Using Raman spectroscopy without any preparation, we analyzed the brominated flame retardant, polybromodiphenyl ethers (PBDEs), which has been prohibited by the European Union. The typical Raman bands of PBDEs, which are clearly different from those of other brominated flame retardants, are from 100 to 300 cm^-1. In our analysis, the detection limit was about 100 ppm, and the analysis took about 1 min, whereas the usual method of solvent extraction using gas chromatography/mass spectroscopy takes 50 h.

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The objective of this study is to analyze the technical importance, performance, techniques, advantages, and disadvantages of the biosensors in general and of the electrochemical biosensors in particular. A product of reaction diffuses to the transducer in the first generation biosensors (based on Clark biosensors). The mediated biosensors or second generation biosensors use specific mediators between the reaction and the transducer to improve sensitivity. The second generation biosensors involve two steps: first, there is a redox reaction between enzyme and substrate that is reoxidized by the mediator, and eventually the mediator is oxidized by the electrode. No normal product or mediator diffusion is directly involved in the third generation biosensors, direct biosensors. Based on the type of transducer, current biosensors are divided into optical, mass, thermal, and electrochemical sensors. They are used in medical diagnostics, food quality controls, environmental monitoring, and other applications. These biosensors are also grouped under two broad categories of sensors: direct and indirect detection systems. Moreover, these systems could be further grouped into continuous or batch operation. Therefore, amperometric biosensors and their current applications are focused on more in detail since they are the most commonly used biosensors in monitoring and diagnosing tests in clinical analysis. Problems related to the commercialization of medical, environmental, and industrial biosensors as well as their performance characteristics, their competitiveness in comparison to the conventional analytical tools, and their costs determine the future development of these biosensors.

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The interaction of a copper-bipyridyl (bpy) complex with CT-DNA was investigated by voltammetry, absorption and fluorescence spectrophotometry. The binding constant of the Cu(bpy)₂²⁺ complex interacting with DNA was 3.24 × 10⁴ L/mol and the ability binding of Cu(bpy)₂²⁺ to DNA was 1.3-times as large as that of Cu(bpy)₂⁺ to DNA. DNA could be efficiently cleaved by a potential-modulated method in the presence of the Cu(bpy)₂²⁺ complex. The fragments of the cleaved DNA were separated by high-performance liquid chromatography (HPLC). The experimental results revealed that the proposed method for DNA cleavage is highly efficient.

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A novel biochemical sensor was fabricated on a carbon fiber microelectrode, which consisted of an inner layer of electrodeposited gold nanoparticles, as a nano-array electrode, and an outer layer of electrodeposited calf thymus ds-DNA at +1.5 V vs. SCE. This modified electrode was characterized by X-ray photoelectron spectroscopy, scanning electron microscope, atomic force microscopy, cyclic voltammetry and differential pulse voltammetry (DPV). It was found that this electrochemical sensor exhibits a strong catalytic activity toward the oxidation of dopamine (DA), serotonin (5-HT) and ascorbic acid (AA), as a result of resolving the anodic voltammetric peaks of DA, 5-HT and AA into three welldefined peaks. Simutaneous DPV determination of DA and 5-HT can be achieved in the presence of 2000-fold AA. The modified electrode shows good sensitivity, selectivity and stability.

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The construction and general performance of thirteen new polymeric membrane sensors for the determination of fexofenadine hydrochloride based on its ion exchange with reineckate, tetraphenylborate and tetraiodomercurate have been studied. The effects of membrane composition, type of plasticizer, pH value of sample solution and concentration of the analyte in the sensor internal solution have been thoroughly investigated. The novel sensor based on reineckate exchanger shows a stable, potentiometric response for fexofenadine in the concentration range of 1 × 10^-2 - 2.5 × 10^-6 M at 25°C that is independent of pH in the range of 2.0 - 4.5. The sensor possesses a Nernstian cationic slope of 62.3 ± 0.7 mV/concentration decade and a lower detection limit of 1.3 × 10^-6 M with a fast response time of 20 - 40 s. Selectivity coefficients for a number of interfering ions and excipients relative to fexofenadine were investigated. There is negligible interference from almost all studied cations, anions, and pharmaceutical excipients, however, citrizine that has a structure homologous to that of fexofenadine was found to interfere. The determination of fexofenadine in aqueous solution shows an average recovery of 99.83% with a mean relative standard deviation (RSD) of 0.5%. Direct potentiometric determination of fexofenadine in tablets gave results that compare favorably with those obtained by standard spectrophotometric methods. Potentiometric titration of fexofenadine with phosphomolybdic acid as a titrant has been monitored with the proposed sensor as an end point indicator electrode.

