Abstracts

Abstract

PHOSPHATE, NITRATE, AND SULFATE BIOSENSORS by A. Amine, Faculté des Sciences et Techniques, Université Hassan, II-Mohammedia, Morroco; G. Palleschi, Dipartamento di Scienza e Technologie Chimiche, Università di Roma, Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy

ABSTRACT: Construction and assembly of phosphate, nitrate, and sulfate biosensors has been reviewed to give readers up‐to‐date information on the state of the art in this area which is becoming more and more important for the solution of practical problems faced in the monitoring of food safety and the environment. Special attention was paid concerning the papers published during the last 5 years. This mini‐review was also written to stimulate scientists to put more effort into the development of phosphate, nitrate, and sulfate biosensors, these being at present the least developed types on which only a limited number of papers has been published.

Analytical Letters, 37(1), 1– 19 (2004)

Abstract

A NEW CESIUM ION SELECTIVE GRAPHITE ROD ELECTRODE BASED ON Cs‐MOLYBDOPHOSPHATE by H. A. M. Arida, R. F. Aglan, and S. A. El‐Reefy, Hot Laboratory Center, Atomic Energy Authority, 13759‐Cairo, Egypt

ABSTRACT: A new poly(vinyl chloride) (PVC) electrode for Cs⁺ ion based on Cs‐12‐molybdophosphate (Cs‐12‐MPO) as a membrane carrier is prepared and characterized. The electrode exhibits a linear response with slope of 46.5 ± 1 mV/decade within the concentration range of 1.0 × 10⁻⁵–1.0 × 10⁻¹ mol L⁻¹ Cs⁺ ion. The limit of detection was 3.0 × 10⁻⁶ mol L⁻¹.The proposed electrode shows a good selectivity for Cs⁺ ion over a wide variety of other metal ions and could be used in the pH range of 4.0–6.0. It has a relatively fast response time less than (30 s) and can be used for at least 3 weeks without any considerable divergence in potentials. The proposed electrode is applied as a sensor for the determination of Cs⁺ ion concentration in some samples. The results show a good correlation with the data obtained by atomic absorption spectrometric method. The average recovery obtained is 92% ± 0.5% with a standard deviation of 1.2%.

Analytical Letters, 37(1), 21–33 (2004)

Abstract

A POLY(VINYL CHLORIDE) MEMBRANE ELECTRODE FOR THE DETERMINATION OF THE DIURETIC FUROSEMIDE by I. L. Tescarollo Dias, G. de Oliveira Neto, D. C. Vendramini, and C. Sommer, Universidade São Francisco, UAACBS, Curso de Farmácia, Bragança Paulista, São Paulo, Brazil; J. L. S. Martins, Universidade de São Paulo, Faculdade de Ciências Farmacêuticas, São Paulo, Brazil; L. T. Kubota, Universidade Estadual de Campinas, Instituto de Química, São Paulo, Brazil

ABSTRACT: New polymeric electrode responding to furosemide was constructed by incorporating the Furosemide–Aliquat ion pair complex into a poly(vinyl chloride) (PVC) membrane. The electrode exhibited a linear response over the concentration range 1.59 × 10⁻⁴–1.00 × 10⁻² mol L⁻¹, a detection limit of 1.19 × 10⁻⁴ mol L⁻¹ with E = −245.6–58.9log[Fur]. The pH did not affect the response of the electrode within the range 7–10. Direct potentiometry was used to assay furosemide in pharmaceutical preparations. The results were compared with those obtained with spectrophotometric and chromatographic reference methods.

