Abstracts

Abstract

DETERMINATION OF ISOPEROXISOMICINE A1 CONTENT IN PEROXISOMICINE A1 BATCHES BY MEANS OF ¹H NMR by Adrián Fernández‐Ramírez, Ma de la Luz Salazar‐Cavazos, Verónica Rivas‐Galindo, Lucía Ceniceros‐Almaguer, and Noemí Waksman de Torres, Department of Analytical Chemistry, Faculty of Medicine, U.A.N.L. P.O. Box 2316, Sucursal Tecnológico 64841 Monterrey, N.L., México

ABSTRACT: Peroxisomicine A1 (PA1) is a natural product that shows biological activity. After its extraction and isolation from the plant, there is still between 3 and 5% remaining of an isomer (isoperoxisomicine A1, isoPA1), which is also present in the original matrix. A simple and reliable quantification method has been developed by means of proton nuclear magnetic resonance spectroscopy to determine the isoperoxisomicine amount in these PA1 batches. Two methods were applied to the quantification: the relative area method and an absolute method by using an internal standard. No significant differences were found between them. The simplicity of the first one makes it desirable for routine analysis. The validated method has adequate linearity and precision, because it allows measuring as low as 1% of isoPA1 content.

Analytical Letters, 37(12), 2433–2444, 2004

Abstract

DETERMINATION OF CATECHOLAMINES BY FLOW INJECTION CHEMILUMINESCENCE METHOD BASED ON THEIR RESTRAINING EFFECTS ON THE LUMINOL–POTASSIUM CHLORATE SYSTEM by Yuanyuan Sun, Yuhai Tang, Xiaohui Zheng, Hong Yao, and Zhao Xu, Department of Chemistry, College of Science, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China

ABSTRACT: A rapid and precise continuous flow method was described for the determination of catecholamines based on the catecholamines great inhibitory effects on the chemiluminescence reaction of luminol–potassium chlorate in basic solutions. The optimum chemical conditions for the chemiluminescence reaction were investigated. Under the optimized conditions, four catecholamines: adrenaline, noradrenaline, isoprenaline, and dopamine were determined. The detection limits are 0.2 ng mL⁻¹ for adrenaline, 0.4 ng mL⁻¹ for noradrenaline, 0.7 ng mL⁻¹ for isoprenaline, and 0.4 ng mL⁻¹ for dopamine. The method was successfully applied to the determination of the four catecholamines in pharmaceutical injections. A brief discussion on the possible chemiluminescence reaction mechanism is presented.

Analytical Letters, 37(12), 2445–2458, 2004

Abstract

DETERMINATION OF TRACE VANADIUM(V) BY SOLID SUBSTRATE ROOM TEMPERATURE PHOSPHORIMETRY BASED ON THE CATALYZED REACTION OF POTASSIUM BROMATE OXIDIZING SAFRANINE O ACTIVATED BY VITAMIN C by Jia‐Ming Liu, Tian‐long Yang, Hai‐bo Wu, Qiao‐mei Lu, and Ai‐Hong Wu, Department of Chemistry, ZhangZhou Normal College, ZhangZhou 363000, P.R. China; and Long‐Di Li, Department of Chemistry, Tsinghua University, Beijing, P.R. China

ABSTRACT: A new method for the determination of trace vanadium(V) by solid substrate room temperature phosphorimetry (SS‐RTP) has been established. It is based on the facts that in the presence of sulfuric acid and sodium dodecyl benzene sulfonate (DBS), vanadium activated by vitamin C (Vc) can catalyze potassium bromate to oxidize safranine O (R), the oxidation products of safranine O can emit intense and stable solid substrate room temperature phosphorescence (SS‐RTP) on nitrocellulose membrane. The catalytic reaction is a first‐order reaction, with a reaction rate constant (k) of 7.3 × 10⁻⁴ sec⁻¹, and the apparent activation energy (E) is 46.09 kJ/mol. The phosphorescence intensity (ΔI _p) will be increased 10 times if Vc is added. The linear range of this method is 1.6–16.0 fg/spot within which ΔI _p obeyed Beer's Law, the detection limit (LD) is 0.38 fg/spot (0.4 µL sample solution per spot), and the regression equation for working curve is ΔI _p = 52.17 + 3.181m _V(V) (fg/spot), n = 6, correlation coefficient r is 0.9993. This sensitive method has been applied to the determination of trace vanadium in tea and human hair samples successfully. The mechanism of the catalytic reaction was also discussed.

