05nM ( n=14) and the detection limit (DL) for labile Fe was 0.15nM which is 10–70 times lower than that of previously published methods. The conditional stability constant for NN under rainwater conditions was calibrated over the pH range 5.52–6.20 through competition with ethylenediaminetetraacetic acid (EDTA). The calculated value of the logarithm ofβ′Fe3+(NN)3 increased linearly with increasing pH according tologβ′Fe3+(NN)3=2.4±0.6×pH+11.9±3.5 (salinity=2.9, T=20°C). The validation of the method was carried out using desferrioxamine mesylate B (DFOB) as a natural model ligand for Fe. Adequate detection windows were defined to detect this class of ligands in rainwater with 40μM of NN from pH 5.52 to 6.20. The concentration of Fe-complexing natural ligands was determined for the first time in three unfiltered and one filtered rainwater samples. Organic Fe-complexing ligand concentrations varied from 104.2±4.1nM equivalent of Fe(III) to 336.2±19.0nM equivalent of Fe(III) and the logarithm of the conditional stability constants, with respect to Fe3+, varied from 21.1±0.2 to 22.8±0.3. This method will provide important data for improving our understanding of the role of wet deposition in the biogeochemical cycling of iron.

Keywords: Abbreviations; ARW; artificial rainwater; BPA; N-benzoyl-N-phenylhydroxylamine; chromotropic acid; 4,5-dihydroxynaphtalene-2,7 disulfonic acid; CLE-ACSV; Competitive Ligand Exchange-Adsorptive Cathodic Stripping Voltammetry; DFOB; desferrioxamine mesylate B; DHN; 2,3-dihydroxynaphtalene; EDTA; ethylenediaminetetraacetic acid; E; p; reduction potential of the Fe; III; (NN); 3; complex; EPPS; 3-[4-(2-hydroxyethyl)-1-piperazinyl]propanesulfonic acid; GPES; General Purpose Electrochemical System; HEPES; 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; K; ′; F e; ′; ⁡; DFOB; conditional stability constant with respect to Fe′ for the DFOB complexes; K; ′; Fe; 3; +; DFOB; conditional stability constant with respect to free Fe; 3+; for the DFOB complexes; K; ′; Fe; 3; +; L; conditional stability constant with respect to free Fe; 3+; for the Fe natural organic complexes; K; ′; FeEDTA; the stability constant of the complex Fe-EDTA; K; ′; F e; ′; L; conditional stability constant with respect to Fe′ for the Fe natural organic complexes; K; 1; ,; β; 2; ,; β; 3; ,; β; 4; hydrolysis constants for Fe(III); MES; 2-(N-morpholino)ethanesulfonic acid; Milli-Q; 18.2; MΩ Milli-Q; NN; 1-nitroso-2-naphtol; PAN; 1-(2-pyridylazo)-2-naphtol; PAR; 4-(2-pyridilazo)-resorcinol; RW1, RW2 and RW3; rainwater event collected; SA; salicylaldoxime; TAC; 2-(2-thiazolylazo)-ρ-cresol; TAN; 1-(2-thiazolylazo)-2-naphtol; TAR; 4-(2-thiazolylazo)-resorcinol; UVRW; 0.45; μm; UV-irradiated 0.45; μm filtered rainwater; α; ′; the overall side reaction coefficient; α; F; ⁡; e; ′; side reaction coefficient for all inorganic complexation of Fe (Fe′); α; Fe; 3; +; (; NN; ); 3; side reaction coefficient for the complexation of Fe; 3+; with the artificial ligand; α; Fe; 3; +; EDTA; side reaction coefficient for the complex Fe; 3+; EDTA; β; ′; Fe; 3; +; (; NN; ); 3; conditional stability constant with respect to free Fe; 3+; for the complex Fe; 3+; (NN); 3Iron organic speciation; Natural rainwater; Voltammetry; Iron-complexing natural ligand concentrations; Conditional stability constants


Electrochemical sensing chemical oxygen demand based on the catalytic activity of cobalt oxide film by Jinqi Wang; Can Wu; Kangbing Wu; Qin Cheng; Yikai Zhou (pp. 55-61).
Display Omitted► A novel electrochemical sensor was developed for COD using cobalt oxide film. ► It exhibited high sensitivity, rapid response, good simplicity and practicability. ► It was used in numerous water samples, and accuracy was tested by standard method.Cobalt oxide sensing film was in situ prepared on glassy carbon electrode surface via constant potential oxidation. Controlling at 0.8V in NaOH solution, the high-valence cobalt catalytically oxidized the reduced compounds, decreasing its surface amount and current signal. The current decline was used as the response signal of chemical oxygen demand (COD) because COD represents the summation of reduced compounds in water. The surface morphology and electrocatalytic activity of cobalt oxide were readily tuned by variation of deposition potential, time, medium and Co2+ concentration. As confirmed from the atomic force microscopy measurements, the cobalt oxide film, that prepared at 1.3V for 40s in pH 4.6 acetate buffer containing 10mM Co(NO3)2, possesses large surface roughness and numerous three-dimensional structures. Electrochemical tests indicated that the prepared cobalt oxide exhibited high electrocatalytic activity to the reduced compounds, accompanied with strong COD signal enhancement. As a result, a novel electrochemical sensor with high sensitivity, rapid response and operational simplicity was developed for COD. The detection limit was as low as 1.1mgL−1. The analytical application was studied using a large number of lake water samples, and the accuracy was tested by standard method.

