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Analytica Chimica Acta (v.632, #2)

Editorial Board (pp. i).

Electrochemiluminescence from Ru(bpy)32+ immobilized in poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)–poly(vinyl alcohol) composite films by Chunyan Sun; Wu Lu; Yanfang Gao; Jinghong Li (pp. 163-167).
Electrochemical behavior and electrogenerated chemiluminescence (ECL) of tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+) immobilized in poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)–poly(vinyl alcohol) (PEDOT/PSS–PVA) composite films via ion-exchange have been investigated with tripropylamine (TPA) as the co-reactant at a glassy carbon electrode. The immobilized Ru(bpy)32+ performed a surface-controlled electrode reaction. The Ru(bpy)32+ modified electrode showed a fast ECL response to TPA, and was used for the ECL detection of TPA with high sensitivity. The ECL intensity was linearly related to concentrations of TPA over the range from 0.50μmolL−1 to 0.80mmolL−1, and the detection limit was 0.10μmolL−1 (S/N=3). The as-prepared electrode exhibited good precision and long-term stability for TPA determination.

Keywords: Electrogenerated chemiluminescence; Tris(2,2′-bipyridyl)ruthenium(II); Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate); Tripropylamine; Electrochemiluminescence sensor


Analytical methods for determination of mycotoxins: A review by Nicholas W. Turner; Sreenath Subrahmanyam; Sergey A. Piletsky (pp. 168-180).
Mycotoxins are small (MW ∼700), toxic chemical products formed as secondary metabolites by a few fungal species that readily colonise crops and contaminate them with toxins in the field or after harvest. Ochratoxins and Aflatoxins are mycotoxins of major significance and hence there has been significant research on broad range of analytical and detection techniques that could be useful and practical. Due to the variety of structures of these toxins, it is impossible to use one standard technique for analysis and/or detection. Practical requirements for high-sensitivity analysis and the need for a specialist laboratory setting create challenges for routine analysis. Several existing analytical techniques, which offer flexible and broad-based methods of analysis and in some cases detection, have been discussed in this manuscript. There are a number of methods used, of which many are lab-based, but to our knowledge there seems to be no single technique that stands out above the rest, although analytical liquid chromatography, commonly linked with mass spectroscopy is likely to be popular. This review manuscript discusses (a) sample pre-treatment methods such as liquid–liquid extraction (LLE), supercritical fluid extraction (SFE), solid phase extraction (SPE), (b) separation methods such as (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrophoresis (CE) and (c) others such as ELISA. Further currents trends, advantages and disadvantages and future prospects of these methods have been discussed.