Analytical Letters, 37(12), 2459–2467, 2004

Abstract

HIGHLY SENSITIVE SPECTROPHOTOMETRIC REACTION RATE METHOD FOR THE DETERMINATION OF SELENIUM BASED ON THE CATALYTIC REDUCTION OF SULFONAZO BY SULFIDE by Ali A. Ensafi and M. Saberi Lemraski, College of Chemistry, Isfahan University of Technology, Isfahan 84156, Iran

ABSTRACT: A sensitive and rapid kinetic spectrophotometric method was developed for the determination of ultratrace amounts of selenium [Se (VI), Se (IV), and total selenium]. The method is based on the catalytic effect of Se (IV) on the reduction of sulfonazo by sodium sulfide. The reaction was followed spectrophotometrically by measuring the decrease in absorbance at 570 nm for the reaction mixture or by measuring the increase in absorbance of the reaction mixture at 680 nm and at 25°C, by the fixed‐time method. Selenium could quantitatively be determined in the range of 0.5–180 and 50–2300 ng mL⁻¹ at 680 and 570 nm, respectively. The limit of detection is 0.3 ng mL⁻¹ Se (IV) at 680 nm. All of the variables that affect the sensitivity in the two wavelengths were investigated, and the optimum conditions were established. The interference effect of various cations and anions on the Se (IV) determination was also studied. The selectivity of the selenium determination was greatly improved with the use of the cation exchange resin. The method was used for the determination of Se (IV) in a food sample, natural water, and synthetic samples with satisfactory results.

Analytical Letters, 37(12), 2469–2483, 2004

Abstract

EXPERIMENTAL DESIGN TO INVESTIGATE FACTORS AFFECTING CAPILLARY ZONE ELECTROPHORESIS by C. V. Suresh Babu, Bong Chul Chung, and Young Sook Yoo, Bioanalysis and Biotransformation Research Center, Korea Institute of Science and Technology P.O. Box 131, Cheongryang, Seoul, Korea 130‐650 and C. V. Suresh Babu, International R&D Academy, Korea Institute of Science and Technology, Cheongryang, Seoul, Korea

ABSTRACT: An experimental design approach is described to evaluate the main electrophoretic parameters involved in neuropeptide separation by capillary zone electrophoresis coupled to ultraviolet detection. Response surface methodology based on a three‐level, three‐variable Box–Behnken design was used for optimization with respect to buffer pH, buffer concentration, and applied voltage. The optimum conditions of these variables were predicated by using a second‐order polynomial model fitted to the results obtained by applying the Box–Behnken design. The methodology identifies the principal experimental factors, which have significant effects in the separation. The optimum conditions were 100 mM phosphate buffer pH 2.5 as the background electrolyte and an applied voltage of 6 kV. Verification experiments were performed under optimal conditions, which yielded 98% of the predicated efficiency.

Analytical Letters, 37(12), 2485–2499, 2004

Abstract

AN ALTERNATIVE SAMPLE INTRODUCTION DEVICE FOR A HOME‐MADE CAPILLARY ELECTROPHORESIS SYSTEM by André F. Lavorante, Ana Paula G. Gervasio, Maria C. B. Moraes, and Maria F. Giné, Centro de Energia Nuclear na Agricultura CENA/USPAv. Centenário 30313416‐000, Piracicaba, SP, Brazil; Carlos E. S. Miranda and Emanuel Carrilho, Instituto de Química de São Carlos—IQSC/USP, São Carlos SP, Brazil; and Carlos E. S. Miranda, Universidade de Ribeirão Preto (UNAERP)Avenida Costábile Romano 220114096‐380, Ribeirão Preto SP, Brazil

ABSTRACT: A home‐made capillary electrophoresis (CE) system with an alternative interface for hydrodynamic injection of sample solutions is described. The interface is an acrylic chamber whose efficiency of injection was evaluated by the separation of cysteine and methionine standards. Important parameters inherent to this system such as peristaltic pump rotation, system grounding, and injection time were carefully investigated. Although this is a batch‐wise system, the interface showed a good efficiency for nano‐liter injections and relative standard deviations (RSD) smaller than 3% for both signal measurement and migration time were obtained. This new interface allowed a minimal capillary handling and also guaranteed an excellent performance in terms of sample solution injection into the home‐made system.

