Abstracts

Abstract

ANALYTICAL TECHNIQUES FOR ECSTASY by Deirdre Butler and George G. Guilbault, Chemistry Department, University College Cork, Cork, Ireland

ABSTRACT: In this mini review, first, a comprehensive discussion of the background chemistry, metabolism, pharmacology, toxicology, effects on humans, diagnosis, and treatment is introduced, followed by a detailed listing of current chemical and bioanalytical methods, the immunochemical techniques, and commercially available kits. An attempt has been made to introduce the reader to the broad area of drugs of abuse, such as with Ecstasy, and the current status of analytical methodology.

Analytical Letters, 37(10), 2003–2030, 2004

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VOLTAMMETRIC BEHAVIOR OF DOBUTAMINE AT POLY(ACRIDINE ORANGE) FILM MODIFIED ELECTRODE AND ITS DETERMINATION BY ADSORPTIVE STRIPPING VOLTAMMETRY by Yan Zhang, Pingdingshan Institute of Technology, Pingdingshan 467000, P.R. China

ABSTRACT: Acridine orange was electropolymerized on a glassy carbon electrode by using a potentiodynamic technique to construct a catalytic interface for the investigation of dobutamine (DBTM). The electrochemical behaviors of DBTM on the modified electrode were studied by determining the influences from solution acidity, the scan rate, the accumulation time, and the working temperature. Experiments showed that two oxidation peaks (P₁ and P₂) and one reduction peak (P₃) appeared for DBTM on the poly(acridine orange) film (PAO) modified electrode. The peak current of P₁ exhibits a linear relationship with the variation of DBTM concentration in a wide concentration range (5.0 × 10⁻⁸ to 1.0 × 10⁻⁴ M). Under the optimum conditions, the detection limit has been estimated as 2.0 × 10⁻⁹ M with 200 sec open circuit accumulation. This method has been used successfully for the detection of DBTM in injections due to its good reproducibility and simplicity.

Analytical Letters, 37(10), 2031–2042, 2004

Abstract

MOLECULARLY IMPRINTED POLYMERS WITH p‐ACETAMINOPHENOL AND ITS POSITIONAL ISOMERS AS TEMPLATES by Min Li Yang and Yuan Zong Li, The Key Laboratory of Bioorganic and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 1000871, P.R. China

ABSTRACT: In this study, molecularly imprinted polymers (MIP) with p‐acetaminophenol (p‐AMP) and its positional isomers as templates were synthesized. Several structural analogues, phenol, acetanilide (AN), p‐nitrophenol, (p‐NP) and p‐aminophenol (p‐AP) were chosen to study the selectivity of the MIPs in different mobile phases. In addition, the separation of the positional isomers was also investigated. The experimental results showed that, in the mobile phase with less polarity, the retention of the compounds was increased greatly on both blank polymer and the MIPs, thus leading no enhancement in the imprinting effect and selectivity. In addition, the use of dichloromethane/acetonitrile as the mobile phase favors the separation of the positional isomers, and baseline separation can be achieved only on the column based on the polymer imprinted with m‐acetaminophenol (m‐AMP) as a template.

Analytical Letters, 37(10), 2043–2052, 2004

Abstract

SINGLE‐CELL ANALYSIS IN A PLASTIC MICROFLUIDIC CHANNEL WITH A HADAMARD TRANSFORM MICROSCOPIC FLUORESCENCE IMAGE SYSTEM by Tao Li, Hongwu Tang, Meina Luo, and Guanquan Chen, Center of Analysis and Measurement, College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072, P.R. China

ABSTRACT: In this report, a single‐channel chip fabricated with polymethylmethacrylate (PMMA) material was applied to sampling single pollen cells stained with acridine orange (AO). A home‐made Hadamard transform (HT) microscopic fluorescence image system was used to detect the fluorescence signal emitted from the cells and obtain 511 × 512‐pixel two‐dimensional image of single cells, by which single‐cell fluorescence was measured accurately and the DNA content was determined quantitatively. The single‐cell sampling and the on‐line imaging were discussed in detail. The PMMA chip, with a suitable channel approximately 100 µm in depth and 108 µm in width, was proved suitable for single‐cell sampling. The HT instrument was well matched to the on‐line imaging due to the powerful resolving ability. The reliability of the measurement was evaluated by measuring the fluorescent intensity of AO‐stained pollens in the channel for 11 times, with a coefficient of variation (CV) of 2.78%. The method was used for quantitative measurements of DNA contents in two kinds of pollens with satisfactory results, which show that the method is rapid, accurate, and reliable in single‐cell analysis.