Keywords: Abbreviations; APCI; atmospheric pressure chemical ionization; BEN; Balkan Endemic Nephropathy; C-18; octadecylsilane column; CCα; decision limit [in food quality analysis]; CCβ; decision capability [in food quality analysis]; CE; capillary electrophoresis; CI-ELISA; competitive indirect enzyme linked immunosorbent assay; CO; 2; carbon dioxide; DAD; diode array detection; DNA; deoxyribonucleic acid; ECD; electron capture detection; ELISA; enzyme linked immunosorbent assay; ELSD; evaporative laser scattering detector; FAO; food and agricultural organisation; FI; flame ionisation; FID; flame ionisation detector; FD; fluorescence detection; FTIR; fourier transform infrared spectroscopy; GC; gas chromatography; GC–ECD; gas chromatography coupled with electron capture detection; GC–MS; gas chromatography–mass spectroscopy; HPLC; high performance liquid chromatography; HPLC–DAD; high performance liquid chromatography coupled with diode array detection; HPLC–ELSD; HPLC coupled with an evaporative laser scattering detector; HPLC–FD; high performance liquid chromatography coupled with fluorescence detection; HT-2; HT-2 toxin; IA; immuno affinity; IAC; immuno affinity columns; IARC; International Agency for Research on Cancer; IgG; antibody; LC–MS; liquid chromatography–mass spectrometry; LLC; liquid–liquid chromatography; LLE; liquid–liquid extractioin; LOD; limits of detection; LOQ; limits of quantification; MAbs; monoclonal antibodies; McAb; monoclonal antibody; MEECK; microemulsion electrokinetic chromatography; MIP; molecularly imprinted polymers; MS; mass spectroscopy; MW; molecular weight; nano-RP-HPLC–ESI–MS; nano-reversed-phase HPLC–electrospray ionization–mass spectrometry; NICI; negative ion chemical ionisation; NIP; non-imprinted polymer; OPA; o; -phthaldialdehyde; PCA; principal component analysis; pH; power of hydrogen; PLS; partial least squares; ppb; parts per billion; ppm; parts per million; RNA; ribonucleic acid; RP; reverse phase; SAX; strong anion exchange; SFE; supercritical fluid extraction; SIIA; sequential injection immunoassay; SPE; solid phase extraction; SPME; solid phase microextraction; SPME–LC–MS/MS; solid phase micro extraction- coupled with liquid chromatography–mass spectroscopy–mass spectroscopy; SPR; surface plasmon resonance; T-2; T-2 toxin; TLC; thin layer chromatography; TRL; time resolved luminescence; WHO; World Health Organisation; 15-ADON; 15-acetyl-deoxynivalenol; 3-ADON; 3-acetyl-deoxynivalenol; aka; Vomitoxin; AFB-1; Aflatoxin B1; AFM1; Aflatoxin-M1; AFT; Aflatoxin; BEA; beauvericin; CIT; citrinin; CPZ; cyclopiazonic acid; DAS; diacetoxyscirpenol; DDB; 1,2-diamino-4,5-dichlorobenzene; DES; diethylstilbestrol; DHES; dihydroergosine; DIS; diphenylindenone sulphonyl ester of trichothecene mycotoxins; DON; deoxynivalenol; FB1; fuminosin B1; FB2; fuminosin B2; MPA; mycophenolic acid; NIV; nivalenol; OTA; ochratoxin; PAT; patulin; STE; sterigmatocystin; TRC; trichothecenes; ZEA; zearalone; ZEL; zearalenol; Zeranol; zearalanol; ZON; zearalanoneMycotoxins; Aflatoxin; Ochratoxin; High performance liquid chromatography; Liquid–liquid extraction; Gas chromatography; Thin layer chromatography; Enzyme linked immunosorbent assay


A review on speciation of iodine-129 in the environmental and biological samples by Xiaolin Hou; Violeta Hansen; Ala Aldahan; Göran Possnert; Ole Christian Lind; Galina Lujaniene (pp. 181-196).
As a long-lived beta-emitting radioisotope of iodine,129I is produced both naturally and as a result of human nuclear activities. At present time, the main part of129I in the environment originates from the human nuclear activity, especially the releases from the spent nuclear fuel reprocessing plants, the129I/127I ratios have being reached to values of 10−10 to 10−4 in the environment from 10−12 in the pre-nuclear era. In this article, we review the occurrence, sources, inventory, and concentration level of129I in environment and the method for speciation analysis of129I in the environment. Measurement techniques for the determination of129I are presented and compared. An overview of applications of129I speciation in various scientific disciplines such as radiation protection, waste depository, and environmental sciences is given. In addition, the bioavailability and radiation toxicity (dose to thyroid) of129I are discussed.

Keywords: Abbreviations; AMS; accelerator mass spectrometry; AmAD; activity median aerodynamic diameter; DIT; diiodotyrosine; DRC; dynamic collision/reaction cell; EXAFS; extended X-ray absorption fine structure spectra; HpGe; high purity germanium; HPLC; high performance liquid chromatography; ICP-MS; inductively coupled plasma mass spectrometry; LSC; liquid scintillation counter; MIT; monoiodothyrosine; NAA; neutron activation analysis; SIMS; secondary ion mass spectrometry; T; 3; triiodothyronine; rT; 3; reverse-triiodothyronine; T; 4; thyroxine; TBAH; tetrabutylammoniumhydroxide; TEDA; triethylenediamine; TBP/OK; tri-; n; -butyl phosphate in odourless kerosene; XANES; X-ray absorption near-edge structureIodine-129; Speciation analysis; Tracer; Bioavailability; Environmental sample