Analytical Letters, 37(12), 2501–2513, 2004

Abstract

A METHOD FOR NONEXTRACTIVE SIMULTANEOUS DETERMINATION OF THALLIUM (III) AND GALLIUM (III) IN ENVIRONMENTAL AND STANDARD SAMPLES WITH 2‐(5‐BROMO‐2‐PYRIDYLAZO)‐5‐DIETHYLAMINOPHENOL IN CATIONIC MICELLAR MEDIUM by S. Ratnani, S. K. Shukla, and G. K. Parashar, Department of Chemistry, University of Delhi, Delhi, India and N. K. Agnihotri, Motilal Nehru College, University of Delhi Benito Juarez Road, New Delhi 110021, India; and V. K. Singh, Sri Aurobindo College, New Delhi, India

ABSTRACT: A new sensitive and selective derivative spectrophotometric procedure is developed for trace‐level determination of Tl³⁺ in the range of 6.80 × 10⁻² to 3.80 µg mL⁻¹; molar absorption coefficient and detection limit of a 1:1 complex with 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol in the presence of cetylpyridinium chloride are 5.25 × 10⁴ L mol⁻¹ cm⁻¹ and 4.20 × 10⁻² ng mL⁻¹, respectively. The developed method, by using the measurement of the derivative amplitude of the analyte (Tl³⁺) at the zero crossover point of the interfering metal ion (Ga³⁺), is applied for the determination of Tl³⁺ in the presence of Ga³⁺, and vice versa for Ga³⁺ ions. The determination range of Tl³⁺ and Ga³⁺ in the presence of each other is 0.10–2.46 µg mL⁻¹ and 0.04–1.05 µg mL⁻¹, respectively; the relative standard deviation for sample containing 1.23 µg mL⁻¹ Tl³⁺ and 0.42 µg mL⁻¹ Ga³⁺ is 1.43 and 1.65%, respectively. The proposed procedure is successfully applied for simultaneous determination of the two metal ions in the environmental samples, standard reference materials, and synthetic binary mixtures.

Analytical Letters, 37(12), 2515–2529, 2004

Abstract

DETERMINATION OF PROPHAM AND CHLORPROPHAM IN POSTHARVEST‐TREATED POTATOES BY LIQUID CHROMATOGRAPHY WITH PEROXYOXALATE CHEMILUMINESCENCE DETECTION by Eva Orejuela and Manuel Silva, Department of Analytical Chemistry, Campus of Rabanales, University of Córdoba E‐14071, Córdoba, Spain

ABSTRACT: Determination of propham and chlorpropham in postharvest‐treated potato samples were examined using high‐performance liquid chromatography (HPLC) with chemiluminescence detection. After hydrolysis of the pesticides, aniline and 3‐chloroaniline metabolites were derivatized with dansyl chloride and the subsequent dansylated amines were injected into the chromatograph and detected by using an integrated chemiluminescence detection unit based on the bis(2,4,6‐trichlorophenyl) oxalate–hydrogen peroxide system. Conditions to obtain optimum derivatization and peroxyoxalate efficiencies were investigated. Dansylated metabolites were efficiently separated on a reversed‐phase C₁₈ column eluted with 60% aqueous acetonitrile solution at 0.8 mL min⁻¹ flow‐rate. The proposed method provided a very simple and sensitive procedure (limits of detection, 3.5 µg kg⁻¹) to determine propham and chlorpropham in potato samples. The ensuing method is a useful choice for the determination of these pesticides as it provides limits of detection lower than those reported by existing chromatographic alternatives without the use of an additional pre‐concentration technique. Application was illustrated by the determination of these pesticides in potato samples after a treatment with a commercial formulation.

