Thermal desorption (TD)-GC/MS, recently developed for the determination of DeBDE in a polystyrene (PS) sample to an order of a few %, was evaluated in detail by using a certified standard PS sample containing 317 ppm of DeBDE. Not only the accuracy and precision of the results, but also the linearity of the working calibration curve were discussed in terms of the catalytic decomposition of DeBDE induced by the degrading macro-radical of the matrix polymer.

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To simply evaluate toxicity for various types of exhaust-gas samples collected in various locations, we developed a small-scale (150 mL) batch-type completely closed gas exposure device incorporated with an air-liquid interface culture of a human alveolar epithelial cell line, A549. On the basis of cell viability tests using an acid phosphatase assay after 48 h of gas exposure, the developed device was able to measure clear dose-response relationships for volatile organic and inorganic compounds, such as benzene, trichloroethylene (TCE), acetone, SO₂ and NO₂ gases, but not CO gas. Although the 50% effective concentration values in the device were much higher than 50% lethal concentration values reported in animal experiments, the tendency of the toxic intensity observed in the former was roughly consistent with that of the acute toxicity in the latter. We further applied the device to evaluate the toxicity of cigarette smoke as an example of actual environmental gases, and successfully measured acute cell death from the gas after 48 h of exposure. The present small device is expected to be one of good tools not only in simultaneously assessing various gaseous chemicals or samples, but also in studying acute toxicity expression mechanisms in human lung epithelia.

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An analytical method, based on separation with gas chromatography (GC) and detection with optical fiber (OF), was used for the separation, detection and quantification of benzene, toluene, ethylbenzene, p-xylene, m-xylene and o-xylene. The use of OF as a detector is based on the variations of the reflected optical power detected when the aromatic compounds eluted from the GC column are sorbed in a thin polymeric film on a single-mode OF. General figures of merit, such as the analytical time, analytical error and analytical performance of GC-OF were similar to those of the classical analytical methods, such as a gas chromatography-flame ionization detector (GC-FID). However, the developed GC-OF method constitutes a much less expensive alternative for the speciation of aromatic hydrocarbons compounds, with high accuracy, and being most suitable for actual monitoring work on confined environments.

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An in situ nitric acid analyzer has been designed for sensing in the remote atmosphere. Its operation is based on measuring the concentration difference between the total odd nitrogen species (NO_y) and HNO₃-scrubbed NO_y. NO_y was measured by an NO-ozone chemiluminescent detector equipped with a molybdenum converter. A temperature-controlled annular denuder coated with NaCl was used as a scrubber of gaseous HNO₃. The current detection limit of the HNO₃ analyzer was estimated to be 158 and 71 pptv (parts per trillion by volume) with an integration time of 2 and 10 min (2σ), respectively. The analyzer was calibrated using standard gaseous HNO₃ to verify its performance. The HNO₃ concentrations measured by the scrubber difference and the NO-ozone chemiluminescence methods (SDCL method) were in agreement with those obtained by the denuder method within the experimental uncertainties (more than ±4%). We conducted limited field observations of NO_y and HNO₃ in the remote atmosphere using the newly designed SDCL method at Cape Hedo, Okinawa, Japan.

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Triazines comprise an important pollutant class owing to continued use in certain countries, and owing to strong environmental persistence that leads to problems even in countries like Sweden where the use of triazines has been prohibited for some years. We investigated mass-selective detection for analysis of triazines. More specifically, we studied the background reduction and sensitivity enhancement that result from the use of a new interface technique, field-asymmetric ion mobility spectrometry (FAIMS), in conjunction with electrospray ionization ion-trap mass spectrometry. This technique allows for ion sorting and discrimination against the considerable “chemical noise”, nonspecific cluster and fragment ions, which are typically generated in electrospray ionization. This paper presents results of a pilot study of triazines and some metabolites in ideal solvents. Our long-range goal is automated analysis with mass-selective detection coupled to membrane-based sample cleanup and enrichment for additional enhancement in sensitivity.

