This review outlines the current situation and views the future analysis of hazardous chemicals in the environment by capillary electrophoresis (CE). A brief introduction of CE, the current state and problems concerning the analysis of hazardous chemicals in the environment are described for the first time. CE has a higher separation efficiency than that of LC, and a better suitability for the analysis of non-volatile or thermally degradable substances than with GC. Two modes of CE, capillary zone electrophoresis (CZE) and electrokinetic chromatography (EKC), are mainly used for their analysis. EKC has more applications than CZE because of the separation ability of electrically neutral analytes. Examples of the optimization of hazardous chemical separation and determination in real samples by CE are given. Phenols and polycyclic aromatic hydrocarbons (PAHs) are mainly described, because there are relatively many applications of these chemicals. An isomeric separation of phenols was easily achieved by CE. Micellar EKC (MEKC) or the addition of cyclodextrin (CD) was effective for their separation. For PAHs, the addition of CD and/or organic solvents was investigated because of their hydrophobicity. Applications to other hazardous chemicals, such as dioxins, polychlorobiphenyls, nitro- and amino-aromatics, aromatic sulfonates, dyes and surfactants were described. Regarding an improvement of CE for environmental analysis, the techniques of sensitivity enhancement and the connections to mass spectrometry (MS) that have been developed to date are is discussed introduced. The combined use of off-line pre-concentration methods. Solid-phase extraction methods have been mainly used for environmental analysis. On-line concentration methods suitable for CE have been developed. Stacking or field-amplified injection has been used in both CZE and EKC. Sweeping can be used only in EKC and a higher concentration has been achieved for hydrophobic compounds. For sensitive detection, laser-induced fluorescence detection and electrochemical detection have frequently been applied to CE. The connection with MS is necessary to identifity of unknown compounds. Although electrospray ionization has mainly been used for this connection, the applications of atmospheric pressure chemical ionization, frit-fast atom bombardment ionization and electron ionization have been investigated because of a larger tolerance of the presence of salts and/or a higher ionization efficiency. Finally, the expectations of CE as a high-performance analytical method of hazardous chemicals in the future are briefly described.

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Measurements selective toward tetracaine were performed using a surface plasmon resonance (SPR) sensor with the sensor chip coated with a tetracaine-selective film prepared by a molecular imprinting technique. For preparing the tetracaine-selective film, tetracaine was used as a template, methacrylic acid as a functional monomer; ethyleneglycol dimethacrylate as a crosslinking monomer and 2,2'-azobisisobutyronitrile as an initiator. The quantity of tetracaine caught by the tetracaine-selective film was 0.42 ng/mm² using the SPR measurement. The rate at which the tetracaine was caught by the tetracaine-selective film versus the tetracaine concentration gave a linear plot in the range of 0.01 to 0.04 mol/l, which means that this method is applicable to quantitative analysis. The tetracaine-selective film was applied to other local anesthetics, such as procaine, lidcaine, mepivacaine and bupivacaine. The quantities of these anesthetics caught by the tetracaine-selective film were sufficiently smaller than 0.42 ng/mm². Thus, a prepared SPR sensor with a tetracaine-selective film had high selectivity toward tetracaine.

