Abstracts

Abstract

NOVEL IMIDAZOLE PVC‐BASED MEMBRANE SENSOR BASED ON 4‐METHYL‐2,6 DIPHENYLTHIOPYRYLIUM by M. Reza Ganjali and H. Pirelahi, Department of Chemistry, Tehran University, Tehran, Iran; M. Abdi and M. Reza Sohrabi, Department of Chemistry, Islamic Azad University, Branch of North, Tehran, Iran; and A. Moradzadegun, Department of Chemistry, Shahid Chamran University, Ahvaz, Iran

ABSTRACT: A novel poly(vinyl chloride) (PVC)‐based membrane sensor based on 4‐methyl‐2,6‐diphenylpyrylium perchlorate (MPPP) is presented. The best performance was obtained with a membrane containing 30% poly(vinyl chloride) (PVC), 53% plasticizer dibutyl phthalate (DBP), 7% ionophore MPPP and 10% oleic acid. The proposed membrane electrode responds to imidazole in a wide concentration range 1.0 × 10⁻⁵ to 1.0 × 10⁻¹ M, with a sub‐Nernstian slope of +36.2 ± 0.2 mV per decade of activity of imidazole. The detection limit of the sensor is 2.0 × 10⁻⁶ M and can be used for at least four weeks without any measurable change in sensitivity. The sensitivity of the electrode is high enough to permit the detection of as little as 0.15 µg/mL of imidazole without any significant interference from high levels of other components such as common cations and anions and specially, amino acids. The potentiometric selectivity coefficient data revealed negligible interference from common cations, inorganic and organic anions and amino acids. The electrode shows a relatively fast response time in whole concentration range (<30 s). The proposed membrane electrode was used for fast direct potentiometric monitoring of imidazole in synthetic serum samples.

Analytical Letters, 37(2), 179–190 (2004)

Abstract

USE OF A CYANINE DYE AS A REPORTER PROBE IN REAGENTLESS MALTOSE SENSORS BASED ON E. COLI MALTOSE BINDING PROTEIN by I. L. Medintz and J. M. Mauro, Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, Code 6910, 4555 Overlook Ave., SW, Washington DC 20375, USA

ABSTRACT: Reagentless bio‐sensing proteins represent a promising technology being developed for sensitive chemical detection and analysis. The majority of these sensor proteins incorporate environmentally sensitive UV‐excited fluorescent dyes as reporter probes. In this report, we describe conjugation of the commercially available visible wavelength‐excitable polymethine cyanine dye Cy3 (λ_maxabs = 556 nm; λ_maxem= 567 nm) to several single‐cysteine variants of maltose binding protein (MBP), followed by evaluation of each of these labeled proteins as potential reagentless sensors for maltose. Four of six MBP variants labeled with the Cy3 probe functioned successfully in a homogenous reagentless sensing mode, and yielded maltose dissociation constants ranging from 74 µM to 3.8 mM. Cy3 and other cyanine dye derivatives may be useful as long‐wavelength excitable reporter groups in other reagentless sensor designs.

Analytical Letters, 37(2), 191–202 (2004)

Abstract

A PVC‐BASED VANADYL PHOSPHATE MEMBRANE POTENTIOMETRIC SENSOR FOR VANADYL IONS by A. Akbari, M. F. Mousavi and M. S. Rahmanifar, Department of Chemistry, Tarbiat Modarres University, P.O. Box 14115‐111, Tehran, Iran; and M. Barzegar, Department of Food Science and Technology, Tarbiat Modarres University, Tehran, Iran

ABSTRACT: Poly(vinyl chloride) (PVC)‐based membrane of vanadyl phosphate has been fabricated using 2‐nitrophenyl octyl ether (NPOE) and 2‐nitrophenyl pentyl ether (NPPE), as plasticizing solvent mediators. The best sensor having composition ionophore:PVC:NPOE (wt.%) 10:55:35 exhibits linearity in the concentration range 1.0 × 10⁻⁶ – 1.0 × 10⁻¹ M with a Nernstian slope of 29.5 mV per decade of concentration. The static response time of the sensor is <5.0 s and it can be used for a period of 14 days without any divergence in potentials. The sensor performs satisfactorily between pH 2.0 and 4.0. It exhibits good selectivity over a number of cations and was used as an indicator electrode in the potentiometric titration of vanadyl ions with EDTA.

