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Analytica Chimica Acta (v.623, #1)
Review of molecular modification techniques for improved detection of biomolecules by mass spectrometry by Aki Honda; Yoshio Suzuki; Koji Suzuki (pp. 1-10).
After a soft ionizing method was established, MS (mass spectrometry) has become a more common tool in biochemistry because soft ionization made it possible to detect large molecules such as proteins. Many kinds of applications were established to further utilize MS for the identification or quantitation of biomolecules. In this review, we introduce recent applications with special focus on chemical modification techniques and chemical probes developed for the MS determination of biomolecules.
Keywords: Mass spectrometry; Chemical modification; Mass probe; Biomolecules
Development of a method for analysis of Iranian damask rose oil: Combination of gas chromatography–mass spectrometry with Chemometric techniques by Mehdi Jalali-Heravi; Hadi Parastar; Hassan Sereshti (pp. 11-21).
Gas chromatography–mass spectrometry (GC–MS) combined with Chemometric resolution techniques were proposed as a method for the analysis of volatile components of Iranian damask rose oil. The essential oil of damask rose was extracted using hydrodistillation method and analyzed with GC–MS in optimized conditions. A total of 70 components were identified using similarity searches between mass spectra and MS database. This number was extended to 95 components with concentrations higher than 0.01% accounting for 94.75% of the total relative content using Chemometric techniques. For the first time in this work, an approach based upon subspace comparison is used for determination of the chemical rank of GC–MS data. The peak clusters were resolved using heuristic evolving latent projection (HELP) and multivariate curve resolution-alternating least square (MCR-ALS) by applying proper constraints, and the combination of both methods for some cases. It is concluded that a thorough analysis of the complex mixtures such as Iranian damask rose requires sophisticated GC–MS coupled with the Chemometric techniques.
Keywords: Gas chromatography–mass spectrometry; Chemometric resolution techniques; Damask rose; Essential oils; Subspace comparison
Calibration model transfer for near-infrared spectra based on canonical correlation analysis by Wei Fan; Yizeng Liang; Dalin Yuan; Jiajun Wang (pp. 22-29).
In order to solve the calibration transformation problem in near-infrared (NIR) spectroscopy, a method based on canonical correlation analysis (CCA) for calibration model transfer is developed in this work. Two real NIR data sets were tested. A comparative study between the proposed method and piecewise direct standardization (PDS) was conducted. It is shown that the transfer results obtained with the proposed method based on CCA were better than those obtained by PDS when the subset had sufficient samples.
Keywords: Calibration transfer; Near-infrared spectroscopy; Canonical correlation analysis; Piecewise direct standardization
Model based substrate set point control of yeast cultivation processes based on FIA measurements by Christine Klockow; Dirk Hüll; Bernd Hitzmann (pp. 30-37).
In this contribution a model based substrate control system for Saccharomyces cerevisiae fed batch cultivations is presented. The intention is to keep the concentration of the substrate glucose at a fixed selected set point during the process run. Set points of 0.07gL−1 and 0.5gL−1 are chosen, as the cells change their metabolism from pure oxidative to oxidative–reductive depending on the glucose concentration. The precise control of glucose concentration during cultivations still poses a challenge as the analysis with available on-line measurement systems still has the problem of noise and a time delay of at least 6min. To compensate these effects a control system based on an ordinary FIA system for glucose measurements complemented by an extended Kalman filter is employed. The Kalman filter could handle the dynamics of the process accurately. Based on the glucose measurement every 3min it estimated the biomass and glucose concentration as well as the growth rate factor and the volume of the culture broth. Utilising the estimated values of the process variables a feed forward controller was complemented by a PI controller to adjust the glucose concentration at the desired set points. During the control phase the standard deviation of the measurements are 0.002gL−1 and 0.022gL−1 for the set points of 0.07gL−1 and 0.5gL−1, respectively.