Analytical Letters, 37(10), 2053–2065, 2004

Abstract

TIME‐RESOLVED LUMINESCENCE SCREENING ASSAY FOR TETRACYCLINES IN CHICKEN MUSCLE by Marilyn J. Schneider and Guoying Chen, Eastern Regional Research Center, Agricultural Research Service US Department of Agriculture 600 E. Mermaid Lane, Wyndmoor, Pennsylvania, USA

ABSTRACT: A time‐resolved luminescence (TRL) assay was developed for effective screening of tetracyclines in chicken muscle at the E.U. maximum residue level of 100 ng g⁻¹. The method involves extraction of the tetracyclines with McIlvaine–ethylenediamine tetraacetic acid (EDTA) buffer, centrifugation, solid‐phase extraction (SPE) clean‐up, formation of an Eu(III) complex, and then measurement of the TRL signal at 615 nm (excitation at 388 nm). Samples fortified with tetracycline (TC), oxytetracycline (OTC) or chlortetracycline (CTC) gave a linear response over the range of 0–1000 ng g⁻¹, with relative sensitivities 5.4×, 2.4×, and 1×, respectively. Limits of detection for TC, OTC, and CTC were 3.5, 8, and 19 ng g⁻¹, respectively. Examination of the least sensitive case, CTC, showed no overlap between the TRL of control chicken extracts and those that had been fortified with 100 ng g⁻¹ CTC. The within‐day variation for these samples averaged 3.1% RSD, as did the day‐to‐day variation. The method was tested with blind control and fortified samples over the range of 20–500 ng g⁻¹ CTC to illustrate its utility. Other veterinary drugs approved for chickens in US (enrofloxacin, nicarbazin, tylosin) did not interfere. This method can provide a useful alternative to microbial screening assays for tetracyclines.

Analytical Letters, 37(10), 2067–2078, 2004

Abstract

DIFFERENTIAL PULSE ADSORPTIVE STRIPPING VOLTAMMETRIC DETERMINATION OF NIFEDIPINE AND NIMODIPINE IN PHARMACEUTICAL FORMULATIONS, URINE, AND SERUM SAMPLES BY USING A CLAY‐MODIFIED CARBON‐PASTE ELECTRODE by T. Madhusudana Reddy and S. Jayarama Reddy, Department of Chemistry, Electrochemical Research Laboratories, Sri Venkateswara University, Tirupati, India

ABSTRACT: A simple, rapid, and selective differential pulse adsorptive stripping voltammetric (DPAdSV) method has been developed for the determination of nifedipine and nimodipine based on reduction of an aromatic nitro group in the drugs at a bare carbon‐paste electrode (CPE) and a clay‐modified carbon‐paste electrode (CMCPE). Compared with a bare CPE, CMCPE gave the highest sensitivity in the present developed method. The analytical parameters that affect the electrode reaction process have been studied in terms of pH of the supporting electrolyte, accumulation time, accumulation potential, and composition of a modifier on the adsorptive stripping response by using differential pulse voltammetry. When CMCPE was used, the peak current vs. concentration relationship was found to be linear over the range 4.6 × 10⁻¹⁰–2 × 10⁻⁷ M and 5.4 × 10⁻¹⁰–4 × 10⁻⁷ M, with a limit of detection (LOD) 3.9 × 10⁻¹⁰ and 4.8 × 10⁻¹⁰ M, and correlation coefficient of 0.9996 and 0.9998 for nifedipine and nimodipine, respectively. The method was applied successfully for the direct determination of nifedipine and nimodipine in tablet dosage forms, urine, and serum samples.