Analytical Letters, 37(12), 2531–2543, 2004

Abstract

KINETIC SPECTROPHOTOMETRIC DETERMINATION OF FORMALDEHYDE IN FABRIC AND AIR BY SEQUENTIAL INJECTION ANALYSIS by Suling Feng, Xingguo Chen, and Zhide Hu, Department of Chemistry, Lanzhou University, Lanzhou 730000, P.R. China and Suling Feng, Jing Fan, and Aijun Wang, Key Laboratory of Environmental Science and Engineering of Henan Education Department and School of Chemical and Environmental Sciences, Henan Normal University, Xinxiang, China

ABSTRACT: A kinetic method for measuring formaldehyde by sequential injection analysis (STA) with spectrophotometric detection was developed for the first time. The method was based on the inhibitory effect of formaldehyde on the ethyl green (EG)–sulfite reaction. The linear range for formaldehyde was 1.0–20.0 µg mL⁻¹; the detection limit was 0.020 µg mL⁻¹. The measurement rate was 130 sec, thus allowing to analyze 27 samples per hour, the total reagent consumption in a cyclical procedure is only 240 µL. The method was applied to the determination of formaldehyde in fabric and air, and compared with acetyl acetone spectrophotometric method.

Analytical Letters, 37(12), 2545–2555, 2004

Abstract

DETERMINATION OF PURITY AND COMPONENTS IN DIMETHYL CARBONATE BY GAS CHROMATOGRAPHY by Jing‐tao Ma and Shi‐jie Lu, State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; Jing‐tao Ma and Wei Zhang, The Technology Center of Zhenhai Refining and Chemical Co. Ltd, Ningbo, China; and Ren‐ming Yu, Zhenhai Refining and Chemical Co. Ltd, Ningbo, China

ABSTRACT: A simple, fast, and reliable gas chromatographic method for the determination of purity and components in dimethyl carbonate (DMC) has been developed. The sample was seperated with a HP‐Wax polar capillary column and detected with a TCD detector using cyclopentanol as the internal standard. The quantitative determination of the components and trace water in the sample were carried out with the relative standard deviations less than 4.6% and the absolute errors less than 0.04%. The correction factors and linear relationship were obtained.

Analytical Letters, 37(12), 2557–2563, 2004

Abstract

POLYMER SUPPORTED HUMIC ACID FOR SEPARATION AND PRECONCENTRATION OF THORIUM(IV) by Sait Erdogan, Candan Hamamci, Osman Akba, and Akin Baysal, Chemistry Department, Faculty of Science and Arts, Dicle University, Diyarbakır, Turkey; and Melek Merdivan, Chemistry Department, Faculty of Science and Arts, Dokuz Eylul University Kaynaklar Campus, Buca35160, Izmir, Turkey

ABSTRACT: The resin impregnating humic acid (HA) onto XAD‐4 has been prepared to investigate adsorption behaviour of Th(IV). The characterization of the resulting resin has been carried out by infrared spectral data and sorption capacity. Maximum adsorption capacity of Th(IV) on the resin is found to be 1.51 × 10⁻⁴ mol g⁻¹ at pH 4. The sorbent was found to possess a high selectivity for Th(IV) with an optimum extraction pH around 3–7. Recoveries for Th(IV) determined prior to breakthrough were found to be quantitative (96–99%). The resin exhibits good chemical stability, reuseability, and a faster rate of equilibration for Th(IV) determination. The influence of several ions as interferents is discussed. The method has been successfully applied for the separation of Th(IV) in synthetic mixtures.

Analytical Letters, 37(12), 2565–2575, 2004

Abstract

EFFECT OF BOUND COPPER(II) ON THE LC SEPARATION OF SELECTED PHENOLS USING AN AMINOPHOSPHONIC ACID SILICA STATIONARY PHASE by Supalax Srijaranai, Watsaka Siriangkhawut, Somkiat Srijaranai, and Chaiwat Ruksakulpiwat, Department of Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand and Richard L. Deming, Department of Chemistry and Biochemistry, California State University, Fullerton California, USA

ABSTRACT: The effects of Cu (II) on the separation of phenol and chloro‐, nitro‐, and methyl‐substituted phenols by ligand exchange chromatography using the aminophosphonic acid silica (APAS) stationary phase were investigated. Retention times for the phenols were longer, and the peaks were more asymmetric with more tailing on APAS‐Cu(II) compared with the APAS. However, by using the mobile phase of hexane/dichloromethane/methanol and 5‐µm bonded APAS‐Cu (II) particles, good separation was achieved for a number of mixtures among the 12 compounds studied. This chromatographic system, however, did not resolve many of the most closely related compounds of interest. The order of elution can be explained by a separation mechanism involving complexation of phenols with Cu (II) on the APAS‐Cu (II) stationary phase, as well as van der Waals forces and hydrogen bonding. Excellent recovery, good linearity in response, and low detection limits (0.1–1 mg/L) were achieved. Capacity factors remained stable (1–2% relative standard deviation) for repeated column use over several days.