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The spectrophotometric determination of trace amounts of iron and cobalt was investigated for flow injection analysis. Cationic or polarized metal chelates were concentrated on a Teflon surface, which was treated with a 2 M NaOH solution for 3 hours. Then, the metal chelates adsorbed in the Teflon capillary tube were eluted with a solvent mixture of ethanol and 0.1 M HNO₃, and determined by on-line by spectrophotometry. Cobalt (III) reacted with tridentate ligands to form stable chelate complexes, which have cationic charge in the complexes. 2-(5-Bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]aniline, sodium salt (5-Br-PSAA) and 1-(2-pyridylazo)-2-naphtol (PAN) were used to form cationic complexes as tridentate and mono valence ligands. The composition of the complexes obtained under the standard conditions was metal : ligand=1 : 2. The metal complexes were concentrated for 10 min with 2.9 ml/min as the flow rate of the sample solution. As a result, the apparent molar absorption coefficients of the complexes were enhanced to 100 times as compared to each of there molar absorption coefficients. The optimum conditions were as follows: chelate complex preparation pH, 4.7; concentration pH, 8.9; eluent flow rate, 0.7 ml/min; measurement wavelength, 602 nm (Co-5-Br-PSAA), 554 nm (Fe-5-Br-PSAA), and 585 nm (Co-PAN), concentration tube length, 6 m. The cobalt was determined over the range 0.6∼50 ppb with PAN and 0.3∼10 ppb with 5-Br-PSAA; iron (III) was 0.1∼10 ppb with 5-Br-PSAA. The result of determination of iron (III) in tap water showed good agreement with the values obtained by ICP-AES.

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To develop an automated system for determining the concentrations of the components (CaCl₂, MgCl₂, KCl, NaCl) in the mother liquid and the concentrated brine of the salt-manufacturing process, a determination of the concentrations of the mother liquid and the concentrated brine components using the absorbance differences of four pairs of wavenumbers measured by attenuated total-reflectance IR spectrometry has been studied. It is suggested that the concentrations of the components determined by the calibration equation using diluted solutions made by diluting mother-liquid model solutions over a wide temperature range with water are not influenced by the temperatures of the mother liquid and the concentrated brine in the crystallizer. In this study an automated composition-determining system was constructed, and a field test of this system was carried out at Ako Kaisui Co., Ltd. In this field test, all components of the mother-liquid and the concentrated brine were accurately determined for the salt-manufacturing process. Therefore, this system was realized and, after continuously running, the automated system run without any problems for forty hours. The system was therefore considered to be a success.

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The preparation and application of a coated-graphite gallium (III) ion-selective electrode, based on the chlorogallium (III) ion form anion-exchange resin fixed in a poly(vinyl chloride) matrix, are described. The effects of the hydrochloric acid concentration and interference ions were investigated. The electrode showed a near-Nernstian slope of 30±2 mV/decade over a gallium (III) ion concentration range of 10^-6∼10^-2 mol dm^-3 and a response time of 30 s in a 6 mol dm^-3 hydrochloric acid solution. As^III and Al^III do not interfere, but othor ions, such as Cr₂O₇^2-, FeCl₄^-, TeCl₆^2-, ClO₄^- and NO₃^-, cause interference. The electrode was successfully applied to the determination of gallium in gallium arsenide after only its dissolution in 6 mol dm^-3 hydrochloric acid. Gallium in silicon-aluminium alloy was determined by the electrode after the separation of gallium (III) from interference ions and fusion matrices by the ion-exchange method.

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To develop an automated system for determining the concentrations of the components (CaCl₂, MgCl₂, KCl, NaCl) in the mother-liquid and the concentrated brine of the salt-manufacturing process, a procedure for accurately determining the concentration of each component by attenuated total-reflectance IR (ATR-IR) spectrometry and the multiple linear-regression (MLR) method was studied. Many calibration samples are necessary for obtaining significant determined values, because the MLR method requires the number of calibration samples to be more than the number of independent values (the number of pairs of wavenumbers). Therefore, a simple correction method for the calibration matrix of the MLR equation has been investigated. This correction method corrects the absorbance differences of a measured sample by using the absorbance differences of two standard samples. The average values of the mean errors of the determined values after correcting were lower than those in the case of not correcting. Therefore, an automated system for determining the concentrations of the components in the mother-liquid and the concentrated brine of the salt-manufacturing process using the automated calibration system is proposed. This correction method can be applied to other multivariate analyses (PLS method, etc.) and other spectrophotometric analyses (visible, ultraviolet, near infrared, fluorometry, etc.).

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[in Japanese]

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