Analytical Letters, 37(1), 35–46 (2004)

Abstract

VOLTAMMETRIC BEHAVIOR OF INDINAVIR AND DETERMINATION IN PHARMACEUTICAL DOSAGE FORMS by Nevin Erk, Ankara University, Faculty of Pharmacy, Department of Analytical Chemistry, 06100 Ankara, Turkey

ABSTRACT: The oxidative behavior of indinavir has been investigated by cyclic, linear sweep, differential pulse and square‐wave voltammetry using a glassy carbon electrode in different buffer systems. Cyclic voltammetry was used to study the influence of pH on the peak current and peak potential. The solution conditions and instrumental parameters were optimized to obtain a good sensitivity. The Britton–Robinson buffer of pH 6.0 was selected as a suitable analytical medium in which indinavir exhibited a sensitive diffusion controlled oxidative peak at +892.0 mV (vs. Ag/AgCl). The oxidation process was shown to be irreversible. The peak current varied linearly with drug concentration in the range between 2.8 × 10⁻⁷ and 5.0 × 10⁻⁵ M. The proposed voltammetric techniques have been applied to the determination of the drug in pharmaceutical dosage forms with good recoveries. For comparative purposes a HPLC with a diode array and multiple wavelength UV/VIS detection determination also was developed.

Analytical Letters, 37(1), 47–63 (2004)

Abstract

VOLTAMMETRIC BEHAVIOR AND DETERMINATION BY FLOW INJECTION WITH AMPEROMETRIC DETECTION OF BENZIMIDAZOLES by A. Guzmán‐Vázquez de Prada, M. L. Mena, A. J. Reviejo, and J. M. Pingarrón, Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, 28040‐Madrid, Spain

ABSTRACT: The voltammetric behavior of fenbendazole, albendazole, thiabendazole, and mebendazole at a glassy carbon electrode in different aqueous (Britton–Robinson buffer, KOH solutions) and predominantly nonaqueous (acetonitrile:water and methanol:water mixtures) working media is reported. 0.1 M KOH and 70:30 acetonitrile or methanol:water mixtures were selected as most appropriate, the sensitivity achieved for the square wave voltammetric determination of fenbendazole in 0.1 M KOH being much higher than in the predominantly nonaqueous media. Flow‐injection with amperometric detection of the benzimidazoles was evaluated in the three working media. The electrode responded rapidly and the response was constant over sets of 30 measurements at the selected potentials in all cases, RSD values ranging between 1.6% and 4.4%. No significant electrode surface fouling was observed under the hydrodynamic conditions. Detection limits in the 1.0 × 10⁻⁸–1.0 × 10⁻⁷ M concentration range were achieved. As an application, fenbendazole was determined by flow injection with amperometric detection in spiked feed samples at the 30 and 180 µg g⁻¹ concentration levels, which correspond to the lower and upper concentration for fenbendazole administration to treated poultry. Recoveries of 97% ± 5% and 94% ± 8% were obtained.

Analytical Letters, 37(1), 65–79 (2004)

Abstract

RP‐HPLC ASSAY OF ROFECOXIB FROM PHARMACEUTICAL DOSAGE FORMS AND HUMAN PLASMA AND ITS DRUG DISSOLUTION STUDIES by A. Savaşer, Y. Özkan, C. K. Özkan, and Ç. Taş, Gülhane Military Medical Academy, Department of Pharmaceutical Technology, 06018, Ankara, Turkey; S. A. Özkan, Ankara University, Faculty of Pharmacy, Department of Analytical Chemistry, 06100, Ankara, Turkey

ABSTRACT: A high performance liquid chromatographic (HPLC) method is described for the determination of rofecoxib (RFC) in bulk drug, tablets and human plasma samples. The methods are linear over the concentration ranges 0.005–30.0 and 0.010–10 µg mL⁻¹ in mobile phase and human plasma, respectively. Chromatography was carried out on a reversed phase Spherisorb ODSI column using a mixture of acetonitrile:methanol:0.067 M KH₂PO₄ (27:20:53; v/v/v) adjusted to pH 6.95 with 3 M NaOH. Detection was realized at 244 nm using a DAD detector. The retention time observed for RFC and etodolac (internal standard) at about 7.5 and 10.7 min, respectively. The proposed RP‐HPLC method was validated for precision, accuracy, ruggedness and recovery. The limit of detection was found to be 0.00143 and 0.00301 µg mL⁻¹ in mobile phase and human plasma samples, respectively. The proposed method allows a number of cost and time saving benefits. The described method can be readily applied for the analysis of tablets, drug dissolution studies and human plasma samples. This method could be used without any interference from tablet matrix and endogenous substance from the plasma samples.