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We propose an electron transfer-mediated amperometric enzyme biosensor based on plasma-polymerized thin film of dimethylaminomethylferrocene (DMAMF) on a sputtered gold electrode. The DMAMF plasma-polymerized film is deposited directly onto the surface of the electrode under dry conditions. The resulting thin film not only has redox sites but also is extremely thin (∼20 nm), adheres well onto the substrate (electrode), has a flat surface and a highly-crosslinked network structure, and is hydrophilic in nature. Glucose oxidase is densely immobilized onto the surface of DMAMF plasma-polymerized film on the gold electrode. From the electrochemical measurement, the biosensor can cover the wide range of glucose concentration (1.3 - 81 mM) at +350 mV of applied potential. The current response of the glucose biosensor was decreased by less than 5% in an aerobic solution as compared to that in an anaerobic solution. These show that the DMAMF plasma-polymerized films play a role as the electron transfer mediators between the reaction center of enzyme and the electrode.

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According to the strong application background of bioflavonoid and metal-flavonoid complexes, novel electrospray ionization tandem mass spectrometry (ESI-MSⁿ) was applied to investigate the structure and fragmentation mechanism of transition metal-rutin complexes. In the full-scan mass spectra, different stoichiometric ratios of rutin-metal complexes were found. In the reaction between rutin and Cu, four kinds of complexes with four different stoichiometric ratios were produced. In the reaction between rutin and Zn, Mn(II), and Fe(II), only two kind of complexes with stoichiometric ratios of 1:1 and 1:2 occured. In further tandem mass spectrometric experiments of different rutin-metal complexes, product fragments came from the neutral loss of the external rhamnose and the internal glucose unit, oligosaccharide chain, aglycone, and small organic molecules. According to the MSⁿ data, we proposed a mechanism for all fragments of the rutin-Cu complex A and the structure of two rutin-Cu complexes, C and D.

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An organic/inorganic hybrid compound consisting of methylene blue, a cationic surfactant and a reductant intercalated into saponite was found to serve as an oxygen indicator that changes color in the presence of oxygen. A mixture of a blue colored dye, methylene blue, a reductant in the form of ascorbic acid or reducing sugar, and cetyltrimethylammonium ion intercalated into synthetic saponite became colorless in an atmosphere having an oxygen concentration of less than 0.1 vol%, and then returned to its blue color as a result of subsequent exposure to air. An oxygen indicator, in the form of a thin film coated on paper prepared by adding a pigment, phloxine B, to the above organic/inorganic hybrid compound, exhibited a pink color at oxygen concentrations of less than 0.1 vol%, and a blue color at oxygen concentrations of higher than 0.5 vol%. In addition, this oxygen indicator exhibited superior photo-fading resistance and storage stability compared with indicators using only methylene blue as the functional dye.