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A novel and simple flow injection chemiluminescence method is reported for the determination of simetryn, a common herbicide. The method is based on the direct oxidation of luminol by the photoproducts of the simetryn in alkaline medium in the absence of catalyst/oxidant. The linear concentration range was 0.01 - 2 µg mL^-1 simetryn with a correlation coefficient (r²) of 0.9997 and relative standard deviations (RSD; n = 4) in the range of 0.9 - 2.3%. The limit of detection (S/N = 3) was 7.5 ng mL^-1 with a sample throughput of 100 h^-1. The proposed method has been applied to determine simetryn in natural waters using Sep-Pak C₁₈ cartridges for solid phase extraction (SPE) procedure. The recoveries were in the range of 97 ± 1 to 104 ± 2%. The mechanism of chemiluminescence reaction has also been discussed briefly.

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An automated multi-pumping flow system is proposed for the simultaneous chemiluminometric determination of benserazide and levodopa using multivariate calibration methods. The developed methodology is based on chemiluminescence (CL) emission generated by the reaction of benserazide with luminol, and on a concurrent inhibiting effect of levodopa on this reaction. A multi-pumping flow system comprising multiple solenoid micro-pumps as the only active components was developed to implement a stopped-flow approach for signal acquisition and processing. Artificial neural networks were used to establish a relationship between the CL emission profile and the concentration of both drugs. The concentration values used to establish the experimental calibration samples were varied between 5 and 30 mg l^-1 for levodopa and between 2.5 and 20 mg l^-1 for benserazide. The proposed method was successfully applied to the simultaneous determination of levodopa and benserazide in pharmaceutical formulations combining both drugs.

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The interactions between Cu(II) complexes with heterocyclic azo compounds and several anions were studied by equilibrium analysis of ion-pair extraction, RP-HPLC of metal complexes, and ion chromatography of anions on an ODS column coated with Cu(II) complexes of the long alkyl derivatives. Both ion-pair extraction and HPLC studies demonstrated that a dicationic complex with 8-(3,5-dibromo-2-pyridylazo)-5-aminoquinoline interacted with anions stronger than a monocationic complex with 2-(2-pyridylazo)methylphenol. Anions were more retained on the column coated with dicationic Cu(II) complex. Such differences were quantitatively ascribed to the first ion-pair formation of the dicationic complex giving a monocationic species.

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The ion-pair formation constants {K_j⁰: j = MA (metal salt), MLA} of NaO₂CCF₃ (Na⁺tfa^-) and its ion-pair complexes (MLA) in water (w) were determined potentiometrically at 25°C and an ionic strength (I) of zero. 15-Crown-5 (15C5), 18-crown-6 ethers (18C6), and their mono-benzo derivatives were used as crown ethers (L). The extraction of Natfa by these four L from w into 1,2-dichloroethane was done at 25°C, and then the extraction constants (K_ex) for NaLtfa were calculated by using the K_j values, which were estimated from the corresponding K_j⁰ ones at I of the w-phases, and other equilibrium constants. Also, the distribution constants (K_D,MLA) of NaLtfa between the two phases were obtained from a thermodynamic cycle expressing K_ex. An interaction of w-molecules with NaLA was considered using a relation of log K_D,MLA with log K_D,L, derived from the Scatchard-Hildebrand equation, where K_D,L denotes the distribution constant of L between the two phases. The interaction increased in the order of NaL (picrate) < free L ≤ NaLMO₄ (M = Mn, Re) < NaLtfa for L = 15C5 and 18C6.

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The structural speciation aspects, including the binding sites, species, complexation abilities and effects of the oxidized glutathione (GSSG) with aluminum(III) in aqueous solutions, have been studied by means of many analytical techniques: pH-potentiometry (25°C, 0.1 M KCl and 37°C, 0.15 M NaCl medium) was used to characterize the stoichiometry and stability of the species formed in the interactions of the Al(III) ion and the peptide GSSG, while multinuclear (¹H, ¹³C, ²⁷Al) nuclear magnetic resonance (NMR) and electrospray mass spectroscopy (ESI-MS) were applied to characterize the binding sites and species of the metal ion in the complexes. Two-dimensional (¹H, ¹H-NOESY) was also employed to reveal the difference in the conformational behavior of the peptide and its complexes. The following results were obtained: (1) Aluminum(III) can coordinate with the important biomolecule GSSG through the following binding sites: glycyl and glutamyl carboxyl groups to form various mononuclear 1:1 (AlLH₄, AlLH₃, AlLH₂, AlLH, AlL, AlLH_-1, AlLH_-2) and several binuclear 2:1 (Al₂LH₄, Al₂LH₂, Al₂L) species (where H₆L²⁺ denotes the totally protonated oxidized glutathione) in acidic aqueous solutions. (2) It indicates that the COO^- groups at low level of preorganization in such small peptide are not sufficient to keep the Al(III) ion in solution and to prevent the precipitation of Al(OH)₃ in the physiological pH range. (3) It also suggests that the occurrence of an Al-linked complexation, the conformation of the peptide GSSG in aqueous solutions appeared to change a little, relative to the initial structure.