Analytical Letters, 37(10), 2079–2098, 2004

Abstract

FLOW‐INJECTION SPECTROPHOTOMETRIC DETERMINATION OF AMOXCILLIN, CEPHALEXIN, AMPICILLIN, AND CEPHRADINE IN PHARMACEUTICAL FORMULATIONS by I. F. Al‐Momani, Chemistry Department, Yarmouk University, Irbid, Jordan

ABSTRACT: Amoxcillin, cephalexin, ampicillin, and cephradine were determined spectrophotometrically in the pure form and in the pharmaceutical formulations by using flow‐injection analysis (FIA). The method is based upon the hydrolysis of the drug under investigation in basic medium and then the reduction of the formed hydrolyzed product by the on‐line generated I₂ in acidic medium. The decrease in the intensity of the I₂ color was monitored at 460 nm and found to be proportional to the concentration of the compound under investigation. Variables such as acidity, reagent concentrations, flow rate of reagents, and other FI parameters were optimized to produce the most sensitive and reproducible results. The method was successfully applied to the analysis of pharmaceutical preparations.

Analytical Letters, 37(10), 2099–2110, 2004

Abstract

FLOW INJECTION SPECTROPHOTOMETRIC DETERMINATION OF ISOPROTERENOL WITH AN ON‐LINE SOLID‐PHASE REACTOR CONTAINING IMMOBILIZED MANGANESE DIOXIDE by Viviane G. Bonifácio, Luiz H. Marcolino‐Júnior, and Orlando Fatibello‐Filho, Departamento de Química, Centro de Ciências Exatas e de Tecnologia, Universidade Federal de São Carlos, São Carlos, SP, Brazil

ABSTRACT: This work reports the application of a simple, sensitive, and rapid flow injection system for the spectrophotometric determination of isoproterenol by using a solid‐phase reactor containing MnO₂(s) immobilized in a polyester resin. The method is based on the oxidation of isoproterenol to produce isoproterochrome, which was monitored at 492 nm. The analytical curve was linear in the isoproterenol concentration range from 1.0 × 10⁻⁵–2.0 × 10⁻⁴ mol L⁻¹, with a detection limit of 1.7 × 10⁻⁶ mol L⁻¹. The relative standard deviation (RSD) was 0.9%, and an analytical frequency of 60 hr⁻¹ was obtained. The average recoveries varied from 101.0% to 104.2%, evidencing the absence of matrix effect on the flow injection procedure. The effect of excipient substances frequently found with isoproterenol in pharmaceutical formulations, such as lactose, sucrose, starch, poly(ethylene glycol), and sodium chlorine was evaluated by using the proposed flow procedure. None of these substances caused significant interference in the proposed method. The procedure was successfully applied to the determination of isoproterenol in pharmaceutical preparations, and the results were compared with those results obtained by using an ultraviolet (UV)‐spectrophotometric method.

Analytical Letters, 37(10), 2111–2123, 2004

Abstract

LIQUID CHROMATOGRAPHIC AND SPECTROPHOTOMETRIC DETERMINATION OF PHENAZOPYRIDINE HYDROCHLORIDE, AMPICILLINE TRIHYDRATE, AND NITROFURANTOINE IN PHARMACEUTICAL PREPARATIONS by İ. M. Palabıyık and F. Onur, Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Tandoğan, Ankara, Turkey

ABSTRACT: The present work describes two new liquid chromatographic (LC) methods and three new spectrophotometric methods for the simultaneous determination of phenazopyridine hydrochloride (PHEN), ampicilline trihydrate (AMP), and nitrofurantoine (NIT) in their binary combinations. In the LC methods, a Nucleosil C8 column with a mobile phase composed of methanol–acetonitril–water (42:42:16, v/v/v) with ultraviolet (UV) detection at 260 nm was used for a PHEN–NIT combination and a Nucleosil C8 column with a mobile phase composed of methanol–water (80:20, v/v) with UV detection at 260 nm was used for the PHEN–AMP combination. For spectrophotometric methods, a ratio spectra derivative spectrophotometric and two chemometric methods in spectrophotometry were used. In ratio spectra derivative spectrophotometric methods, analytical signals were measured at the wavelengths corresponding to either maximums and minimums for these drugs in the second derivative spectra of the ratio spectra obtained by using every other zero‐order spectra as the divisor in their solution in methanol–0.1 M HCl (1:1) for PHEN–NIT and PHEN–AMP mixtures in the 200–300 nm range. Principal component regression (PCR) and partial least‐squares (PLS‐1) methods were used as chemometric techniques. In these techniques, the concentration data matrix was prepared by using the synthetic mixtures containing these drugs in methanol–0.1 M HCl (1:1). The absorbance data matrix corresponding to the concentration data matrix was obtained by the measurements of absorbances at more than 14 wavelengths in the range 200–300 nm, at appropriate Δλ in the zero‐order spectra in both techniques for these two binary combinations. The spectrophotometric procedures do not require any separation step. The accuracy, precision, and the linearity ranges of the methods have been determined, and they have been validated by analyzing synthetic mixtures containing the title drugs. These four methods were successfully applied to the pharmaceutical formulations, capsule, and tablet, and the results were compared with each other.