Keywords: Chemical oxygen demand (COD); Electrochemical sensor; Cobalt oxide; Electrodeposition; Water pollution


Determination of organophosphorus pesticides in ecological textiles by solid-phase microextraction with a siloxane-modified polyurethane acrylic resin fiber by Xianlei Hu; Mingqiu Zhang; Wenhong Ruan; Fang Zhu; Gangfeng Ouyang (pp. 62-68).
Display Omitted► A PUSA/PETA SPME fiber coating was prepared by photo-cured technology. ► The ratio of two monomers was optimized for better extraction performance. ► The fiber showed very good performance for OPPs analysis in textiles.A novel solid-phase microextraction (SPME) fiber coating was prepared with siloxane-modified polyurethane acrylic resin by photo-cured technology. The ratio of two monomers was investigated to obtain good microphase separation structure and better extraction performance. The self-made fiber was then applied to organophosphorus pesticides (OPPs) analysis and several factors, such as extraction/desorption time, extraction temperature, salinity, and pH, were studied. The optimized conditions were: 15min extraction at 25°C, 5% Na2SO4 content, pH 7.0 and 4min desorption in GC inlet. The self-made fiber coating exhibited better extraction efficiency for OPPs, compared with three commercial fiber coatings. Under the optimized conditions, the detection limits of 11 OPPs were from 0.03μgL−1 to 0.5μgL−1. Good recoveries and repeatabilities were obtained when the method was used to determine OPPs in ecological textile.

Keywords: Solid-phase microextraction (SPME); Siloxane-modified polyurethane acrylic resin; Ecological textile; Organophosphorus


Development of a matrix-assisted laser desorption ionization mass spectrometric method for rapid process-monitoring of phthalocyanine compounds by Yi-Ting Chen; Fu-Shing Wang; Zhendong Li; Liang Li; Yong-Chien Ling (pp. 69-77).
Display Omitted► MALDI TOFMS is developed as a rapid means of monitoring the process of phthalocyanine derivatives. ► All- trans retinoic acid is used as matrix to reduce ion fragmentation and background formation. ► Samples from the reaction process are taken for direct analysis by MALDI TOFMS without any cleanup. ► The method is demonstrated for monitoring the synthesis of brominated Ni- and Cu-phthalocyanine.Phthalocyanines (PCs), an important class of chemicals widely used in many industrial sectors, are macrocyclic compounds possessing a heteroaromatic π-electron system with optical properties influenced by chemical structures and impurities or by-products introduced during the synthesis process. Analytical tools allowing for rapid monitoring of the synthesis processes are of significance for the development of new PCs with improved performance in many application areas. In this work, we report a matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOFMS) method for rapid and convenient monitoring of PC synthesis reactions. For this class of compounds, intact molecular ions could be detected by MALDI using retinoic acid as matrix. It was shown that relative quantification results of two PC compounds could be generated by MALDI MS. This method was applied to monitor the bromination reactions of nickel- and copper-containing PCs. It was demonstrated that, compared to the traditional UV–visible method, the MALDI MS method offers the advantage of higher sensitivity while providing chemical species and relative quantification information on the reactants and products, which are crucial to process monitoring.