Ultrasensitive detection of TNT in soil, water, using enhanced electrogenerated chemiluminescence by Tommie L. Pittman; Bethtrice Thomson; Wujian Miao (pp. 197-202).
The ultrasensitive detection of 2,4,6-trinitrotoluene (TNT) was accomplished on the basis of sandwich-type TNT immunoassay combined with electrogenerated chemiluminescence (ECL) technology. Biotinylated anti-TNT species were attached to the surface of 1-μm diameter streptavidin-coated magnetic beads (MB) and 10-μm diameter avidin-coated polystyrene microspheres/beads (PSB) pre-loaded with ECL labels (∼7 billion hydrophobic ruthenium(II) tris(2,2′-bipyridine) (RuII) molecules per bead) to form anti-TNT↔MB and anti-TNT↔PSB(RuII) conjugates, respectively. Sandwich-type PSB(RuII)↔anti-TNTanti-TNT↔MB aggregates were formed when PSB(RuII)↔anti-TNT was mixed with anti-TNT↔MB conjugates in the presence of analyte TNT and 2.0% bovine serum albumin blocking agent. The newly formed aggregates were magnetically separated from the aqueous reaction media and dissolved in acetonitrile containing 0.10M tri- n-propylamine ECL coreactant–0.055M trifluoroacetic acid–0.10M tetrabutylammonium tetrafluoroborate electrolyte. ECL as well as cyclic voltammetric measurements were carried out with a potential scan from 0 to 2.8V vs Ag/Ag+, and the integrated ECL intensity was found to be linearly proportional to the analyte TNT concentration over the range of 0.10–1000ppt (pgmL−1). The limit of detection (≤0.10±0.01ppb) is about 600× lower as compared with the most sensitive TNT detection method in the literature, and the absolute detection limit in mass (∼0.1pg) is only ∼0.5% of that from mass spectroscopy. The approach coupled with the standard addition method was applied to measure the TNT contaminations in soil and creek water samples collected from a military training base.

Keywords: 2,4,6-Trinitrotoluene (TNT); Immunoassay; Electrogenerated chemiluminescence


New and rapid analytical procedure for water content determination: Microwave accelerated Dean–Stark by Sébastien Veillet; Valérie Tomao; Franco Visinoni; Farid Chemat (pp. 203-207).
Development of new procedures in analytical chemistry is currently increasingly focussed on reducing the time, cost and energy to carry out routine analyses. The conventional Dean–Stark (CDS) distillation to determine the water content is one of the most commonly used analytical methods and uses large amounts of solvent and energy. A new microwave accelerated Dean–Stark (MADS) distillation is presented as an alternative procedure. Microwaves were applied to a mixture of toluene, Weflon stir bar and olives, and the corresponding water was collected in a Dean–Stark receiver. This procedure permits fast and efficient determination of the water content of olives. Reliability and reproducibility were evaluated using statistical analyses. Different matrices were then used with MADS and the results were compared to CDS. Water determination from olives with MADS was better than that with CDS in terms of energy saving, rapidity (10min versus 120min), reproducibility, and cleanliness.

Keywords: Microwave; Distillation; Dean–Stark; Water determination


Headspace in-drop derivatization of carbonyl compounds for their analysis by high-performance liquid chromatography-diode array detection by Aradhana K.K.V. Pillai; Khileshwari Gautam; Archana Jain; Krishna K. Verma (pp. 208-215).
A simple and rapid method has been reported for the determination of carbonyl compounds involving sample preparation by headspace single drop microextraction using 1-butanol as extraction solvent containing 2,4-dinitrophenylhydrazine for hydrazone formation, and direct transfer of the drop into the injector for high-performance liquid chromatography with diode array detection. An angle-cut polytetrafluoroethylene sleeve, 3mm×0.5mm, was fixed at the tip of the syringe needle and this allowed the use of 7μL drop of solvent drop for extraction and derivatization. The procedure has been optimized with respect to suitable solvent for headspace drop formation, drop volume, concentration of reagent, sample temperature, reaction time, and headspace-to-sample volume ratio. The method has been validated when rectilinear relationship was obtained between the amount of analyte and peak area ratio of hydrazones in the range 0.01–15mgL−1, the correlation coefficient over 0.996–0.999, and the limit of detection in the range 1.7–24.1μgL−1. Spiked real samples have been analyzed with adequate accuracy, and application has been demonstrated of the method for analysis of carbonyl compounds formed as oxidation products.