Analytical Letters, 37(10), 2125–2150, 2004

Abstract

RAPID ANALYSIS OF THE VOLATILE COMPOUNDS IN THE RHIZOMES OF RHODIOLA SACHALINENSIS AND RHODIOLA SACRA BY STATIC HEADSPACE‐GAS CHROMATOGRAPHY–TANDEM MASS SPECTROMETRY by Hao‐Yang Wang and Yin‐Long Guo, Shanghai Center of Mass Spectrometer, Shanghai Institute of Organic Chemistry, The Chinese Academy of Sciences, Shanghai, China

ABSTRACT: A rapid static headspace‐gas chromatography–mass spectrometry (GC–MS) method was used to determine and to identify the volatile compounds in the rhizomes of Rhodiola sachalinensis and Rhodiola sacra. The total ion chromatograms (TIC) of the rhizomes powders of the R. sachalinensis and R. sacra showed their differences in the volatiles compositions. Thirty‐two volatile compounds in the rhizome of R. sachalinensis were identified; the main volatile compounds are butanal, 2,6,6‐trimethyl‐2‐ethenyltetrahydro‐2‐pyran, limonene, linalool, geranial, 2‐butanal, and 3‐butanal. Twenty five volatile compounds in the rhizome of R. sacra were identified with butanal, 3‐butanal, 2‐butanal, β‐pinene, limonene, terpinolene, and linalool. 2,6,6‐Trimethyl‐2‐ethenyltetrahydro‐2‐pyran was further identified by the MS–MS technique. The applied method not only effectively differentiates the two species of Rhodiolas but also offers a prospective method for the quality control of aromatic medicine plants.

Analytical Letters, 37(10), 2151–2161, 2004

Abstract

FLOW‐INJECTION ANALYSIS SPECTROPHOTOMETRIC DETERMINATION OF BISMUTH IN ENVIRONMENTAL AND PHARMACEUTICAL SAMPLES by Kavita Agrawal, Girdhari Lal Mundhara, and Khageshwar Singh Patel, School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur 492010CG, India and Peter Hoffmann, Analytical Chemistry, Material Science, Technical University, Petersenstr, Darmstadt, Germany

ABSTRACT: A new, simple, rapid, selective, and sensitive flow‐injection analysis (FIA) method for the spectrophotometric determination of Bi is described. It is based on reaction of Bi (III) with I⁻ ions in the presence of cationic surfactants (CS), i.e., cetylpyridinium chloride, cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, dodecyltrimethylammonium bromide in sulfuric media to give a violet‐colored complex. The apparent value of molar absorpitivity of the complex in the terms of Bi with four CSs lie in the range of (1.00–1.20) × 10⁴ L mol⁻¹ cm⁻¹ at λ_max 490 nm. Among them, the most sensitive CSs, i.e., cetylpyridinium chloride (CPC) has been selected for the detailed studies. The detection limit (causing absorbance >3 sec) of the method is 65 µg L⁻¹ Bi. The sample throughput of the method is >120 samples hr⁻¹. The effect of diverse ions and surfactants in the FIA determination of Bi is examined. The composition of the complex is discussed. The analytical and FIA variables in the determination of Bi are optimized. The method has been applied for analysis of Bi in the environmental and pharmaceutical materials.

