Abstracts

Abstract

DETERMINATION OF METALS IN CRUDE OIL BY ATOMIC SPECTROSCOPY by Carey Hardaway and Joseph Sneddon, Department of Chemistry, McNeese State University, Lake Charles, Louisiana, USA; James N. Beck, Department of Physical Sciences, Nicholls State University, Thibodaux, Louisiana, USA

ABSTRACT: Following an introduction to the origin and concentration of metals in crude oils, a brief overview of the major atomic spectroscopic methods, i.e., inductively coupled plasma‐atomic emission spectrometry, inductively coupled plasma‐mass spectrometry, and flame and graphite furnace atomic absorption spectrometry, and an overview of sample preparation/sample introduction are presented. Results are presented of a number of studies with V and Ni being the most widely determined metals in crude oil.

Analytical Letters, 37(14), 2881–2899, 2004

Abstract

ELECTROCHEMICAL DETECTION OF PROTEIN USING A DOUBLE APTAMER SANDWICH by Kazunori Ikebukuro, Chiharu Kiyohara, and Koji Sode, Tokyo University of Agriculture and Technology, Nakamachi, Koganei, Tokyo, Japan

ABSTRACT: We have developed an electrochemical sensor system for protein detection using two different antithrombin aptamers that recognize different parts of the target protein. In this case, thrombin was detected using a sandwich format comprised of a glucose dehydrogenase (GDH)‐labeled antithrombin aptamer and another aptamer that was immobilized onto the gold electrode for capturing the thrombin onto it. The electric current generated by the GDH when glucose was added was measured, and 1 µM of thrombin was detected selectively.

Analytical Letters, 37(14), 2901–2909, 2004

Abstract

ELECTROCHEMISTRY OF HEMOGLOBIN ON A GOLD COLLOID‐1,4‐BENZENEDIMETHANETHIOL MODIFIED ELECTRODE AND ELECTROCATALYTE DETECTION OF HYDROGEN PEROXIDE by Bin Fang, Guangfeng Wang, Xiaohong Yang, Qingqing Zha, Wenzhi Zhang, and Xianwen Kan, College of Chemistry and Material Science, Anhui Normal University, Wuhu, P.R. China

ABSTRACT: Hemoglobin (Hb) was successfully immobilized on gold nanoparticles (GNP) associated with a 1,4‐benzenedimethanethiol (BDT) monolayer on a gold electrode surface and was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Direct electron transfer (DET) between Hb and the modified electrode was achieved without the aid of any electron mediator. GNP can greatly promote the redox of Hb, on which a pair of obvious CV peaks for Hb Fe(III)/Fe(II) redox couple were obtained in pH 6.2 phosphate buffer solution (PBS). In pH 6.2 PBS, the formal potential (E°') of Hb was −0.180 V (vs. SCE), and the electron transfer rate constant was 5.2 s⁻¹. The formal potential of Hb on gold colloidal modified electrode shifts linearly with pH with a slope of −55.5 mV/pH at 20°C, showing that the electron transfer is accompanied by single proton transportation. The high efficiency of the Hb/GNP/BDT modified gold electrode toward the catalytic electroreduction of hydrogen peroxide has been observed. The immobilized Hb gave an excellent electrocatalytic response to H₂O₂. Potential application of Hb/GNP/BDT modified gold electrode as biosensors to monitor H₂O₂ is proposed.

Analytical Letters, 37(14), 2911–2924, 2004

Abstract

DETECTION OF ZINC AND LEAD IN WINE BY POTENTIOMETRIC STRIPPING ON NOVEL DENTAL AMALGAM ELECTRODES by Øyvind Mikkelsen, Camilla Nordhei, Silje M. Skogvold, and Knut H. Schrøder, Department of Chemistry, Norwegian University of Science and Technology, Trondheim, Norway