Keywords: Headspace single drop extraction; In-drop derivatization; Carbonyl compounds; 2,4-Dinitrophenylhydrazones; Liquid chromatography


Development of on-line single-drop micro-extraction sequential injection system for electrothermal atomic absorption spectrometric determination of trace metals by Aristidis N. Anthemidis; Ibrahim S.I. Adam (pp. 216-220).
A novel automatic sequential injection (SI) single-drop micro-extraction (SDME) system is proposed as versatile approach for on-line metal preconcentration and/or separation. Coupled to electrothermal atomic absorption spectrometry (ETAAS) the potentials of this SI scheme are demonstrated for trace cadmium determination in water samples. A non-charged complex of cadmium with ammonium diethyldithiophosphate (DDPA) was produced and extracted on-line into a 60μL micro-drop of di-isobutyl ketone (DIBK). The extraction procedure was performed into a newly designed flow-through extraction cell coupled on a sequential injection manifold. As the complex Cd(II)-DDPA flowed continuously around the micro-droplet, the analyte was extracting into the solvent micro-drop. All the critical parameters were optimized and offered good performance characteristics and high preconcentration ratios. For 600s micro-extraction time, the enhancement factor was 10 and the sampling frequency was 6h−1. The detection limit was 0.01μgL−1 and the precision (RSD at 0.1μgL−1 of cadmium) was 3.9%. The proposed method was evaluated by analyzing certified reference material.

Keywords: Sequential injection; Single-drop micro-extraction; Atomic spectrometry; Metal determination


Nuclear magnetic resonance and liquid chromatography–mass spectrometry combined with an incompleted separation strategy for identifying the natural products in crude extract by Dongmei Dai; Jiuming He; Ruixiang Sun; Ruiping Zhang; Haji Akber Aisa; Zeper Abliz (pp. 221-228).
NMR and LC–MS combined with an incompleted separation strategy were proposed to the simultaneous structure identification of natural products in crude extracts, and a novel method termed as NMR/LC–MS parallel dynamic spectroscopy (NMR/LC–MS PDS) was developed to discover the intrinsic correlation between retention time (Rt), mass/charge ( m/ z) and chemical shift ( δ) data of the same constituent from mixture spectra by the co-analysis of parallelly visualized multispectroscopic datasets from LC–MS and1H NMR. The extracted ion chromatogram (XIC) and1H NMR signals deriving from the same individual constituent were correlated through fraction ranges and intensity changing profiles in NMR/LC–MS PDS spectrum due to the signal amplitude co-variation resulted from the concentration variation of constituents in a series of incompletely separated fractions. NMR/LC–MS PDS was applied to identify 12 constituents in an active herbal extract including flavonol glycosides, which was separated into a series of fractions by flash column chromatography. The complementary spectral information of the same individual constituent in the crude extract was discovered simultaneously from mixture spectra. Especially, two groups of co-eluted isomers were identified successfully. The results demonstrated that NMR/LC–MS PDS combined with the incompleted separation strategy achieved the similar function of on-line LC–NMR–MS analysis in off-line mode and had the potential for simplifying and accelerating the analytical routes for structure identification of constituents in herbs or their active extracts.

Keywords: Nuclear magnetic resonance/liquid chromatography–mass spectrometry parallel dynamic spectroscopy; Incompleted separation strategy; Off-line analytical method; Natural products; Crude extract


Near-ultraviolet femtosecond laser ionization of dioxins in gas chromatography/time-of-flight mass spectrometry by Satoshi Yamaguchi; Fumiaki Kira; Yuki Miyoshi; Tomohiro Uchimura; Yuka Watanabe-Ezoe; Shin-ichi Zaitsu; Tomoko Imasaka; Totaro Imasaka (pp. 229-233).
Gas chromatography/multiphoton ionization/time-of-flight mass spectrometry (GC/MPI/TOF-MS) was applied to the trace analysis of polychlorinated dibenzo- p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). To determine the optimum wavelength for analysis of PCDD/Fs, the wavelength of the femtosecond laser utilized for multiphoton ionization was converted to near-ultraviolet status using stimulated Raman scattering. A femtosecond laser emitting at 300nm completely eliminated the background signal arising from the bleeding compounds generated from a stationary phase of the capillary column in GC.