Keywords: Estimation; Fed-batch cultivation; Flow injection analysis (FIA); Kalman filter; Substrate control; Yeast; Time delay compensation
Bilinear least squares (BLLS) and molecular fluorescence in the quantification of the propranolol enantiomers by Patrícia Valderrama; Ronei Jesus Poppi (pp. 38-45).
The quantification of mixtures of (R)- and (S)-propranolol (PRO) in the pure form and in the pharmaceutical preparations is described. The methodology is based on chiral recognition of propranolol by formation of an inclusion complex with β-cyclodextrin (CD), a chiral auxiliary, in the presence of 1-butanol. The excitation–emission fluorescence surface and second-order multivariate calibration such as bilinear least squares (BLLS) and parallel factor analysis (PARAFAC) were used in the model development. BLLS performed better than PARAFAC, presenting relative mean error in the order of 3.5%, analytical sensitivity of 0.07% and 0.08%, detection limit of 0.23% and 0.28% and quantification limit of 0.71% and 0.84% for the pure form and pharmaceutical preparations, respectively. These results indicate that the proposed methodology can be an alternative for the determination of propranolol enantiomeric composition.
Keywords: Bilinear least squares; Parallel factor analysis; Enantiomeric composition; Fluorescence spectroscopy; Figures of merit
Selective extraction, separation and speciation of iron in different samples using 4-acetyl-5-methyl-1-phenyl-1 H-pyrazole-3-carboxylic acid by Şerife Saçmacı; Şenol Kartal (pp. 46-52).
A method for speciation, preconcentration and separation of Fe(II) and Fe(III) in different matrices was developed using solvent extraction and flame atomic absorption spectrometry. 4-Acetyl-5-methyl-1-phenyl-1 H-pyrazole-3-carboxylic acid (AMPC) was used as a new complexing reagent for Fe(III). The Fe(III)–AMPC complex was extracted into methyl isobutyl ketone (MIBK) phase in the pH range 1.0–2.5, and Fe(II) ion remained in aqueous phase at all pH. The chemical composition of the Fe(III)–AMPC complex was determined by the Job's method. The optimum conditions for quantitative recovery of Fe(III) were determined as pH 1.5, shaking time of 2min, 1.64×10−4molL−1 AMPC reagent and 10mL of MIBK. Furthermore, the influences of diverse metal ions were investigated. The level of Fe(II) was calculated by difference of total iron and Fe(III) concentrations. The detection limit based on the 3 σ criterion was found to be 0.24μgL−1 for Fe(III). The recoveries were higher than 95% and relative standard deviation was less than 2.1% ( N=8). The validation of the procedure was performed by the analysis of two certified standard reference materials. The presented method was applied to the determination of Fe(II) and Fe(III) in tap water, lake water, river water, sea water, fruit juice, cola, and molasses samples with satisfactory results.
Keywords: Speciation; Fe(III)/Fe(II); Solvent extraction; Preconcentration; MIBK
Chemical switch based reusable dual optoelectronic sensor for nitrite by V. Vishnuvardhan; R. Kala; T. Prasada Rao (pp. 53-58).
An optical sensor was developed for sensing of nitrite based on the monotonous decrease in absorbance of Rhodamine 6G at 525nm (the absorbance maximum of dye) with increasing concentration of nitrite. This sensor also permits naked eye detection. Various parameters like concentrations of sulphuric acid and Rhodamine 6G, response time and stability were varied and optimal conditions are reported. Under these conditions, the developed sensor enables the determination of nitrite in the concentration range 0–12.18μmolL−1. The nitrite response is selective as 60–2.5×105 fold amounts of several anions and cations have no deleterious effect. The addition of nitrite to Rhodamine 6G dye causes hypsochromic shift from 525 to 385nm while several other anions like I−, SCN−, ClO4−, [HgI4]2− and [Zn (SCN)4]2− showed a bathochromatic shift from 525 to 575nm. The sequential addition of nitrite and sulphamic to Rhodamine 6G in 0.75molL−1 sulphuric acid solution results in switching of “ON” and “OFF” absorbance. The time elapse and concentration of sulphamic acid required for chemical switching was also established. Similar “ON” and “OFF” switching behaviour was observed in fluorescence studies also. This enabled the design and development of reusable chemical switch based dual optoelectronic sensor, for monitoring of traces of nitrite in environmental and food samples. The plausible mechanism for above switching behaviour is also proposed.