ABSTRACT: A simple method for detection of zinc and lead in wine by use of potentiometric stripping analyses (PSA) on the dental amalgam electrode is introduced and demonstrated for 10 different wines, both red and white. The combination of PSA and the novel nontoxic electrode offers a fast and easy‐to‐use technique without matrix effects seen in, e.g., voltammetry. Concentrations of zinc in the range of approximately 2.1 × 10⁻⁶ M to 11.7 × 10⁻⁶ M (3.5% std. dev.) and lead in the range of 9.7 × 10⁻⁸ M to 2.4 × 10⁻⁷ M (3.5% std. dev.) were found in the actual wine samples. PSA measurements were verified against atomic adsorption spectroscopy analyses (AAS), and a good correlation factor was found (r ² = 0.96). A simple speciation study was performed by measuring the amount of zinc and lead before and after the addition of acid, giving an approximate ratio between free and total amount of the metals. Estimated detection limits for zinc and lead were calculated to, respectively, 3.0 × 10⁻⁷ M and 1.5 × 10⁻⁸ M for 120 sec. of plating time.

Analytical Letters, 37(14), 2925–2936, 2004

Abstract

SYNTHESIS OF A NEW WATER‐SOLUBLE POLYMERIC PROBE AND ITS FLUORESCENT PROPERTIES FOR RATIOMETRIC MEASUREMENT OF NEAR‐NEUTRAL pH by Suying Dong, Huimin Ma, Xiaohua Li, Ming Sun, and Xuejun Duan, Laboratory of Chemical Biology, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China

ABSTRACT: A new water‐soluble polymeric fluorescent probe, poly[allylamine‐co‐N‐4‐chloro‐6‐(4‐methylcoumarin‐7‐oxy)‐1,3,5‐triazinylallylamine] (PA‐TMC), has been designed and characterized for near neutral pH measurement in dual‐excitation ratio application. The probe was synthesized by using cyanuric chloride as a linker, 7‐hydroxy‐4‐methylcoumarin as a fluorophore, and polyallylamine as a water‐soluble molecular scaffold. It showed a large pH‐dependent shift of excitation peak from 320–360 nm with no change of emission wavelength of 448 nm. The pK_a value of the probe was 7.56, and the ratio R (I₃₆₀/I₃₂₀) of fluorescence intensities at the two excitation wavelengths of 360 nm and 320 nm was directly proportional to pH values over the range 6.8–8.5, which may be suitable for the pH monitoring of near‐neutral systems. Spectroscopic properties of the probe were also compared to the corresponding low molecular weight 7‐(4,6‐dichloro‐1,3,5‐triazinoxy)‐4‐methyl‐coumarin (TMC). The results showed that the incorporation of TMC into a water‐soluble polymer bearing a large number of hard base ligands offers both considerably improved selectivity for H⁺ and solubility in water, suggesting that such a measure may be useful for preparing other probes with special functions.

Analytical Letters, 37(14), 2937–2948, 2004

Abstract

SPECTROPHOTOMETRIC DETERMINATION OF PEROXYNITRITE USING O‐PHENYLENEDIAMINE AS A PROBE by De‐Jia Li, Li‐Lin Wang, Xuan Zeng, and Guo‐Lin Zou, College of Life Sciences, Wuhan University, Wuhan, Hubei, P.R. China

ABSTRACT: In the present study, a novel spectrophotometric method for the determination of peroxynitrite using, o‐phenylenediamine as a probe is described. The method is based on the oxidation of o‐phenylenediamine, a colorless substance, by peroxynitrite to give a colored product. The absorbance increase of the reaction system is linearly related to the concentration of peroxynitrite in the range of 4.4 × 10⁻⁷–8.0 × 10⁻⁶ mol l⁻¹ with a detection limit of 1.7 × 10⁻⁷ mol l⁻¹ (3σ). The optimal conditions for the detection of peroxynitrite were evaluated and the possible detection mechanism was also discussed in this paper.