Keywords: Gas chromatography; Multiphoton ionization; Time-of-flight mass spectrometry; Femtosecond laser; Polychlorinated dibenzo-; p; -dioxins and polychlorinated dibenzofurans


Mass-independent isotopic fractionation of tin in chemical exchange reaction using a crown ether by Frédéric Moynier; Toshiyuki Fujii; Philippe Telouk (pp. 234-239).
Tin isotopes were fractionated by the liquid–liquid extraction technique with a crown ether, dicyclohexano-18-crown-6. The isotopic ratios ofmSn/120Sn (m: 116, 117, 118, 119, 122 and 124) were measured by multi-collector inductively coupled plasma spectrometry (MC-ICP-MS) on a Nu Plasma 500 with a precision better than 0.05permilamu−1 on each isotopic ratio. Odd atomic mass isotopes (117Sn and119Sn) showed depletions compared to the even atomic mass isotopes (116Sn,118Sn,122Sn and124Sn). We show that this odd–even staggering property originates from the nuclear field shift effect. The contribution of the nuclear field shift effect to the observed isotope enrichment factor was estimated to be ∼35%.

Keywords: Mass-independent isotopic fractionation; Multi-collector inductively coupled plasma spectrometry; Sn isotopes; Field shift effect; Crown ether


Evaluation of substrate performance for a microbial diagnostic microarray using a four parameter ranking by Ursula Sauer; Levente Bodrossy; Claudia Preininger (pp. 240-246).
The impact of substrates for probe immobilization was studied using a microbial diagnostic microarray consisting of probes designed against the pmoA genes of methanotrophs and functionally related bacteria. The proprietary ARChip Epoxy was compared to seven epoxy-modified competitor slides, and one porous 3D, furthermore two substrates recommended for oligoprobes without description of the surface chemistry. The diagnostic microarray on Cel silylated aldehyde (CSS) slide was used as a reference for this comparison as it was actually used for assay development and validation. The suitability of binding chemistries for microarrays was evaluated by specificity, signal, and inter- and intra-slide precision and ranked accordingly. The performance of four epoxy substrates (ARChip Epoxy, Cel Epoxy, Corning Epoxy, sciChip) and Spot On slides has proved satisfactory and comparable to the reference Cel CSS in that inter-slide precision was between 8% and 18% CV, intra-slide precision below 30%, respectively. The four parameter ranking shows great promise of providing deeper insight in the performance of materials and protocols tested.

Keywords: Microbial diagnostic microarray; Microarray substrates; Immobilization; Ranking


Chemiluminometric enzyme-linked immunosorbent assays (ELISA)-on-a-chip biosensor based on cross-flow chromatography by Il-Hoon Cho; Eui-Hwan Paek; Young-Kee Kim; Joo-Ho Kim; Se-Hwan Paek (pp. 247-255).
A chemiluminometric biosensor system for point-of-care testing has been developed using an immuno-chromatographic assay combined with an enzyme (e.g., horseradish peroxidase) tracer that produces a light signal measurable on a simple detector. Cross-flow chromatography, a method previously investigated by our laboratory, was utilized in order to accomplish sequential antigen–antibody binding and signal generation. This enzyme-linked immunosorbent assay (ELISA) was effectively carried out on a plastic chip that was redesigned to simplify the fabrication process. To enhance the sensitivity, biotin–streptavidin capture technology was employed in preparing an immuno-strip that was then incorporated onto the chip in order to generate the ELISA-on-a-chip (EOC) biosensor. Samples containing cardiac troponin I (cTnI) were analyzed using the EOC. A chemiluminescent signal proportional to the analyte concentration was produced by adding a luminogenic substrate to the tracer enzyme complexed with the analyte on the chip. The luminescent signal was detected in a dark chamber mounted with a cooled charge-coupled device and the signal was converted to optical density for quantification. This EOC biosensor system was capable of detecting cTnI present in serum at concentrations as low as 0.027ngmL−1, 30 times lower than those measured using the conventional rapid test kit with colloidal gold as the tracer. In addition, the final data was acquired within 30s after the addition of the enzyme substrate, which was faster than the detection time required when using a colorimetric substrate with the same tracer enzyme.

Keywords: Chemiluminometric signal; Enzyme-linked immunosorbent immunoassay (ELISA)-on-a-chip; Biotin–streptavidin capture; Cardiac troponin I; Cooled charge-coupled device