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Sensitive visual and micro spectrophotometric methods have been developed for field determination of trace iron in fresh water samples. For the visual method, a water sample (0.45-µm filtrate acidified to 0.1 M HCl) was placed in a glass vial and mixed with a reagent solution containing 1,10-phenanthroline, sodium thiocyanate and 0.1 M HCl. Iron was extracted as pink ferroin thiocyanate with 1 ml of 4-methy-2-pentanone. The sample up to 20 ml was added step-by-step, until the color of the extract was detected visually. Without any special instrument or color standard, iron down to 0.001 mg l^-1 (0.025 µg) in a sample can be determined with an error of 20% in the field. For the micro spectrophotometric method, the extract for 20 ml of sample was separated by capillary suction in a column (micro pipette chip) with acrylic fibers. A part of the extract was pushed out into a micro cell for the absorbance measurement at 525 nm. The column was re-usable after washing with ethanol. This method had a detection limit of 0.001 mg l^-1 and allowed determinations within an error of 5%. The proposed methods were applied to deionized-, tap-, river-, lake- and reservoir-water samples.

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Polymer-supported liquid-crystal membranes have been designed for neutral-carrier-type potassium ion-selective electrodes, aiming for practical applications of high-performance liquid-crystalline membrane ion sensors. Two types of polymer-supported liquid-crystal membranes were tested for their usefulness; one is microporous poly(tetra fluoroethylene) (PTFE) membranes impregnated by thermotropic liquid-crystalline compounds, and another is poly(methyl methacrylate) (PMMA) membrane dispersing the same liquid-crystalline compounds. Both of the polymersupported liquid-crystal membranes containing a liquid-crystalline benzo-15-crown-5 neutral carrier as well as a lipophilic anion excluder work well as ion-sensing membranes for potassium ion-selective electrodes, the ion selectivities of which can be switched by the measurement temperatures. Specifically, PTFE-impregnated liquid-crystal membranes are better than the PMMA-dispersed ones in the sensitivity and selectivity of the resulting ion electrodes. A potassium ion assay in blood sera has proved that neutral-carrier-type ion-selective electrodes based on the polymer-supported liquid-crystal membranes are reliable for practical uses.

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In order to demonstrate the activation effects of a Pt electrode by laser pulse irradiation, the electro-oxidation of glucose was tested at an activated Pt electrode by cyclic voltammetry. A fixed potential was applied to the electrode, and then the electrode was irradiated with laser pulses from a Nd:YAG laser at 20 Hz for 20 s. Activation by the laser pulse irradiation gave two remarkable effects on cyclic voltammograms from the electro-oxidation of glucose in a 0.1 mol dm^-3 NaOH solution, i.e., surface modulation and cleaning effects. Significant differences were found in the cyclic voltammograms at the activated and at the simply polished electrodes. Such differences in the oxidation waves are attributed to a crystallographic change of the electrode surface induced by a laser ablation, accompanied by laser pulse irradiation. Due to the cleaning effect, the activated Pt electrode gave a sharp oxidation wave at -0.3 V even in real samples containing various organic compounds that could foul the electrode, though the activated Pt electrode lacked selectivity to the electro-oxidation of glucose.

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The electrochemical reduction of 1-{[(4-halophenyl)imino]methyl}-2-naphthols on graphite electrodes was studied using cyclic voltammetry, chronoamperometry, constant-potential coulometry and preparative constant-potential electrolysis techniques. The data revealed that the reduction on graphite was irreversible and followed an EC mechanism. The diffusion coefficients and the number of electrons transferred were determined using the chronoamperometric Cottrell slope and the ultramicro disc Pt-electrode steady-state current. The number of electrons was also determined by bulk electrolysis. The compounds were subjected to constant-potential preparative electrolysis and the electrolysis products were purified and identified by spectroscopic methods. Based on these findings, a mechanism for the electro-reduction process is proposed.

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A novel selective thiocyanate electrode of a PVC membrane based on bis-[N-(2-hydroxyethyl)salicylaldimino]copper(II) [Cu(II)-BNSDM] as a neutral carrier is reported. The selectivity sequence of this electrode is as follows: SCN^- > ClO₄^- > I^- > Sal^- > Br^- > NO₂^- > Cl^- > NO₃^- > H₂PO₄^- > SO₄^2-, which is an anti-Hofmeister selectivity sequence. The electrode exhibits a Nernstian potential linear range to thiocyanate from 1.0 × 10^-1 to 6.0 × 10^-6 mol/L with a detection limit of 2.0 × 10^-6 mol/L and a slope of (-59.0 ± 0.2)mV/decade in pH 5.0 of a phosphate buffer solution at 25°C. Electrochemical impedance spectroscopy (EIS) and UV spectroscopy techniques were performed to understand the response mechanism of the electrode. The electrode had the advantage of simplicity, high selectivity, fast response and low detection limit compared with the other electrode, which had been reported before. The electrode had been applied to wastewater analysis, and the obtained results were satisfactory.