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A novel method using a micro-column packed with active alumina as solid phase was proposed for separation of trace lithium from uranium compounds prior to determination. The method is based on a preliminary chromatographic separation of the total amount of uranium. This separation involves passing the solution containing sodium carbonate through active alumina and then eluting the trace lithium retained by the solid phase with a solution of sulfuric acid. Two modes, off-line and on-line micro-column preconcentration, were performed. In conjunction with atomic absorption spectrometry, this on-line preconcentration technique allows a determination of lithium at 10^-9 level. Both off-line and on-line mode operation conditions were investigated in separation and determination of trace lithium by micro-column method (length of column bed, flow rate, etc.). The adsorption capacity of activated alumina was found to be 343 µg g^-1 for lithium. Under the optimal operation condition, the detection limit (DL) of on-line preconcentration corresponding to three times the standard deviation of the blank (S/N = 3) was found to be 1.3 ng mL^-1 and the RSD of this method is 3.32% (n = 5). The on-line calibration graph was linear over the range 20 - 200 ng mL^-1. A good preconcentration factor 820 was achieved by experiment under the on-line mode. The developed method was applied to the analysis of trace lithium in nuclear grade uranium compounds.

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Resveratrol, existing in two isomeric trans-and cis-forms, is a phytoalexin that has pharmacological activities, like anti-cancer and anti-cardiovascular diseases as well as life-span increasing properties. Grapes are good sources for resveratrol introduction in the human diet not only directly, but also through its products: wine. In the present work, trans-resveratrol determination and the separation of resveratrol isomers were investigated by the use of micro-high performance liquid chromatography. The analysis conditions were optimized. The baseline separation of trans-and cis-resveratrol was obtained. Further, a trans-resveratrol determination of some grapes growing in Shacheng, Huailai, Hebei province, China was carried out with our analytical method. The concentrations were 6.77 ± 0.12 and 3.95 ± 0.18 (µg/g fresh weight) for merlot and cabernet sauvignon grapes, respectively.

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A novel, high-performance wide-bore electrophoresis (WE) system with inner-cooling has been developed. By introducing the mode of a shell and tube heat exchanger into this system to remove Joule heat generated during electrophoresis, it is feasible to extend electrophoresis from the conventional capillary (i.d. <100 µm) to a wide-bore tube (i.d. >1000 µm). The wide tube allows the loading of over 1.0 µL of the sample with an LOD of 3.0 × 10^-4 mg/mL (signal-to-noise ratio, 3:1). Satisfactory separations of model compounds have been achieved on the WE system.

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A simple, effective, and sensitive online concentration method for the detection of dextromethorphan hydrobromide (Dex), chlorphenamine hydrogen maleate (Chl), pseudoephedrine hydrochloride (Pse) and paracetamol (Par) based on flow injection-capillary electrophoresis (FI-CE) analysis with head-column field-amplified sample stacking and large-volume sample stacking was developed. The background electrolyte (BGE) was a solution composed of 55 mM borate-15% (v/v) acetonitrile (ACN) (pH 9.3). The sample was injected electrokinetically between plugs of water. Under the optimum conditions, about a 30-fold improvement in the concentration sensitivity relative to normal CE methods was achieved, giving low limits of detection (LOD) of 1.94 × 10^-5, 0.64 × 10^-5, 1.16 × 10^-5 and 2.84 × 10^-5 mg/mL for Dex, Chl, Pse and Par, respectively. The repeatability (defined as RSD) was 1.01, 1.91, 0.89 and 0.92% with the peak-area evaluation and 1.94, 3.98, 2.66 and 3.27% with the peak-height evaluation for Dex, Chl, Pse and Par, respectively. This method has been successfully applied to the analysis of commercial pharmaceutical preparations containing Dex, Chl, Pse and Par.