Analytical Letters, 37(14), 2949–2963, 2004

Abstract

ELEVATED FIBRINOGEN‐FIBRIN DEGRADATION PRODUCTS (FDP) IN SERUM OF COLORECTAL CANCER PATIENTS by Perry Rucker, Seashore Tetrachem, Inc., Santa Ana, CA, 92705, USA; Sheila M. Antonio, AMDL Inc., Tustin, CA, USA; and Barbara Braden, Medical Dept II, Johann Wolfgang Goethe University, Frankfurt/Main, Germany

ABSTRACT: Serum fibrinogen‐fibrin degradation product (FDP) levels of healthy control subjects and of patients with colorectal cancer have been measured by DR‐70^® ELISA in Frankfurt, Germany (Germany study) and in Tustin, California (U.S. study). Serum FDP levels of patients with colorectal cancer were significantly higher than those of the healthy controls. The median serum FDP levels in healthy control groups of the German and U.S. studies were, respectively, 0.37 µg/mL and 0.61 µg/mL. The median serum FDP levels in the colorectal cancer groups of the German and U.S. studies were, respectively, 1.25 µg/mL and 1.60 µg/mL. The results are consistent with enhanced fibrinolysis in serum of patients with colorectal cancer.

Analytical Letters, 37(14), 2965–2976, 2004

Abstract

DETERMINATION OF PAPAVERINE BY BIOTIN‐AVIDIN AMPLIFIED ELISA by Jin Yan, Jing Wang, Mei‐Ping Zhao, and Wen‐Bao Chang, The Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, P.R. China

ABSTRACT: Papaverine [1‐(3,4‐dimethoxybenzyl)‐6,7‐dimethoxyisoquinoline; PAP] is one of the most important alkaloids among the naturally occurring opium alkaloids. This work developed an indirect competitive enzyme‐linked immunosorbent assay (ELISA) for PAP based on the biotin‐avidin amplification system. The linear range of the calibration curve and the limit of detection (defined as three times of the blank) were 0.02–1000 ng/mL and 0.008 ng/mL, respectively. The established method was successfully applied to determining the concentration of PAP in the pericarpium papaveris with the recoveries between 88% and 120%. It was proved to be a highly sensitive and practical method for trace PAP detection compared with the existing gas chromatography‐mass spectrometry (GC‐MS) or high‐performance liquid chromatography (HPLC) methods.

Analytical Letters, 37(14), 2977–2989, 2004

Abstract

DETERMINATION OF HUMAN IgG BY SOLID SUBSTRATE‐ROOM TEMPERATURE PHOSPHORESCENCE IMMUNOASSAY by Jia‐Ming Liu, Huan‐Huan Xu, Ping‐Ping Li, and Bi‐Hua Chen, Department of Chemistry, Zhangzhou Normal College, Zhangzhou, P.R. China; Long‐Di Li, Department of Chemistry, Tsinghua University, Beijing, P.R. China; and Jian‐Ping Gao, Zhangzhou Chinese Medical Hospital, Zhangzhou, P.R. China

ABSTRACT: Silicon dioxide nanoparticle containing fluorescein isothiocyanate (FITC‐SiO₂) with the particle size of 20 nm was synthesized by solgel method. It can emit strong and stable solid substrate‐room temperature phosphorescence (SS‐RTP) signal on the substrate of polyamide membrane. It was found in the research that the specific reaction between goat‐antihuman IgG antibody labeled with FITC‐SiO₂ and human IgG (immunoglobulin) can be carried on the polyamide membrane quantitatively, the antigen‐antibody conjugate retained good phosphorescence properties, and the signal of phosphorescence was enhanced after the immunoassay reaction. Based on the facts above, a new method of solid substrate‐room temperature phosphorescence immunoassay (SS‐RTP‐IA) to determine human IgG was established. The linear range of this method is 0.080–20.0 pg human IgG spot⁻¹ (sample volume 0.40 µl spot⁻¹, and the corresponding concentration range of human IgG is 0.20–50.00 ng ml⁻¹). The regression equation of the working curve is ΔIp = 19.97 + 15.92 m _IgG (pg spot⁻¹), n = 6, correlation coefficient is 0.9997. The detection limit of this method calculated by 3 Sb/k is 0.015 pg spot^–1. Compared with the immunoassay using FITC to label goat‐antihuman IgG, the sensitivity was obviously improved. For the sample containing 0.20 (ng ml⁻¹) and 50.0 (ng ml^–1) human IgG, with a sample volume of 0.40 µl, the relative standard deviation (RSD) is 3.4% and 4.1% (n = 11), respectively. This indicated very good repeatability.