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This paper describes a versatile technique for amino-acid separation using a novel low-capacity sulfoacylated macroreticular polystyrene-divinylbenzene cation-exchange column with a simple binary high-pressure pH gradient elution. Proteinic 16 amino acids were well separated within 50 min using a H₃PO₄/Na₂HPO₄-CH₃CN eluent system, and the cycle time was about 70 min. The chromatography with postcolumn OPA fluorescent detection was reproducible with RSDs less than 1% for retention times, and was quantitative with RSDs less than 5% for area responses. A linear regression line with an r² value above 0.9990 was obtained for each analyte in concentration from 0.1 to 10 µM by 20 µL injection. The method was applicable to the separation and detection of urinary diagnostic amino acid due to inborn errors of metabolism, such as phenylketonuria. The analytical costs would be decreased by using the proposed method.

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Dioxouranium together with copper(II), nickel(II) and iron(II) were extracted in chloroform as complexes of bis(salicylaldehyde)-dl-stilbenediimine (dl-H₂SA₂S) or bis(salicylaldehyde)-meso-stilbenediimine (meso-H₂SA₂S), and separated by liquid chromatography with UV detection. The linear calibration range and detection limits were 40 - 200 ng and 10 ng/injection for each metal ion. The method was applied to the determination of uranium from mineral ore samples at concentrations of 30 - 700 µg/g with coefficients of variation from 3.6 to 5.5%. The relative elution of dioxouranium complexes of different Schiff bases was examined from reversed-phase HPLC; the substitution of methyl and phenyl groups at the bridge position enhanced the column retention of uranyl complexes.

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The H-point standard addition method (HPSAM), based on a spectrophotometric measurement for the simultaneous determination of hydrazine and acetylhydrazine, is described. This method is based on the difference between the rates of their reactions with N,N-dimethylaminobenzaldehyde (DAB) in the presence of sodium dodecyl sulfate (SDS) in acidic media. The results showed that hydrazine and acetylhydrazine could be determined simultaneously in the range of 0.020 - 0.70 and 0.20 - 5.0 mg L^-1, respectively. Under the working conditions, the proposed method was successfully applied to the simultaneous determination of hydrazine and acetylhydrazine in several synthetic mixtures and plasma and water samples.

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A sequential injection methodology for the spectrophotometric determination of calcium, magnesium and alkalinity in water samples is proposed. A single manifold is used for the determination of the three analytes, and the same protocol sequence allows the sequential determination of calcium and magnesium (the sum corresponds to the water hardness). The determination of both metals is based on their reaction with cresolphtalein complexone; mutual interference is minimized by using 8-hydroxyquinoline for the determination of calcium and ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA) for the determination of magnesium. Alkalinity determination is based on a reaction with acetic acid, and corresponding color change of Bromcresol Green. Working ranges of 0.5 - 5 mg dm^-3 for Ca, 0.5 - 10 mg dm^-3 for Mg, and 10 - 100 mg HCO₃^- dm^-3, for alkalinity have been achieved. The results for water samples were comparable to those of the reference methods and to a certified reference water sample. RSDs lower than 5% were obtained, a low reagent consumption and a reduced volume of effluent have been accomplished. The determination rate for calcium and magnesium is 80 h^-1, corresponding to 40 h^-1 per element, while 65 determinations of alkalinity per hour could be carried out.