Analytical Letters, 37(12), 2577–2594, 2004

Abstract

SIMULTANEOUS SEPARATION AND PURIFICATION OF MICROCYSTIN LR, RR, YR BY USING SUPERCRITICAL FLUID EXTRACTION AND COLUMN CHROMATOGRAPHY by Dongjin Pyo, Changsuk Oh, and Jongchon Choi, Department of Chemistry, Kangwon National University, Chunchon 200‐701, Korea

ABSTRACT: An efficient method for the simultaneous separation and purification of microcystins (LR), (RR), and (YR) from the cyanobacterium is described. The method involves supercritical fluid extraction for the fast extraction and column chromatography for the purification of the microcystins LR, RR, and YR. A new method for the simultaneous extraction of microcystins LR, RR, and YR was developed by using supercritical CO₂. Three kinds of microcystins were successfully extracted with a ternary mixture (90% CO₂, 9.4% acetic acid, 0.6% water). The separation and purification procedure results in a purity of up to 95% for microcystins RR and YR without the need for a preparative high performance liquid chromatography (HPLC). Only for the purification of microcystin LR, we used a further preparative HPLC purification step. The advantage of the method developed here is that the sample handling steps were minimized, thus reducing possible losses of microcystins and saving extraction and purification time.

Analytical Letters, 37(12), 2595–2608, 2004

Abstract

SIMULTANEOUS SPECTROPHOTOMETRIC MULTICOMPONENT DETERMINATION OF FOLIC ACID, THIAMINE, RIBOFLAVIN, AND PYRIDOXAL BY USING DOUBLE DIVISOR–RATIO SPEC‐TRA DERIVATIVE–ZERO CROSSING METHOD by Jahanbakhsh Ghasemi, Bahman Abbasi, Ali Niazi, and A. Mordai, Department of Chemistry, Faculty of Sciences, Razi University, Kermanshah, Iran and E. Nadaf, Islamic Azad University, Ghochan Unit, Ghochan, Iran

ABSTRACT: A graphical method based on the double divisor–ratio spectra derivative–zero crossing was proposed for the spectrophotometric multicomponent analysis of synthetic mixtures containing folic acid (vitamin B₀), thiamine (vitamin B₁), riboflavin (vitamin B₂), and pyridoxal (vitamin B₆) in the presence of strongly overlapping signals without any chemical separation. The graphical method is based on the use of derivative signals of the ratio spectra by using double divisor. The selected data of ultraviolet‐visible absorption spectra consisted of points corresponding to the spectral region 225–475 nm. The linear determination ranges were 1–26 µg mL⁻¹ of B₀, 4–50 of µg mL⁻¹ B₁, 1–28 µg mL⁻¹ of B₂, 6–42 µg mL⁻¹ of B₆ in a buffer solution at (pH 5.8). The proposed method applied to the simultaneous determination of four vitamins by using synthetic quaternary mixtures. The obtained results were statistically compared with each other.

Analytical Letters, 37(12), 2609–2623, 2004

Abstract

ON ANALYTICAL USEFULNESS OF THE RECOVERY METHOD by Paweł Kościelniak, Department of Analytical Chemistry, Jagiellonian University30‐060, Kraków, Poland

ABSTRACT: The recovery method—applied increasingly frequently to studying the effectiveness of analytical procedures—is subjected to a detailed critical appraisal. Two versions of this method that have practical applications are presented, as are broad interpretation possibilities. Effects that may occur during the analytical procedure have been classified and the significance of these effects for the reliability of results gained by the recovery method has been defined. The similarities and differences between this method and the standard addition method have been indicated. Theoretical deliberations are supported by results of analysis of blood samples for selenium and arsenic content by the atomic fluorescence spectrometry method. It has been shown that the “surrogate” version of the recovery method, although potentially attractive from the analytical point of view, in practice can be very unreliable and the more complex the laboratory procedures for preparing the sample for measurement, the more risky is its application.

Analytical Letters, 37(12), 2625–2640, 2004