Keywords: Dual optical sensor; Nitrite; Chemical switch; Natural waters; Food materials
Determination of gas phase triacetone triperoxide with aspiration ion mobility spectrometry and gas chromatography–mass spectrometry by Riikka-Marjaana Räsänen; Marjaana Nousiainen; Kaleva Peräkorpi; Mika Sillanpää; Lauri Polari; Osmo Anttalainen; Mikko Utriainen (pp. 59-65).
Aspiration ion mobility spectrometry (IMS) has been used for the first time to screen 3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexaoxacyclononane explosive, the most commonly known as triacetone triperoxide (TATP). Gaseous TATP was generated from synthesized solid compound, sublimed and directed to a portable chemical detection system comprised of an aspiration-type IMS detector and six semiconductor sensors. Different unknown TATP gas phase concentrations were produced and corresponding IMS and semiconductor responses were measured. The experimental concentrations were determined by gas chromatography–mass spectrometry (GC–MS). The results evidenced that the monitored compound in the gas phase was TATP. In addition, the determined TATP concentrations and corresponding IMS intensities showed that the IMS response values were proportional to the measured TATP concentrations.
Keywords: Aspiration ion mobility spectrometry; Improvised explosives; Triacetone triperoxide; Semiconductor sensor
Monitoring of influenza virus hemagglutinin in process samples using weak affinity ligands and surface plasmon resonance by Carl-Fredrik Mandenius; Ronghui Wang; Anna Aldén; Gunnar Bergström; Sabine Thébault; Charles Lutsch; Sten Ohlson (pp. 66-75).
Surface plasmon resonance (SPR) was used to screen the interaction between a variety of affinity ligands and hemagglutinin (HA) from human influenza virus, with the aim of identifying low affinity ligands useful for the development of a rapid bioanalytical sensor. Three sialic acid-based structures and four lectins were evaluated as sensor ligands. The sialic acid-based ligands included a natural sialic acid-containing glycoprotein, human α1-acid glycoprotein (α1-AGP), and two synthetic 6′-sialyllactose-conjugates, with varying degree of substitution. The interaction of HA with the four lectin-based ligands, concanavalin A (Con A), wheat germ agglutinin (WGA), Maackia amurensis lectin (MAL), and Sambucus nigra agglutinin (SNA), showed a wide variation of affinity strengths. Affinity and kinetics data were estimated. Strong affinities were observed for Con A, WGA, α1-AGP, and a 6′-sialyllactose-conjugate with a high substitution degree, and low affinities were observed for MAL and a 6′-sialyllactose-conjugate with low substitution.The main objective, to identify a low affinity ligand which could be used for on-line monitoring and product quantification, was met by a 6′-sialyllactose–ovalbumin conjugate that had 0.6mol ligand per mol carrier protein. The apparent affinity of this ligand was estimated to be 1.5±0.03μM ( KD) on the SPR surface. Vaccine process samples containing HA were analyzed in the range 10–100μgHAmL−1 and correlated with single-radial immunodiffusion. The coefficient of variation on the same chip was between 0.010 and 0.091.
Keywords: Influenza virus hemagglutinin; Affinity ligand; Surface plasmon resonance; Low affinity; Weak affinity
Development of disposable bulk-modified screen-printed electrode based on bismuth oxide for stripping chronopotentiometric analysis of lead (II) and cadmium (II) in soil and water samples by Rashid O. Kadara; Ibtisam E. Tothill (pp. 76-81).