Keywords: Mass spectrometry; MALDI; TOFMS; Reaction monitoring; Phthalocyanine


Cobinamide chemistries for photometric cyanide determination. A merging zone liquid core waveguide cyanide analyzer using cyanoaquacobinamide by Jian Ma; Purnendu K. Dasgupta; Felix H. Zelder; Gerry R. Boss (pp. 78-84).
Display Omitted► Complete equilibrium constant data for the cyanide–water–hydroxide-cobinamide (Cbi) system. ► Elucidation: spectral and kinetic behavior of CN− added to OH(H2O)Cbi. ► Best ever reported LOD for cyanide (8nM) with 40 sample h−1 throughput. ► Pattern of salivary CN− and SCN− after cigarette smoking.Diaquacobinamide (H2O)2Cbi2+ or its conjugate base hydroxyaquacobinamide (OH(H2O)Cbi+)) can bind up to two cyanide ions, making dicyanocobinamide. This transition is accompanied by a significant change in color, previously exploited for cyanide determination. The reagent OH(H2O)Cbi+ is used in excess; when trace amounts of cyanide are added, CN(H2O)Cbi+ should be formed. But the spectral absorption of CN(H2O)Cbi+ is virtually the same as that of OH(H2O)Cbi+. It has been inexplicable how trace amounts of cyanide are sensitively measured by this reaction. It is shown here that even with excess OH(H2O)Cbi+, (CN)2Cbi is formed first due to kinetic reasons; this only slowly forms CN(H2O)Cbi+. This understanding implies that CN(H2O)Cbi+ will itself be a better reagent.We describe a single valve merging zone flow analyzer that allows both sample and reagent economy. With a 50cm liquid core waveguide (LCW) flow cell and an inexpensive fiber optic – charge coupled device array spectrometer, a S/N=3 limit of detection of 8nM, a linear dynamic range to 6μM, and excellent precision (RSD 0.49% and 1.07% at 50 and 100nM, respectively, n=5 each) are formed. At 1% carryover, sample throughput is 40h−1. The setup is readily used to measure thiocyanate with different reagents. We demonstrate applicability to real samples by analyzing human saliva samples and hydrolyzed extracts of apple seeds, peach pits, and almonds.

Keywords: Cyanide; Cobinamide; Merging-zone; Liquid core waveguide


Development of a single-chain variable fragment-alkaline phosphatase fusion protein and a sensitive direct competitive chemiluminescent enzyme immunoassay for detection of ractopamine in pork by Jie-Xian Dong; Zhen-Feng Li; Hong-Tao Lei; Yuan-Ming Sun; Frédéric Ducancel; Zhen-Lin Xu; Jean-Claude Boulain; Jin-Yi Yang; Yu-Dong Shen; Hong Wang (pp. 85-91).
Detection model of dc-CLEIA based on anti-RAC scFv-AP fusion protein.Display Omitted► The scFv-AP fusion protein against ractopamine (RAC) was produced. ► A dc-CLEIA for RAC was developed based on the purified scFv-AP fusion protein. ► The sensitivity of dc-CLEIA was 10 times as sensitive as dc-ELISA for RAC. ► Recovery tests from pork samples were studied. ► Good accuracy was obtained.A rapid, sensitive chemiluminescent enzyme immunoassay (CLEIA) for ractopamine (RAC) based on a single-chain variable fragment (scFv)-alkaline phosphatase (AP) fusion protein was developed. The scFv gene was prepared by cloning the heavy- and light-chain variable region genes (VH and VL) from hybridoma cell line AC2, which secretes antibodies against RAC, and assembling VH and VL genes with a linker by means of splicing overlap extension polymerase chain reaction. The resulting scFv gene was inserted into the expression vector pLIP6/GN containing AP to produce the fusion protein in Escherichia coli strain BL21. The purified scFv-AP fusion protein was used to develop a direct competitive CLEIA (dcCLEIA) protocol for detection of RAC. The average concentration required for 50% inhibition of binding and the limit of detection of the assay were 0.25±0.03 and 0.02±0.004ngmL−1, respectively, and the linear response range extended from 0.05 to 1.45ngmL−1. The assay was 10 times as sensitive as the corresponding enzyme-linked immunosorbent assay based on the same fusion protein. Cross-reactivity studies showed that the fusion protein did not cross react with RAC analogs. DcCLEIA was used to analyze RAC spiked pork samples, and the validation was confirmed by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS). The results showed a good correlation between the data of dc-CLEIA and HPLC–MS ( R2>0.99), indicating that the assay was an efficient analytical method for monitoring food safety.

Keywords: Ractopamine; Single-chain variable fragment; Fusion protein; Chemiluminescent enzyme immunoassay; Pork


Part two: Analytical optimisation of a procedure for lead detection in milk by means of bismuth-modified screen-printed electrodes by Josefina Calvo Quintana; Fabiana Arduini; Aziz Amine; Kees van Velzen; Giuseppe Palleschi; Danila Moscone (pp. 92-99).
Display Omitted► Environmentally friendly bismuth-modified screen-printed electrodes were used for lead detection in milk. ► Novel cost-effective milk-treatment procedure was developed using wet digestion with HCl, HClO4 and H2O2 combined with ultrasonic treatment. ► Useful dedicated software able to lead an unskilled operator in each step of the analysis has been developed. ► The analytical method proposed allows the detection of lead in milk at legal limit level.This work reports the optimisation of a new analytical method for lead ion detection in milk; the electrochemical detection scheme is based on the method that was described in Part I . It features the use of a disposable, environmentally friendly bismuth film electrode to replace the traditionally used (toxic) mercury one while here we report an arduous development of sample treatment so that the simple device can be applied as a screening tool in many settings. For this purpose, a milk pre-treatment procedure by means of wet digestion with HCl, HClO4, and H2O2 combined with an ultrasonic treatment was developed. The detection of lead ions in treated milk was then carried out using a disposable screen-printed electrode modified with Nafion® and an “in situ” bismuth film, with the analysis being performed in anodic stripping voltammetry mode. The analytical method developed allows the detection of milk contaminated with lead ions at a concentration of 20μgKg−1 (legal limit) and it can be proposed as a screening method for routine analysis of lead ions in milk with the advantage of employing inexpensive and portable instrumentation. Moreover, dedicated software supported by a portable instrument introduces procedures that are essential to avoid distortion from ambient lead contamination and also makes it possible for an unskilled operator to carry out each step of the analysis.