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Electrocatalytic oxidation of ascorbic acid (AA) at a carbon paste electrode, chemically modified 2,2′-[3,6-dioxa-1,8-octanediylbis(nitriloethylidyne)]-bis-hydroquinone, was thoroughly investigated. The results of cyclic voltammetry, double potential-step chronoamperometry, linear sweep voltammetry and differential pulse voltammetry (DPV) studies were used for the prediction of the mechanism of electrochemical oxidation of AA mediated with 2,2′-[3,6-dioxa-1,8-octanediylbis(nitriloethylidyne)]-bis-hydroquinone at the surface of the modified electrode. The diffusion coefficient (D = 2.45 × 10^-5 cm² s^-1) and the kinetic parameters such as the electron transfer coefficient (α = 0.34) were also determined. The results of DPV using the 2,2′-[3,6-dioxa-1,8-octanediylbis(nitriloethylidyne)]-bis-hydroquinone-modified electrode were applied in a highly sensitive determination of AA in drug samples. A linear range of 3.0 × 10^-6 - 1.2 × 10^-4 M and the detection limit (3σ) 3.8 × 10^-7 M were obtained for DPV determination of AA in buffered pH 7.00 solutions (0.1 M phosphate buffer).

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A novel chitosan derivative has been synthesized by the condensation of a binucleating ligand, 2,6-bis[(N-methylpiperazine-1-yl)methyl]-4-formylphenol (BNL), with chitosan (CTS). The resulting material (CTS-BNL) was characterized and its adsorption properties towards copper(II) ions in aqueous solutions of various pH have been studied, the adsorption capacity (Q_e) is about 0.94 mmol g^-1 at pH 6 and 1.45 mmol g^-1 at pH 8.5. This higher adsorption capacity may be due to the binucleating ligand anchored to chitosan.

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In order to determine low levels of Cd in urine samples, we tried to remove Mo interference using ICP-MS with a dynamic reaction-cell technique, but failed due to the low sensitivity and the variance with the standards. We then performed solid-phase extraction (SPE) before the ICP-MS measurement. A commercially available chelating resin, NOBIAS PA-1, was used for SPE, and could effectively remove Mo from urine samples, permitting the accurate determination of Cd by ICP-MS. This SPE-ICP-MS method gave 0.012 µg Cd L^-1 as the method limit of quantification, and the mean recovery of Cd spiked with 0.0505 and 5.05 µg L^-1 was 93.1 and 97.6%, respectively.

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Titanium dioxide was used as a photocatalyst to decompose interfering substances for a quantitative analysis of a fungicide (iprodione) in dry basil by HPLC. A quartz vial containing basil extract and titanium dioxide was irradiated with black light. The interfering substances were almost completely decomposed by 180 min of irradiation, whereas 88.3% of iprodione remained. The recovery of iprodione was 102.6% by the proposed method in basil extracts. This may have been due to different decomposition rates of the analyte and interfering substances.

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A newly synthesized substrate, 3-hydroxybutyrylglycyl-glycyl-glycine (3HB-GGG), was applied to the assay of ACE-inhibiting activity to overcome the smaller selectivity and sensitivity of the conventional method. In this study, an ACE-inhibiting assay was improved by the use of a water-soluble tetrazolium salt, 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate sodium salt (WST-1), for the detection of 3-hydroxybutyrate, derived from 3HB-GGG. The optimized conditions were as follows: 0.333 mM NAD⁺, 0.333 mM WST-1, 0.1 mM EDTA, 0.633 U ml^-1 diaphorase, and 0.700 U ml^-1 3-hydroxybutyrate dehydrogenase. The developed assay was efficiently applicable to evaluate the ACE-inhibiting activity of practical ACE inhibitors.

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In the dye-binding method, the absorbance increase caused by a protein error of a pH indicator is observed only in a restricted pH range. However, this pH range in the presence of a detergent has not yet been examined. Thus, the author investigated the pH (pH_UL) where the absorbance increase becomes zero by a calculation based on the chemical equilibrium of a protein error of a pH indicator, and by experiments using four sulfonephthalein dyes. The pH_UL value changed only with the detergent concentration, but did not change at all due to the dye, buffer solution or protein concentrations. Although the pH_UL value was different according to the kind of dye used, it correlated well with the pK_D values (dissociation constant) of BPB, BCG, BCP and BTB. The characteristics of pH_UL in the reactions of the four dyes indicated good agreement with that obtained by a calculation.

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