Analytical Letters, 37(2), 203–212 (2004)

Abstract

PREPARATION AND APPLICATION OF A NOVEL COMPOSITE NANOPARTICLE AS A PROTEIN FLUORESCENCE PROBE by L. Wang, H. Chen, L. Wang, L. Li, F. Xu, J. Liu, and C. Zhu, College of Chemistry and Material Science, Anhui Normal University, Wuhu 241000, P.R. China

ABSTRACT: A novel composite nanoparticle has been prepared by an in situ polymerization method under ultrasonic irradiation. The nano‐CdS has been prepared, then the polymerization of acrylic acid (AA) was carried out by initiator potassium persulfate (KPS) under ultrasonic irradiation. The surface of the composite nanoparticles was covered with abundant carboxylic groups (—COOH). The nanoparticles are water‐soluble, stable and biocompatible. The fluorescence intensity of the composite nanoparticles is significantly increased in the presence of micro protein at pH 5.50. Based on this, a new fluorescence probe was developed for the determination of proteins including BSA, HSA and human γ‐IgG. The fluorescence emission is measured at λ_em/λ_ex = 580/400 nm. Under the optimum conditions, the response is linearly proportional to the concentration of proteins. The liner range is 0.1–40 µg mL⁻¹ for BSA, 0.2–25 µg mL⁻¹ for HSA and 0.1–15 µg mL⁻¹ for human γ‐IgG. The method has been applied to the determination of the total protein in human serum samples collected from the hospital and the results are in good agreement with those reported by the hospital, which indicates that the method presented here is not only sensitive, simple, inexpensive but also reliable.

Analytical Letters, 37(2), 213–223 (2004)

Abstract

GOLD ELECTRODE MODIFIED WITH A SELF‐ASSEMBLED MONOLAYER OF 11‐AMINO‐1‐UNDECANETHIOL HYDROCHLORIDE FOR THE DETERMINATION OF ANIONIC SURFACTANTS by T. Masadome, A. Ueda, and M. Kawakami, Department of Chemical Science and Engineering, Ariake National College of Technology, Omuta, Fukuoka, Japan

ABSTRACT: Effect of anionic surfactants on the cyclic voltammetric response of Fe(CN)₆ ³⁻ at a gold electrode modified with self‐assembled monolayer (SAM) of 11‐amino‐1‐undecanethiol hydrochloride was examined. As the concentration of anionic surfactants increases, the currents of [Fe(CN)₆]³⁻ reduction decreases and cyclic voltammograms become irreversible. The currents of [Fe(CN)₆]³⁻ reduction depended on the concentration of anionic surfactants in the 10⁻⁶ M range.

Analytical Letters, 37(2), 225–233 (2004)

Abstract

A NOVEL INDIRECT SPECTROFLUORIMETRIC METHOD FOR THE ULTRA TRACE ANALYSIS OF A HIGHLY TOXIC METALLOID—ANTIMONY IN AQUEOUS MEDIUM AND ITS APPLICATION TO METALLURGICAL, MEDICINAL, AND BIOLOGICAL SAMPLES by S. Biswas, B. Chowdhury, and B. Chandra Ray, Department of Chemistry, Jadavpur University, Calcutta 700 032, India