Analytical Letters, 37(14), 2991–3003, 2004

Abstract

ISOLATION OF STRUCTURALLY SIMILAR CITRUS FLAVONOIDS BY FLASH CHROMATOGRAPHY by Girija Raman, G.K. Jayaprakasha, and Bhimanagouda S. Patil, Texas A&M University–Kingsville Citrus Center, Weslaco, Texas, USA; Girija Raman, G.K. Jayaprakasha, and Bhimanagouda S. Patil, Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University, College Station, Texas, USA; and Jennifer Brodbelt and Minhee Cho, Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas, USA

ABSTRACT: A rapid and efficient method for the extraction and isolation of naringin and narirutin from citrus molasses is described. Naringin and narirutin are structurally similar glucosides present in citrus molasses. The common problem in purification of plant extracts is the large number of constituents present are similar in nature. A flash chromatographic technique has been developed for separation of the main flavonoid glucosides present in citrus molasses. This method is rapid, inexpensive technique and provides compounds with high purity that can be used for biological activity studies. The separation and yield of narirutin and naringin obtained by this method are reproducible.

Analytical Letters, 37(14), 3005–3016, 2004

Abstract

PREPARATION OF p‐TERT‐BUTYL‐CALIX[8]ARENE BONDED SILICA STATIONARY PHASE AND SEPARATION FOR STEROID HORMONE MEDICINES by Min Liu, Lai‐Sheng Li, Shi‐Lu Da, and Yu‐Qi Feng, Department of Chemistry, Wuhan University, Wuhan, P.R. China

ABSTRACT: p‐tert‐Butyl‐calix[8]arene bonded silica (CBS) gel stationary phase for high‐performance liquid chromatography was first prepared by condensation reaction between chloropropyl bonded silica (CPS) and phenolic sodium salt of p‐tert‐butyl‐calix[8]arene on solid phase surface. A new bonded stationary phase was characterized by elemental analysis, Fourier transform infrared (FTIR) analysis, and thermal analysis. The chromatographic behaviors on CBS for steroid hormone medicines were studied. The effect of mobile phase variables, such as methanol content, pH, ionic strength, and buffer composition, on the retention of solutes was investigated. The retention behaviors of steroid hormone medicines on CBS were compared with that on CPS and ODS. The retention mechanism of steroids on new stationary phases was also discussed. The results indicate that CBS exhibits π–π, hydrogen‐bonding, dipole–dipole interaction, and inclusion complexation besides hydrophobic interaction. Compared with ODS, separation speed increases, and consumption of organic solvent decreases. Steroid hormones were baseline separated with a half time on CBS opposed to ODS.

Analytical Letters, 37(14), 3017–3031, 2004

Abstract

HIGHLY SELECTIVE SEPARATION AND DETERMINATION OF MERCURY (II) USING N,N′‐BIS(2‐MERCAPTOPHENYL)ETHANEDIAMIDE by Derya Kara, Department of Chemistry, Art and Science Faculty, Balıkesir University, Balıkesir, Türkiye

ABSTRACT: The present work describes a selective and economical method for the determination of mercury using N,N′‐bis(2‐mercaptophenyl)ethanediamide (H₂L). The investigation included a study of the characteristics that are essential for solvent extraction and separation of mercury (II). Furthermore, a highly sensitive, selective, and rapid spectrophotometric method is described for the determination of trace amounts of mercury (II) by H₂L. This compound reacts with mercury (II) in the range of pH 2–10 to produce a red complex [1:1 mol ratio of Hg(II)/H₂L] soluble in dichloromethane. The complex was found to obey Beer's law from 5–128 µg mL⁻¹ with an optimum range when the preconcentration factor is one. The concentration limits in Beer's law are reduced from 0.2–5.12 µg mL⁻¹ with an optimum range when the preconcentration factor is 25. The relative standard deviations were calculated as 0.05% [15 samples, each containing 5 µg ml⁻¹ Hg (II)]. The precision was determined from 25 results obtained for 2.5 × 10⁻⁵ M Hg(II); the mean value of Hg(II) was 2.53 × 10⁻⁵ M with a standard deviation of 1 × 10⁻⁷ M Hg(II). The proposed method has been applied to the determination of mercury in water samples.