Keywords: Lead; Bismuth; Milk; Sample pre-treatment; Stripping analysis; Screen-printed electrode


Parts per billion-level detection of benzene using SnO2/graphene nanocomposite composed of sub-6nm SnO2 nanoparticles by Fan-Li Meng; Hui-Hua Li; Ling-Tao Kong; Jin-Yun Liu; Zhen Jin; Wei Li; Yong Jia; Jin-Huai Liu; Xing-Jiu Huang (pp. 100-107).
SnO2/graphene nanocomposite composed of 4–5nm SnO2 nanoparticles was synthesized by one-step wet chemical method and the form mechanism of the nanocomposite is clearly interpreted. The detection limit of the nanocomposite was as low as 5ppb to toxic benzene.Display Omitted► We synthesized SnO2/graphene nanocomposite using a simple one-step wet chemical method. ► The nanocomposite composed of 4–5nm SnO2 nanoparticles. ► Toxic benzene was detected by such kind of nanocomposite. ► The detection limit to toxic benzene was as low as 5ppb.In the present work, the SnO2/graphene nanocomposite composed of 4–5nm SnO2 nanoparticles was synthesized using a simple wet chemical method for ppb-level detection of benzene. The formation mechanism of the nanocomposite was investigated systematically by means of simultaneous thermogravimetry analysis, X-ray diffraction, and X-ray photoelectron spectroscopy cooperated with transmission electron microscopy observations. The SnO2/graphene nanocomposite showed a very attractive improved sensitivity to toxic volatile organic compounds, especially to benzene, compared to a traditional SnO2. The responses of the nanocomposite to benzene were a little higher than those to ethanol and the detection limit reached 5ppb to benzene which is, to our best knowledge, far lower than those reported previously.

Keywords: SnO; 2; /graphene nanocomposite; SnO; 2; nanoparticles; Benzene; Trace detection


Preparation of methacrylate-based anion-exchange monolithic microbore column for chromatographic separation of DNA fragments and oligonucleotides by Akhmad Sabarudin; Junchao Huang; Shin Shu; Shinnosuke Sakagawa; Tomonari Umemura (pp. 108-114).
Display Omitted► Microbore-scale (1mm i.d.) anion-exchange monolithic column. ► Potentially preparative applications. ► Separation of oligodeoxythymidylic acids and DNA fragments.In this paper, we report on the preparation of a microbore-scale (1mm i.d.) anion-exchange monolithic column suitable not only for analytical purposes but also for potentially preparative applications. In order to meet the conflicting requirements of high permeability and good mechanical strength, the following two-step procedure was applied. First, an epoxy-containing monolith was synthesized by in situ copolymerization of glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) within the confines of a silicosteel tubing of 1.02mm i.d. and 1/16″ o.d. in the presence of a ternary porogenic mixture of 1-propanol, 1,4-butanediol, and water. The monolithic matrix was subsequently converted into weak anion-exchanger via the ring-opening reaction of epoxy group with diethyl amine. The dynamic binding capacity was 21.4mgmL−1 for bovine serum albumin (BSA) at 10% breakthrough. The morphology and porous structure of this monolith were assessed by scanning electron microscope (SEM) and inverse size exclusion chromatography (ISEC). To optimize the separation efficiency, the effects of various chromatographic parameters upon the separation of DNA fragments were investigated. The resulting monolithic anion exchanger demonstrated good potential for the separation of both single- and double-stranded DNA molecules using a gradient elution with NaCl in Tris–HCl buffer (20mM). Oligodeoxythymidylic acids (dT12–dT18) were successfully resolved at pH 8, while the fragments of 20bp DNA ladder, 100bp DNA ladder, and pBR322-HaeIII digest were efficiently separated at pH 9.

Keywords: Monolithic column; Microbore column; Glycidyl methacrylate; Anion-exchange liquid chromatography; DNA; Oligodeoxythymidylic acids
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