Analytical Letters, 37(1), 81–97 (2004)

Abstract

PESTICIDE RESIDUE ANALYSIS IN WATERS BY SOLID‐PHASE MICROEXTRACTION COUPLED TO GAS CHROMATOGRAPHY‐TANDEM MASS SPECTROMETRY by F. J. Arrebola, A. Garrido Frenich, and J. L. Martínez Vidal, Department of Analytical Chemistry, Faculty of Experimental Sciences, University of Almería, 04071 Almería, Spain; S. Cortes Aguado and N. Sánchez‐Morito, Pesticide Residue Laboratory C.U.A.M. Paraje “El Treinta,” 5; 04700 El Ejido, Almería, Spain

ABSTRACT: A new analytical method is proposed for determining 34 multi‐class pesticides in drinking and natural (ground, surface and sea) waters. The method combines the advantages of solid‐phase microextraction (SPME) and gas chromatography‐tandem mass spectrometry (GC‐MS‐MS). Polydimethylsiloxane (PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) stationary phases were evaluated and the optimization of the main extraction parameters was carried out in order to improve sensitivity and selectivity. That is the case of the influence of agitation, adsorption and desorption times, desorption temperature, addition of electrolytes, and pH of the sample. Performance characteristics of the analytical method were evaluated in order to validate the proposed methodology. Quantification limits were lower than 35.5 ng L⁻¹ in all cases and therefore, the method can be applied for determining the target pesticides in drinking waters at concentrations below the levels allowed by EU and US legislation (100 ng L⁻¹). The calibration was performed between 50 and 500 ng L⁻¹ using linear or polynomial mathematical functions. Recovery rates (between 80.7% and 110.0% in all cases), and precision (<15.2% in all cases, expressed as relative standard deviation) were studied too. The method was applied to the analysis of natural and drinking water samples from the South‐East of Spain, an intensive agricultural area. Pesticides most detected were endosulfan and lindane at concentrations that, in general, were lower than 100 ng L⁻¹.

Analytical Letters, 37(1), 99–117 (2004)

Abstract

APPLICATION OF RAMAN SPECTROSCOPY TO DISTINGUISH METAMORPHIC AND IGNEOUS ZIRCONS by W. S. Xian, M. Sun, J. Malpas, G. C. Zhao, and M. F. Zhou, Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., P.R. China; K. Ye and J. B. Liu, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, P.R. China; D. L. Philips, Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., P.R. China

ABSTRACT: Raman spectroscopy is used for the first time for distinguishing igneous zircons from metamorphic zircons. Igneous zircons, especially those from granitic rocks, commonly show a Raman peak at 1461 Δcm⁻¹ with significant intensity, whereas metamorphic zircons do not show this peak or the peak is very weak. This may be related to the rare‐earth‐element contents in zircon. Thus, Raman spectroscopy provides a new, fast and non‐destructive means for investigating the structure and origin of zircons.

Analytical Letters, 37(1), 119–130 (2004)

Abstract

POST‐CHROMATOGRAPHIC DETECTION OF PROGESTERONE USING TERBIUM‐SENSITIZED LUMINESCENCE by S. Rabouan and E. Barron, Laboratoire de Chimie Analytique, UFR Médecine et Pharmacie, BP 199, 86005 Poitiers Cedex, France; B. Legube, Laboratoire de Chimie de l'Eau et de l'Environnement, UMR CNRS 6008, Ecole Supérieure d'Ingénieurs de Poitiers, 40, Ave. du Recteur Pineau, 86022 Poitiers Cedex, France