Analytical Letters, 37(14), 3033–3046, 2004

Abstract

STUDY OF TOXICITY AND VARIATION IN POLYPHENOL AND HYDROPEROXIDE CONTENT OF FOOD OILS SUBJECTED TO THERMAL STRESS OR USED FOR FRYING FOODSTUFFS by L. Campanella, L. Fisco, and M. Tomassetti, Department of Chemistry, “La Sapienza” University of Rome, P.le Aldo Moro, Roma; and R. Dragone, IMIP, sec. MICE–CNR, “La Sapienza” University of Rome, P.le Aldo Moro, Roma

ABSTRACT: An investigation was made of variations over time in the toxicity of extra‐virgin olive oil and peanut oil subjected to thermal stress (160–180°C), or used to fry potatoes at 160°C. In parallel, variations in polyphenol concentration and in that of hydroperoxides were monitored. Measurements were carried out using a suitable toxicity measuring device consisting of an oxygen sensor plus yeast cells or enzymatic biosensors, for the phenols and hydroperoxides, respectively.

Analytical Letters, 37(14), 3047–3061, 2004

Abstract

COMPARISON OF DIFFERENT EXTRACTION METHODS APPLIED TO VOLATILE COMPOUNDS IN WINE SAMPLES PREVIOUS TO THE DETERMINATION BY GAS CHROMATOGRAPHY by S. Cabredo‐Pinillos, T. Cedrón‐Fernández, and C. Sáenz‐Barrio, Edificio Científico‐Tecnológico, Departamento de Química (Química Analítica), Universidad de La Rioja, Logroño, España

ABSTRACT: This paper describes the optimization and comparison of discontinuous liquid–liquid extraction, continuous liquid–liquid extraction and solid‐phase extraction as methods for separating and concentrating volatile compounds from wine. The study has been applied to 11 compounds present in wine: 3‐methyl‐butyl acetate, 3‐methyl‐1‐butanol, ethyl hexanoate, 1‐hexanol, ethyl octanoate, diethyl succinate, 2‐phenyl‐ethyl acetate, hexanoic acid, 2‐phenyl‐ethanol, octanoic acid, and decanoic acid. These compounds were selected from those identified by gas chromatography‐mass spectrometry (GC‐MS) analysis of a natural wine sample. Factors such as the sample volume, the extraction time, and the solvent volume were considered. In all cases, the determination was performed by gas chromatography, using a flame ionization detector and the internal standard method (3‐octanol) as the quantification procedure.

The optimization study was performed with synthetic wine samples containing all the volatile compounds under study. The solid‐phase extraction was subsequently applied to samples of red wines from La Rioja.

Analytical Letters, 37(14), 3063–3084, 2004

Abstract

APPLICATION OF MULTIWALLED CARBON NANOTUBES AS A SOLID‐PHASE EXTRACTION SORBENT FOR CHLOROBENZENES by Guohong Liu, Yongfa Zhu, and Xinrong Zhang, Department of Chemistry, Key Laboratory of Atomic and Molecular Nanosciences of Education Ministry, Tsinghua University, Beijing, China; Jinglin Wang, Department of Chemistry, Changzhi College, Changzhi, China

ABSTRACT: Carbon nanotubes are novel and interesting nanomaterials in the field of nanometer research because of their many unique electronic, mechanical, and chemical properties. Therefore, the application of carbon nanotubes in analytical chemistry is of great interest. In our work, a trace enrichment method based on the application of multiwalled carbon nanotubes (MWNTs) as a solid‐phase extraction (SPE) sorbent for chlorobenzenes was developed. The SPE conditions affecting extraction recoveries, including the sample volume, the type of eluents, the volume, and the flow rate of eluent, were optimized. The adsorption characteristic was compared between MWNTs and current SPE sorbents, including C₁₈ silica and activated carbon. The results showed that the adsorption capacities of MWNTs, C₁₈ bonded silica, and activated carbon for 1,2‐dichlorobenzene at an equilibrium concentration of 90 µg/mL were 237, 189, and 150 mg/g, respectively. The results also showed that MWNTs had higher extraction recoveries for chlorobenzenes. This method would be applied to the determination of chlorobenzenes as well as persistent organic pollutants (POPs) in natural and polluted waters.

Analytical Letters, 37(14), 3085–3104, 2004