Glycidyl methacrylate-co-N-vinyl-2-pyrrolidone coated polypropylene strips: Synthesis, characterization and standardization for dot-enzyme linked immunosorbent assay by Charu Tyagi; Lomas Tomar; Harpal Singh (pp. 256-265).
Glycidyl methacrylate and N-vinyl-2-pyrrolidone (GMA-co-NVP) copolymers with various GMA:NVP ratios were synthesized by solution polymerization technique in toluene using 2,2′-azobisisobutyronitrile (AIBN) as free radical initiator and dip coated onto polypropylene strips. The copolymer composition in polymeric coatings was confirmed by proton NMR spectroscopy. Various techniques like FTIR, SEM and contact angle were used for surface characterization of the polymer coatings. These polymer coated strips were evaluated and standardized for their application in dot-ELISA in two steps. In first step, specificity, sensitivity and reproducibility of the assay on developed polymer coated strips was evaluated through a model system using rabbit anti-goat IgG, goat anti-rabbit IgG and goat anti-rabbit IgG HRP (horseradish peroxidase)-conjugate. Polymer coating with GMA-NVP mol% ratio of 78:22 was able to detect rabbit anti-goat IgG antibody at a concentration as low as 2ngmL−1 with 1% BSA as blocking agent using antispecies IgG peroxidase conjugate diluted 1500 times. In the second step, the sensitivity and specificity of the developed system was established with human blood and finally used to identify the source of mosquito blood meal which is an important parameter in epidemiological studies, particularly in determining the role of mosquito in malaria transmission. The time duration of standardized assay with developed polymer coated strips was cut down to one hour compared to the 3–4h required in usual dot-ELISA.

Keywords: Dot-enzyme linked immunosorbent assay; Glycidyl methacrylate-co-N-vinyl-2-pyrrolidone; Blocking agents; Horseradish peroxidase conjugate; Mosquito blood meal


A highly sensitive enzyme immunoassay for evaluation of 2′-deoxycytidine plasma level as a prognostic marker for breast cancer chemotherapy by Ibrahim A. Darwish; Ashraf M. Mahmoud; Tarek Aboul-Fadl; Abdul-Rahman A. Al-Majed; Nasr Y. Khalil (pp. 266-271).
A highly sensitive competitive enzyme immunoassay (EIA) has been developed and validated for the determination of the plasma level of 2′-deoxycytidine (dCyd), the potential prognostic marker for breast cancer chemotherapy. This assay employed a monoclonal antibody that recognizes dCyd with a high specificity, and 5′-succinyl-dCyd (5′sdCyd) conjugate of bovine serum albumin (5′sdCyd–BSA) immobilized onto microplate wells as a solid phase. The assay involved a competitive binding reaction between dCyd, in plasma sample, and the immobilized 5′sdCyd–BSA for the binding sites of the anti-dCyd antibody. The bound antibody was quantified with horseradish peroxidase-labeled anti-immunoglobulin second antibody and 3,3′,5,5′-tetramethylbenzidine as a peroxidase substrate. The concentration of dCyd in the sample was quantified by its ability to inhibit the binding of the antibody to the immobilized 5′sdCyd–BSA and subsequently the color formation in the assay. The assay limit of detection was 8nM and the effective working range at relative standard deviations (R.S.D.s) of ≤10% was 20–800nM. No cross-reactivity from the structurally related nucleobases, nucleosides, and nucleotides was observed in the proposed assay. Mean analytical recovery of added dCyd was 98–100±3.2–8.2%. The precision of the assay was satisfactory; R.S.D. was 3.4–4.2 and 4.3–8.9% for intra- and inter-assay precision, respectively. The proposed EIA was compared favorably with HPLC method in its ability to accurately measure dCyd spiked into plasma samples. The analytical procedure is convenient, and one can analyze 200 samples per working day, facilitating the processing of large-number batch of samples. The proposed EIA is expected to contribute in further evaluation of dCyd as a prognostic marker for breast cancer chemotherapy and elucidation of the role of dCyd in various biological and biochemical systems.

Keywords: 2′-Deoxycytidine; Breast cancer; Prognostic marker; Competitive binding; Enzyme immunoassay