A bulk-modified screen-printed carbon electrode characterised for metal ion detection is presented. Bismuth oxide (Bi2O3) was mixed with graphite-carbon ink to obtain the modified electrode. The best composition was 2% Bi2O3 (wt%) in the graphite-carbon ink. The modified electrode with onboard screen-printed carbon counter and silver–silver chloride pseudo-reference electrodes exhibited good performance in the electrochemical measurement of lead (II) and cadmium (II). The electrode displayed excellent linear behaviour in the concentration range examined (20–300μgL−1) with limits of detection of 8 and 16μgL−1 for both lead (II) and cadmium (II), respectively. The analytical utility of the modified electrode was illustrated by the stripping chronopotentiometric determinations of lead (II) in soil extracts and wastewater samples.
Keywords: Bulk-modified screen-printed electrode; Bismuth oxide; Lead (II); Cadmium (II); Constant current stripping chronopotentiometry; Soil extracts; Wastewater
Synthesis of nano-pore samarium (III)-imprinted polymer for preconcentrative separation of samarium ions from other lanthanide ions via solid phase extraction by Simindokht Shirvani-Arani; Seyed Javad Ahmadi; Ali Bahrami-Samani; Mohammad Ghannadi-Maragheh (pp. 82-88).
A batch process was developed to separate samarium ions from some lanthanide ions by a novel solid phase which was prepared via the ion-imprinting technique. The samarium (III) ion-imprinted polymer (IIP) particles were synthesized by preparing the ternary complex of samarium ions with 5,7-dichloroquinoline-8-ol (DCQ) and 4-vinylpyridine (VP). Then, thermally copolymerization with styrene (functional monomer, STY) and divinylbenzene (cross-linking monomer, DVB) followed in the presence of 2-methoxy ethanol (porogen) and 2,2′-azobisisobutyronitrile (initiator, AIBN). The imprinted ion was removed by stirring the above particles with 50% (v/v) HCl to obtain the leached IIP particles. Moreover, control polymer (CP) particles were similarly prepared without the samarium ions. The unleached and leached IIP particles were characterized by X-ray diffraction (XRD), infra-red spectroscopy (IR), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). Finally, preconcentration and selectivity studies for samarium and the other lanthanide ions were carried out. The preconcentration of the samarium (III) traces was studied during rebinding with the leached IIP particles as a function of pH, the weight of the polymer material, the preconcentration and the elution times, the eluent volume and the aqueous phase volume. These studies indicated that the samarium (III) amount as low as 1μg, present in 200mL, could be preconcentrated into 25mL of 1.0M HCl.
Keywords: Ion-imprinted polymer; Samarium (III); Lanthanides; Solid phase extraction
Simultaneous determination of amiodarone and its metabolite desethylamiodarone by high-performance liquid chromatography with chemiluminescent detection by Tomás Pérez-Ruiz; Carmen Martínez-Lozano; María Dolores García-Martínez (pp. 89-95).
A novel method was developed for the determination of amiodarone and desethylamiodarone by high-performance liquid chromatography (HPLC) coupled with chemiluminescent (CL) detection. The procedure is based on the post-column photolysis of the analytes into photoproducts which are active in the tris(2,2′-bipyridyl)ruthenium(III) [Ru(bpy)33+] CL system. Ru(bpy)33+ was on-line generated by photo-oxidation of the Ru(II) complex in the presence of peroxydisulfate. The separation was carried out on a Mediterranea C18 column with isocratic elution using a mixture of methanol and 0.017molL−1 ammonium sulfate buffer of pH 6.8. Under the optimum conditions, analytical curves, based on standard solutions, were linear over the range 0.1–50μgmL−1 for amiodarone and 0.5–25μgmL−1 for desethylamiodarone. The detection limits of amiodarone and desethylamiodarone were 0.02 and 0.11μgmL−1, respectively. Intra- and inter-day precision values of 0.9% relative standard deviation (R.S.D.) ( n=10) and 1.6% R.S.D. ( n=15), respectively, were obtained. The method was applied successfully to the determination of these compounds in serum and pharmaceutical formulations.