ABSTRACT: An inexpensive, virtually specific, non‐extractive method for the determination of antimony (III) at trace and ultra trace levels (5 ng mL⁻¹–1 µg mL⁻¹) in 0.09–0.45 (M) sulphuric acid has been developed. A known excess of chromium (VI) is allowed to quantitatively oxidise antimony (III) in the presence of iodine as catalyst, followed by addition of known excess of murexide (ammonium purpurate), where the unreacted chromium (VI) quantitatively quenches the fluorescence of murexide in acid medium, and measurement of the fluorescence intensity (λ_ex = 336 nm, λ_em = 424 nm). The measurement is repeated without antimony (III) addition and the increase in fluorescence intensity gives the concentration of antimony (III) with the help of a calibration graph. The method is very precise and accurate (S.D = ± 0.2248 and R.S.D = 0.2249% for the determination of 0.1 µg mL⁻¹ of antimony (III) in 11 replicates). Relatively large excesses of over 35 cations and anions do not interfere. The method has been successfully applied for antimony determination in various complex matrices, certified reference materials (alloys), commercially available solder and lead samples, medicinal and biological samples.

Analytical Letters, 37(2), 235–246 (2004)

Abstract

SPECTROPHOTOMETRIC DETERMINATION OF BISACODYL AND PIRIBEDIL by M. H. Abdel‐Hay, S. M. Sabry, M. H. Barary, and T. S. Belal, Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, University of Alexandria, Alexandria, Egypt

ABSTRACT: Simple spectrophotometric methods are described for the assay of bisacodyl (BIS) and piribedil (PIR) based on charge‐transfer and ion‐pair complexation reactions. The first method is based on the reaction of the cited drugs with p‐chloranilic acid (p‐CA) in acetonitrile. The purple colored chromogen formed shows maximum absorbance at 518 nm. The second method is concerned with the reaction of the investigated drugs with picric acid (PA) and four sulphonphthalein acid dyes, namely; bromocresol green (BCG), bromocresol purple (BCP), bromophenol blue (BPB) and thymol blue (TB). The yellow ion‐pair complexes formed show absorption spectra with maxima within the range from 400 to 415 nm. The stoichiometric ratio was found to be 1:1, for all complexation reactions examined, as calculated by the continuous variations method. Beer's law validation, accuracy, precision, limits of detection, limits of quantification, and other aspects of analytical merit are presented in the text. The proposed methods were applied for the determination of the analytes in their pure forms and in pharmaceutical preparations. The results were in good agreement with those obtained by the official and reported methods.

Analytical Letters, 37(2), 247–262 (2004)

Abstract

IDENTIFICATION AND PURITY CONTROL OF THIOACRIDINE DERIVATIVES BY GAS AND CAPILLARY LIQUID CHROMATOGRAPHY WITH MASS SPECTROMETRIC DETECTION by B. Kutnerová, I. Jelínek, and I. Némcová, Charles University, Department of Analytical Chemistry, Albertov 2030, CZ‐128 43, Prague 2, Czech Republic; and M. Šticha, Charles University, Department of Organic Chemistry and Radiochemistry, Albertov 2030, CZ‐128 43 Prague 2, Czech Republic

ABSTRACT: Mass spectrometry combined with gas chromatography (GC‐MS) or capillary liquid chromatography (CLC‐MS) was successfully utilized for structural characterization and purity control of synthesized biologically active thioacridine derivatives. Obtained results document sufficient selectivity of GC‐MS and CLC‐MS towards structurally related impurities and degradation products accompanying the compound of desire in analyzed substances. Based on electron impact ionization mass spectra an attempt to estimate their exact structures was made. The results of structure elucidation were confirmed by more detailed fragmentation studies based on (MS)² and (MS)³ electrospray ionization mass spectra.