Chemically-modified activated carbon with ethylenediamine for selective solid-phase extraction and preconcentration of metal ions by Zhenhua Li; Xijun Chang; Xiaojun Zou; Xiangbing Zhu; Rong Nie; Zheng Hu; Ruijun Li (pp. 272-277).
A new method that utilizes ethylenediamine-modified activated carbon (AC-EDA) as a solid-phase extractant has been developed for simultaneous preconcentration of trace Cr(III), Fe(III), Hg(II) and Pb(II) prior to the measurement by inductively coupled plasma optical emission spectrometry (ICP-OES). The new sorbent was prepared by oxidative surface modification. Experimental conditions for effective adsorption of trace levels of Cr(III), Fe(III), Hg(II) and Pb(II) were optimized with respect to different experimental parameters using batch and column procedures in detail. The optimum pH value for the separation of metal ions simultaneously on the new sorbent was 4.0. Complete elution of absorbed metal ions from the sorbent surface was carried out using 3.0mL of 2% (%w/w) thiourea and 0.5molL−1 HCl solution. Common coexisting ions did not interfere with the separation and determination of target metal ions. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 39.4, 28.9, 60.5 and 49.9mgg−1 for Cr(III), Fe(III), Hg(II) and Pb(II), respectively. The time for 94% adsorption of target metal ions was less than 2min. The detection limits of the method was found to be 0.28, 0.22, 0.09 and 0.17ngmL−1 for Cr(III), Fe(III), Hg(II) and Pb(II), respectively. The precision (R.S.D.) of the method was lower 4.0% ( n=8). The prepared sorbent as solid-phase extractant was successfully applied for the preconcentration of trace Cr(III), Fe(III), Hg(II) and Pb(II) in natural and certified samples with satisfactory results.

Keywords: Modified activated carbon; Ethylenediamine; Metal ions; Solid-phase extraction; Inductively coupled plasma optical emission spectrometry


Development of high performance liquid chromatography method for lacidipine in rabbit serum: Application to pharmacokinetic study by Ramesh Gannu; Vamshi Vishnu Yamsani; Chinna Reddy Palem; Shravan Kumar Yamsani; Madhusudan Rao Yamsani (pp. 278-283).
A simple and sensitive high performance liquid chromatographic (HPLC) method for quantification of lacidipine (LCDP) in rabbit serum was developed and validated. LCDP and internal standard (IS), felodipine were extracted into n-hexane and dichloromethane (70:30) solvent system and separated using an isocratic mobile phase, on an Inertsil C18 column. The effluent was monitored by UV detector at 240nm and at a flow rate of 1.0mLmin−1. The linearity range of proposed method was 1–500ngmL−1. The intra-day and inter-day coefficient of variation and percent error values of the assay method were less than 15% and mean recovery was more than 94 and 95% for LCDP and IS, respectively and the method was found to be precise, accurate, and specific during the study. The method was successfully applied for pharmacokinetic study of lacidipine after application of LCDP microemulsion gel in rabbits.

Keywords: Lacidipine; Reversed phase high performance liquid chromatography; Rabbit serum; Pharmacokinetics


A simplified version of the total kjeldahl nitrogen method using an ammonia extraction ultrasound-assisted purge-and-trap system and ion chromatography for analyses of geological samples by Fernanda V.M. Pontes; Manuel C. Carneiro; Delmo S. Vaitsman; Genilda P. da Rocha; Lílian I.D. da Silva; Arnaldo A. Neto; Maria Inês C. Monteiro (pp. 284-288).
The total Kjeldahl nitrogen (TKN) method was simplified by using a manifold connected to a purge-and-trap system immersed into an ultrasonic (US) bath for simultaneous ammonia (NH3) extraction from many previously digested samples. Then, ammonia was collected in an acidic solution, converted to ammonium (NH4+), and finally determined by ion chromatography method. Some variables were optimized, such as ultrasonic irradiation power and frequency, ultrasound-assisted NH3 extraction time, NH4+ mass and sulfuric acid concentration added to the NH3 collector flask. Recovery tests revealed no changes in the pH values and no conversion of NH4+ into other nitrogen species during the irradiation of NH4Cl solutions with 25 or 40kHz ultrasonic waves for up to 20min. Sediment and oil free sandstone samples and soil certified reference materials (NCS DC 73319, NCS DC 73321 and NCS DC 73326) with different total nitrogen concentrations were analysed. The proposed method is faster, simpler and more sensitive than the classical Kjeldahl steam distillation method. The time for NH3 extraction by the US-assisted purge-and-trap system (20min) was half of that by the Kjeldahl steam distillation (40min) for 10 previously digested samples. The detection limit was 9μgg−1N, while for the Kjeldahl classical/indophenol method was 58μgg−1N. Precision was always better than 13%. In the proposed method, carcinogenic reagents are not used, contrarily to the indophenol method. Furthermore, the proposed method can be adapted for fixed-NH4+ determination.