Analytical Letters, 37(10), 2163–2174, 2004

Abstract

SPECTROFLUORIMETRIC DETERMINATION OF CERTAIN FLUOROQUINOLONE THROUGH CHARGE TRANSFER COMPLEX FORMATION by Liming Du, Aiping Lin, and Yaqin Yang, Analytical and Testing Center, Shanxi Normal University, Shanxi Linfen, P.R. China

ABSTRACT: A highly sensitive spectrofluorimetric method was developed for the analysis of four fluoroquinolones (FQs) antibacterials, namely norfloxain (NOR), lomefloxacin (LOM), pefloxacin (PEF), and levofloxacin (LEV), in their pharmaceutical dosage forms or in biological fluids through charge transfer (CT) complex formation with tetracyanoethylene (TCNE). The TCNE was found to react with these drugs to produce stable complexes, and the fluorescence intensity of the complexes was greatly enhanced. The formation of such complexes was also confirmed by infrared measurements. Optimum conditions for the formation of CT complexes have been investigated. Under optimum conditions, the detection limits were 1.0, 0.6, 0.8, and 0.4 ng mL⁻¹ for NOR, LOM, PEF, and LEV, respectively, while the range of application was 2.0–900 ng mL⁻¹ for all four drugs. The method has been successfully applied to determine their pharmaceutical dosage forms with good precision and accuracy. They were also applied for the determination of studied drugs in human urine samples.

Analytical Letters, 37(10), 2175–2187, 2004

Abstract

THE USE OF ALGAE CHLORELLA VULGARIS IMMOBILIZED ON CELLEX‐T SUPPORT FOR SEPARATION/PRECONCENTRATION OF TRACE AMOUNTS OF PLATINUM AND PALLADIUM BEFORE GFAAS DETERMINATION by Urszula Dziwulska and Beata Godlewska‐Żyłkiewicz, Institute of Chemistry, University of BiałystokHurtowa 115‐399, Białystok, Poland and Andrzej Bajguz, Institute of Biology, University of Białystok, Białystok, Poland

ABSTRACT: The ability of green algae Chlorella vulgaris, immobilized on Cellex‐T support, for selective binding of platinum (Pt) and palladium (Pd) from acidic solutions (at pH range 1.5–1.8) has been demonstrated. The use of immobilized algae packed into a microcolumn (150 mg) in a flow mode provides good efficiency and reproducibility of the biosorption process (95.2 ± 0.4% for Pt and 99.3 ± 0.9% for Pd). The presence of seven interfering ions up to their 100 µg mL⁻¹ concentration does not influence Pt and Pd retention on the column. The best efficiency of elution for both metals from the column was obtained with 0.3 mol L⁻¹ thiourea (TU) etc in 1 mol L⁻¹ hydrochloric acid used as a stripping reagent The detection limits obtained by the optimized method, followed by graphite furnace atomic absorption spectrometric detection for Pt and Pd, were 0.2 and 0.096 ng mL⁻¹, respectively. The proposed method was applied for matrix separation and determination of Pt and Pd by graphite furnace atomic absorption spectrometry (GFAAS) in spiked tap water, wastewater, and grass samples.

Analytical Letters, 37(10), 2189–2203, 2004

Abstract

KINETIC SPECTROPHOTOMETRIC DETERMINATION OF NITRITE BASED ON ITS CATALYTIC EFFECT ON THE OXIDATION OF METHYL RED BY BROMATE by J. Ghasemi, A. G. Oskoei, and B. Abdolahi, Department of Chemistry, Faculty of Sciences, Razi University, Kermanshah, Iran; A. Jabbari, Department of Chemistry, Faculty of Sciences, K. N. Toosi University of Technology, Tehran, Iran; and A. Amini, Department of Biology, Faculty of Sciences, Razi University, Kermanshah, Iran

ABSTRACT: A precise, sensitive, and accurate catalytic spectrophotometric method for the determination of nitrite in food stuff is presented. In acidic solution, methyl red (MR) is oxidized by bromate to form a colorless compound. The reaction is accelerated by trace amounts of nitrite and can be followed by measuring the absorbance at 520 nm. The absorbance of the reaction mixture decreases with increasing time and reaches to a minimum that is inversely related to the nitrite concentration. The change in absorbance at 25 and 50 sec was calculated as an analytical signal. Under the optimum experimental conditions (0.3 M sulfuric acid, 1.1 × 10⁻⁵ M MR, 2.6 × 10⁻⁴ M bromate, 0.2 M nitrate, and 25°C), nitrite can be determined in the range of 0.05–1.2 µg g⁻¹. The standard deviation is 0.06 for six replications at 0.3 µg g⁻¹.The detection limit as the mean of the blank signals plus three times the blank standard deviation is 0.045 mg kg⁻¹. The method was successfully applied for the determination of nitrite in meat products.

Analytical Letters, 37(10), 2205–2214, 2004