Analytical Letters, 37(2), 263–272 (2004)

Abstract

SIMULTANEOUS DETERMINATION OF GESTODENE AND ETHINYL ESTRADIOL IN CONTRACEPTIVE FORMULATIONS BY RP‐HPLC by A. Laban and S. Markovic, Institute of Pharmacy of Serbia, 11000 Belgrade; M. Stankov, Faculty of Pharmacy, V. Stepe 458, 11000 Belgrade; and Predrag Djurdjevic, Faculty of Science, Chemistry Department, R. Domanovica 12, p.o.b. 60, 34000 Kragujevac, Yugoslavia, State Union of Serbia and Montenegro

ABSTRACT: A rapid and simple HPLC method for the determination of gestodene (GTD) and ethinyl estradiol (ETE) in oral contraceptive formulations was developed and validated. Separation of components was achieved on Waters Symmetry Shield Rp‐18 column. Isocratic elution with a mobile phase consisting of methanol and water in a volume percent ratio 80:20 at a flow rate 1.0 mL/min was employed. The components were detected by UV detection at 220 nm. Ciproterone acetate was used as an internal standard (IS). Linear concentration range for GTD was between 0.01 and 0.2 mg/mL and for ETE between 0.005 and 0.08 mg/mL. The detection limit was 2.3 µg/mL for GTD and 0.80 µg/mL for ETE. Mean analytical recovery in determination of GTD and ETE in “Mirelle” (Schering, FRG) tablets was 102.8% for GTD and 101.3% for ETE. Thus, the proposed method is applicable for routine determination of GTD and ETE in contraceptive formulations.

Analytical Letters, 37(2), 273–282 (2004)

Abstract

DETERMINATION OF A NOVEL ANTIANGIOGENIC AGENT KR‐31831 IN RAT PLASMA BY LIQUID CHROMATOGRAPHY‐TANDEM MASS SPECTROMETRY by S. J. Kim, S.‐S. Lee, H. Y. Ji, H. I. Lee, and H. S. Lee, Drug Metabolism and Bioanalysis Laboratory, College of Pharmacy, Wonkwang University, Iksan 570‐749, Korea; S. Lee, K. Y. Yi, and S. E. Yoo, Medicinal Science Division, Korea Research Institute of Chemical Technology, Taejeon, 305‐600, Korea; and J. S. Hwang, Department of Chemistry, Daejeon University, Taejeon 300‐179, Korea

ABSTRACT: A liquid chromatography‐tandem mass spectrometric (LC/MS/MS) method was developed for the determination of a new anti‐angiogenic drug KR‐31831 in rat plasma. KR‐31831 and internal standard, KR‐31543 were extracted from rat plasma with dichloromethane at basic pH. A reverse‐phase LC separation was performed on Luna C8 column with the mixture of acetonitrile–ammonium formate (10 mM, pH 4.5) (67:33, v/v) as mobile phase. The detection of analytes was performed using an electrospray ionization tandem mass spectrometry in the multiple‐reaction‐monitoring mode. The standard curve was linear (r = 0.999) over the concentration range of 1.0–500 ng/ml. The coefficient of variation of intra‐ and inter‐assay ranged from 0.8–3.9% and 1.4–3.9%, respectively. The recoveries of KR‐31831 ranged from 80.9% to 86.7%, with that of KR‐31543 (internal standard) being 99.2 ± 2.7%. The lower limits of quantification for KR‐31831 was 1.0 ng/ml using 100 µl plasma sample. This method was applied to the pharmacokinetic study of KR‐31831 in rats.

Analytical Letters, 37(2), 283–292 (2004)

Abstract

EFFECT OF DIFFERENT SUBSTITUTED POSITION OF PHENYLCARBAMOYL‐‐CD ON THE ENANTIOSEPARATION OF DRUGS BY CAPILLARY ELECTROPHORESIS by C. Zhang, X. Lin, Y. Wei, and C. Zhu, School of Chemistry Shandong University, Jinan 250061, P.R. China

ABSTRACT: A number of acidic and basic chiral drugs such as β‐agonists, β‐antagonists and phenylethyamines were separated by capillary electrophoresis with mono‐3‐O‐phenylcarbamoyl‐β‐CD and mono‐6‐O‐phenylcarbamoyl‐β‐CD. The effects of the CD type and concentration and the pH of the background electrolyte on the resolution of the drugs bad been studied. The substituted position has a significant effect on the separation of chiral drugs and is therefore an important factor in the optimization of chiral resolution. Accordingly, a proper description of derived cyclodextrins should include substituted position.