ABSTRACT: This report deals with a time‐resolved fluorometric determination of progesterone by reversed‐phase high‐performance liquid chromatography. The method was simple to use and performed on a C18 column, with acetonitrile/water 80:20 as mobile phase (flushed at 1 mL min⁻¹), and a 0.03 mol L⁻¹ Tb(NO₃)₃, 0.005 mol L⁻¹ SDS methanolic miscellaneaous solution as post‐column reagent (added at 0.8 mL min⁻¹). The validation of the assay was performed for a 200‐µL injection, and it showed that this method presented no interferences with estrogens, and that it was linear in the range 5 × 10⁻⁶–75 × 10⁻⁶ mol L⁻¹ (correlation coefficient of 0.99), repeatable (3.7% intra‐day RSD and 5.6% inter‐day RSD, at 40 × 10⁻⁶ mol L⁻¹), with a detection limit at 2.5 × 10⁻⁶ mol L⁻¹, and a quantification limit at 5 × 10⁻⁶ mol L⁻¹.

Analytical Letters, 37(1), 131–142 (2004)

Abstract

FLOW‐INJECTION CHEMILUMINESCENCE DETERMINATION OF PAPAVERINE USING CERIUM(IV)-SULFITE SYSTEM by S. Zhang, Y. Zhuang, and H. Ju, Department of Chemistry, Institute of Analytical Science, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P.R. China

ABSTRACT: A sensitizing effect of papaverine on the weak chemiluminescence (CL) reaction of sulfite with acidic cerium(IV) is studied. In papaverine and cerium(IV) solution, the increase in the fluorescent intensity of cerium(III) at 360 nm with an increasing time indicates a slow oxidation of papaverine by acidic cerium(IV). This reaction results in the formation of intermediate radical of papaverine, which enhanced the CL emission of sulfite–cerium(IV) system. Based on this finding, a flow injection (CL) method is proposed for the determination of papaverine. The CL intensity is proportional to the concentration of papaverine from 1.0 × 10⁻⁷ to 1.0 × 10⁻⁵ M with a correlation coefficient of 0.9991. The detection limit is 8.7 × 10⁻⁸ M (3σ). The relative standard deviation for seven independent determinations of 1.0 × 10⁻⁶ M papaverine is 2.0%. The proposed method has been satisfactorily used for the determination of papaverine in pharmaceutical preparations and biological fluids.

Analytical Letters, 37(1), 143–155 (2004)

Abstract

ANALYSIS OF MIXTURE OF CATCHINS, FLAVONES, FLAVANONES, FLAVONOLS, AND ANTHOCYANIDINS BY RP‐HPLC by R. Baranowski, J. Kabut, and I. Baranowska, Department of Analytical and General Chemistry, Silesian Technical University, 44‐100 Gliwice, M. Strzody 7, Poland

ABSTRACT: A reversed‐phase high performance liquid chromatographic (RP‐HPLC) separation system with diode array detector (DAD) was used to determine and quantify 21 flavonoids as aglycones and glycosides from five major flavonoid types (anthocyanidins, flavonols, flavanones, flavones, and catechins). The flavonoids were determined in freeze‐dried samples of fruit and vegetables. Identification of particular flavonoids in real samples was carried out by standard addition method and by comparing absorption spectra.

Analytical Letters, 37(1), 157–165 (2004)

Abstract

HPLC SEPARATION OF METALAXYL AND METALAXYL INTERMEDIATE ENANTIOMERS ON CELLULOSE‐BASED SORBENT by Z. Zhou, J. Qiu, X. Yang, and S. Jiang, Department of Applied Chemistry, China Agricultural University, Beijing 100094, China

ABSTRACT: A chiral stationary phase (CSP) was prepared by coating cellulose‐tris(3,5‐dimethyl‐phenylcarbamate) (CDMPC) onto aminopropylated spherical gel, and used this CSP to separate the enantiomers of metalaxyl and metalaxyl intermediate successfully by HPLC. The effects of 2‐propanol concentration in mobile phase on retention and resolution were investigated, and according to this an analytical method of the optical purity of metalaxyl and metalaxyl intermediate was established.

Analytical Letters, 37(1), 167–173 (2004)