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Applications of X-ray fluorescence (XRF) analysis with a pyroelectric X-ray generator are presented. Glass and ceramics were analyzed with this novel X-ray generator to examine its capability for analyzing nonmetallic inorganic material. Although the power of X-ray output was a few orders of magnitude lower than conventional X-ray tubes, many elements such as Si, K, Ca, Ti, Cr, Fe, Zn, Sr, Ba, and Pb were detected in glass and ceramic samples. Light elements such as Na, Mg, and Al were not detected because of the low fluorescence yield and the absorption of fluorescent X-rays in air. The elements detected or the relative peak intensities of the elements were different from each other, and the samples analyzed were identified by the XRF spectrum, notwithstanding the low power of the X-ray output. This novel device showed the sufficient capability for preliminary screening before strict identification of analytes. The pyroelectric X-ray generator can also be used to analyze large samples that cannot be put into ordinary XRF spectrometers because the device has no dimensional limitation of analytes.

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Agarose-supported BLMs were prepared by the tip-dip and painting methods, and single-channel recordings of gramicidin were examined for the development of an ion-channel sensor. The supported BLMs formed by the tip-dip method had an electric resistance of >1.0 × 10¹¹ Ω and a longer lifetime as compared with unsupported ones, which enabled single-channel recordings of gramicidin. The supported BLMs formed by the painting method also enabled single-channel recordings, but the lifetime was shorter than that of unsupported planar BLMs formed by the monolayer folding method.

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Two ideas for characterizing the local structure in mixed self-assembled monolayers (SAMs) were introduced. First, to use thermal desorption mass spectrometry (TD-MS) to probe nearest neighborhoods in the mixed monolayers. Second, to use hydrogen/deuterium exchange as a probe of the accessibility of acidic protons to exchange. Neighborhood interactions provided an opportunity to observe microscopic phase changes at the SAMs surface as a function of the OH-terminal ratio. H/D exchange between surficial OH-terminal SAMs and D₂O was successfully observed. H/D exchange was of importance in characterizing the surface properties and molecular basis interactions for the design of bio-interface structures using self-assembled monolayers.

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The formed cobalt-α-benzilmonoxime complex was adsorbed onto microcrystalline naphthalene. Then it was determined by zero and first derivative spectrophotometry and by atomic absorption spectrophotometry (AAS) after dissolving into chloroform and methylisobutylketone (MIBK), respectively. Under optimum conditions, cobalt in the range of 1.0 - 20.0, 0.4 - 30.0 and 2.5 - 50.0 µg could be determined by spectrophotometry, first derivative spectrophotometry and AAS method, respectively. By the method, a preconcentration factor equal to ∼30 for cobalt was obtained. The effect of diverse ions on the determination of 5.0 µg cobalt was also studied. The method was successfully applied to some pharmaceuticals and synthetic alloy samples.

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Two simple, sensitive and economical spectrophotometric methods have been developed for the determination of amiodarone hydrochloride in pure form and commercial dosage form. These methods (A and B) are based on the reaction of amiodarone base as n-electron donor with p-chloranilic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as π-acceptors to give highly colored complex species which absorb maximally at 535 and 570 nm, respectively. Beer’s law is obeyed in the concentration ranges 10.0 - 360.0 and 2.0 - 65.0 µg ml^-1 for methods A and B, respectively. Application of the proposed methods to commercial pharmaceutical tablets are presented.

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A new luminescence-enhancement system based on complex formation between europium and sparfloxacin in the presence of lutetium in a sodium dodecyl sulfate solution has been discovered. By adding a suitable amount of Lu³⁺ to the Eu-sparfloxacin-sodium dodecyl sulfate system, the luminescence can be enhanced by approximately 5-fold compared with that of the system without Lu³⁺. Under the optimum conditions, the luminescence intensity of the system is a linear function of the concentration of europium in the range of 1.0 × 10^-10 - 5.0 × 10^-7 mol L^-1. The detection limit of europium is 2.0 × 10^-13 mol L^-1 (S/N = 3). The system was used for the determination of trace amounts of europium in rare earth samples with satisfactory results.

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