Keywords: Amiodarone; Desethylamiodarone; High-performance liquid chromatography; Chemiluminescent detection; Photoderivatization; Tris(2,2′-bipyridyl)ruthenium(III)
Direct electrogenerated chemiluminescence detection in high-performance liquid chromatography for determination of ofloxacin by Yonghua Sun; Zhujun Zhang; Zhijun Xi (pp. 96-100).
Ofloxacin (OFLX) exhibited strong electrogenerated chemiluminescence (ECL) in NaNO3 solution with a dual-electrode system when constant current was exerted. Based on this observation, a sensitive direct ECL method coupled with high-performance liquid chromatography (HPLC) separation was developed for determination of OFLX in human serum. Factors affected the ECL emission were investigated. Under the optimal conditions, the ECL intensity has a linear relationship with the concentration of OFLX in the range of 1.0×10−8 to 4.0×10−6gmL−1 and the detection limit was 4×10−9gmL−1 (S/N=3). The proposed method was sensitive, simple and convenient to operate.
Keywords: Direct electrogenerated chemiluminescence; Liquid chromatography; Dual-electrode system; Ofloxacin
Development of a molecularly imprinted polymer for pyridoxine using an ion-pair as template by Taher Alizadeh (pp. 101-108).
One of the main challenges in the molecularly imprinted polymers (MIP) field is the proper MIP design for water-soluble compounds because of appearance of serious drawbacks in polar solvents and insolubility of those compounds in non-polar solvents which are commonly used for MIP synthesis. In this work a novel and simple method for synthesis of molecularly imprinted polymers for a water-soluble compound was introduced. Pyridoxine was chosen as a target molecule and the ion-pair complex formed between pyridoxine ion (Py+) and dodecyl sulfate ion (DS−) was transferred into the chloroform via liquid–liquid extraction. Then polymerization was carried out in chloroform. The molecular mechanics and density functional theory were proposed to screen proper monomer. Binding energy, Δ E, of a template and a monomer as a measure of their interaction was considered. Ion-pair [Py+-DS−] was supposed as a template molecule and acrylic acid, methacrylic acid, allyamine, vinylpridine and 2-hydroxy ethyl methacrylate were as tested monomers. The MIP synthesized using acrylic acid showed the highest selectivity to pyridoxine as predicted from the Δ E calculation. The obtained MIP showed very high affinity against vitamin B6 in comparison to non-imprinted polymers (NIP). It was proved that the obtained MIP with introduced method was much better than that prepared in methanol as porogen. It was showed that the MIP prepared by this new method could be used as an adsorber for extraction and determination of pyridoxine in real and synthetic samples.
Keywords: Molecularly imprinted polymer; Pyridoxine; Ion-pair
On-site determination of formaldehyde: A low cost measurement device for museum environments by L.T. Gibson; W.J. Kerr; A. Nordon; J. Reglinski; C. Robertson; L. Turnbull; C.M. Watt; A. Cheung; W. Johnstone (pp. 109-116).
A trapping reagent for formaldehyde, based on the pararosaniline reaction, was evaluated as a method of determination of formaldehyde in the aqueous or vapour phase. Collection of formaldehyde vapour relied upon passive diffusion of formaldehyde into the trapping media and quantitative results were obtained without the need for liquid impingers, bubblers or active sampling pumps. Moreover, a novel, hand-held absorption spectrophotometric measurement device was designed to provide on-site, quantitative measurements. It is proposed that the full measurement system devised would be ideally suited to specific sampling applications such as those found in museum enclosures.
Keywords: Formaldehyde; Schiff's base; Xerogels; Museum environments