Analytical Letters, 37(2), 293–305 (2004)

Abstract

AN ANALYTICAL APPLICATION OF OFLOXACIN BY SOLID‐SUBSTRATE ROOM TEMPERATURE PHOSPHORESCENCE by J. Li, Y. Wei, J. Li, X. Feng, and C. Dong, Institute of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, P.R. China

ABSTRACT: This article presents a new determination method for the analysis of ofloxacin (OFLX) by solid‐substrate room temperature phosphorescence (SS‐RTP) with filter paper as solid substrate and CdCl₂ as heavy‐atom salt. Various factors affecting RTP intensity of OFLX, such as heavy‐atom effect, pH and drying time of the sample, were studied in detail. The linear dynamic range (LDR), limit of detection and RSD were: 1.03–411 ng/spot, 0.123 ng/spot and 1.7% for ofloxacin, respectively. The method was applied to determine ofloxacin in urine successfully. The recoveries of OFLX in urine are from 94.60% to 105.4%. The pharmacokinetic of OFLX was studied in urine as well. Mean accumulative excretion rate is 77.69%.

Analytical Letters, 37(2), 307–320 (2004)

Abstract

SPECTROPHOTOMETRIC REACTION RATE METHOD FOR DETERMINATION OF OXALIC ACID IN FOOD BASED ON ITS ENHANCING EFFECT ON THE OXIDATION OF PYROCATHECOL VIOLET BY DICHROMATE by A. A. Ensafi and M. Emadi, College of Chemistry, Isfahan University of Technology, Isfahan 84156, Iran

ABSTRACT: A simple kinetic spectrophotometric method for the determination of oxalic acid has been described, based on its catalytic effect on the oxidation of pyrocathecol violet (PCV) with potassium dichromate in acidic media. The reaction was monitored photometrically by measuring the decrease in absorbance of pyrocathecol violet at 450 nm. The influence of acid, pyrocathecol violet concentration, dichromate concentration and temperature were studied and optimized completely. Under the optimum condition, a calibration graph from 0.08 to 1.3 µg/mL of oxalic acid with a detection limit of 0.07 µg/mL was obtained. The relative standard deviation for ten replicate measurement of 0.8 µg/mL oxalic acid is 0.8%. The proposed method is fast and simple. The applicability of the method was demonstrated by the determination of oxalic acid in wastewater, spinach and mushroom samples.

Analytical Letters, 37(2), 321–332 (2004)

Abstract

ON‐SITE DETERMINATION OF ARSENIC IN CONTAMINATED WATER by K. Shrivas and K. Singh Patel, School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur‐492010, CG, India

ABSTRACT: A new spectrophotometric method for the on‐site determination of arsenic in contaminated water samples has been developed. The method is simple, rapid and selective. It is based on reduction of As(V) to As(III) with ascorbic acid, complexation of As(III) with I⁻ ions in strong HCl medium and extraction of the yellow colored iodo‐complex with N‐octylacetamide (OAA) into chloroform solution. The optimum acidity range is 4.5–6.0 M HCl/2.5–3.5 M H₂SO₄. The apparent value (i.e., at two fold enrichment factor) of molar absorptivity in the term of arsenic is 5.00 × 10⁴ L mol⁻¹ cm⁻¹ at λ_max, 420 nm. The detection limit (i.e., absorbance causing more absorbance than 3 s) of the method is 10 µg L⁻¹ As. The method is free from interference of the ions commonly found to be associated with arsenic in environmental samples. The method has been tested for the field determination of arsenic in contaminated waters (i.e., surface, ground, rice field) of central India.

Analytical Letters, 37(2), 333–344 (2004)