Keywords: Nitrogen; Sandstone; Sediment; Soil; Ion chromatography; Ultrasound-assisted purge-and-trap system


Application of dispersive liquid–liquid microextraction for the analysis of triazophos and carbaryl pesticides in water and fruit juice samples by Lingyan Fu; Xiujuan Liu; Jia Hu; Xinna Zhao; Huili Wang; Xuedong Wang (pp. 289-295).
In this work, a simple, rapid and sensitive sample pretreatment technique, dispersive liquid–liquid microextraction (DLLME) coupled with high performance liquid chromatography-fluorescence detection (HPLC-FLD), has been developed to determine carbamate (carbaryl) and organophosphorus (triazophos) pesticide residues in water and fruit juice samples. Parameters, affecting the DLLME performance such as the kind and volume of extraction and dispersive solvents, extraction time and salt concentration, were studied and optimized. Under the optimum extraction conditions (extraction solvent: tetrachloroethane, 15.0μL; dispersive solvent: acetonitrile, 1.0mL; no addition of salt and extraction time below 5s), the performance of the proposed method was evaluated. The enrichment factors for the carbaryl and triazophos were 87.3 and 275.6, respectively. The linearity was obtained in the concentration range of 0.1–1000ngmL−1 with correlation coefficients from 0.9991 to 0.9999. The limits of detection (LODs), based on signal-to-noise ratio (S/N) of 3, ranged from 12.3 to 16.0pgmL−1. The relative standard deviations (RSDs, for 10ngmL−1 of carbaryl and 20ngmL−1 of triazophos) varied from 1.38% to 2.74% ( n=6). The environmental water (at the fortified level of 1.0ngmL−1) and fruit juice samples (at the fortified level of 1.0 and 5.0ngmL−1) were successfully analyzed by the proposed method, and the relative recoveries of them were in the range of 80.4–114.2%, 89.8–117.9% and 86.3–105.3%, respectively.

Keywords: Dispersive liquid–liquid microextraction; Organophosphate; Carbamate; Fruit juice; Water analysis


Biopartitioning micellar chromatography to predict blood to lung, blood to liver, blood to fat and blood to skin partition coefficients of drugs by Y. Martín-Biosca; S. Torres-Cartas; R.M. Villanueva-Camañas; S. Sagrado; M.J. Medina-Hernández (pp. 296-303).
Biopartitioning micellar chromatography (BMC), a mode of micellar liquid chromatography that uses micellar mobile phases of Brij35 in adequate experimental conditions, has demonstrated to be useful in mimicking the drug partitioning process into biological systems. In this paper, the usefulness of BMC for predicting the partition coefficients from blood to lung, blood to liver, blood to fat and blood to skin is demonstrated. PLS2 and multiple linear regression (MLR) models based on BMC retention data are proposed and compared with other ones reported in bibliography. The proposed models present better or similar descriptive and predictive capability.

Keywords: Partition coefficients; Blood to lung; Blood to fat; Blood to liver; Blood to skin; Biopartitioning micellar chromatography


Purge efficiency in the determination of trihalomethanes in water by purge-and-trap gas chromatography by Francisco Ruiz-Bevia; Maria J. Fernandez-Torres; Maria P. Blasco-Alemany (pp. 304-314).
Purge-and-trap gas chromatography–mass spectrometry (PT-GC–MS) has become an accepted method for the analysis of trihalomethanes (THMs) in water. The purge-and-trap technique is based on an efficient transfer of volatile organic compounds from the liquid (contained in the purge chamber) to the gaseous phase by bubbling with an inert gas. The aim of this work was to study the purge system's efficiency by means of several consecutive purge cycles lasting 11min each of the same liquid sample. The concentration range chosen of THMs was very wide [5–200μgL−1]. The inert gas flow rate was 40mLmin−1, and experiments were performed at temperatures of 25, 35 and 50°C. Bromoform (CHBr3), the least volatile compound, needed 19 cycles to be purged quantitatively at a concentration of 200μgL−1 and only 7 cycles at 5μgL−1 for a 25mL sample at 25°C. Chloroform (CHCl3), the most volatile compound, required 4 cycles to be fully extracted at 200μgL−1 and 2 at 5μgL−1. Finally, Novak's theoretical model, based on the distribution constant between gas and liquid phases, was used to correlate the THMs purging extraction data.

Keywords: Trihalomethanes; Purge efficiency; Purge-and-trap; Effective distribution constant
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