Vol. 55 No. 3
March, 2006
Masami Shibukawa1
1 Department of Applied Molecular Chemistry, College of Industrial Technology, Nihon University, 1-2-1, Izumi-cho, Narashino-shi, Chiba 275-8575(Received 5 September 2005, Accepted 24 November 2005)
The states of water incorporated in a cross-linked dextran (Sephadex G-10, G-15), polyacrylamide (Bio-Gel P-2, P-4), a polyethylene glycol (TSKgel Ether-250), cross-linked poly(vinyl alcohol) (Toyopearl HW-40S, 50S, 55S, and 75S), and polystyrene-divinylbenzene copolymer gel packings (TSKgel Styrene-60 and Styrene-250) were investigated by means of differential scanning calorimetry. It was found that there were three types of water in these gels; non-freezing water, intermediate or freezable bound water and free or bulk water. The amount of water that functions as the stationary phase in the column packed with the each gel was also estimated by a liquid chromatographic method. The estimated amount of the stationary phase water is in good agreement with the sum of the amount of non-freezing water and that of intermediate water for Sephadex G-10, G-15, Bio-Gel P-2, P-4, and Toyopearl HW-40S, 50S, 55S, while it agrees with the amount of only non-freezing water for TSKgel Ether-250 and Toyopearl HW-75S. This means that the stationary phase water consists of non-freezing water and freezable bound water for the former hydrophilic polymer gels, while only non-freezing water functions as the stationary phase in the latter two gels. On the other hand, no water in the polystyrene-divinylbenzene copolymer gels functioned as the stationary phase. This result can be attributed to the differences in the affinity of the polymer matrix for water molecules and in the structure of the gels; the hydrophilic polymer gels containing a polymer matrix at relatively high concentrations have a homogeneous gel phase, whereas the others have a heterogeneous gel phase consisting of hydrated polymer domains and macropores with a relatively hydrophobic surface. The freezable bound water in Toyopearl HW-75S and TSKgel Ether-250 as well as that in TSKgel Styrene-250 may be water isolated in pores of the hydrophobic domains.
Keywords : states of water; liquid chromatography; differential scanning calorimetry; polymer gel packings; separation selectivity.
Kunihiro Watanabe1, Yusaku Ogawa1, Masayuki Itagaki1 and Kazuyasu Tokiwa2
1 Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641, Yamazaki, Noda-shi, Chiba 278-8510(Received 10 March 2005, Accepted 13 December 2005)
The determination of the average valence of thallium in a high-Tc superconductor was investigated by capillary electrophoresis. The amount of sample required was decreased from 5~7 mg to 0.2 mg by a procedure developed in this investigation. As the thallium(I) aqua ion, itself, absorbed in the UV domain, the ion was measured directly at 215 nm after migration as a cation at 25 kV. The shorter migration time enhanced the precision. Therefore, the applied voltage was selected to be 25 kV at a migration time of 3 min. The sample solution was injected in the capillary by the hydrodynamic method. A 10 nl portior of sample was introduced based on the siphon principle by injection for 900 s. A calibration curve, which was linear at 0~10 ppm, was obtained under the optimal conditions. On the other hand, thallium(III) was detected at 242 nm as an anion in the presence of a large amount of chloride ions. The applied voltage on the thallium(III) was -30 kV using a migration solution (pH buffer solution) adjusted at pH 2.25. Then, the migration time was 7 min. The calibration curve for thallium (III) obtained from the peak area was linear at a concentration below 250 ppm. A simultaneous composition analysis of the thallium system superconductor was performed by an indirect detection method after the addition of imidazole into the migration solution. Ca2+, Ba2+, and Cu2+ were separated at 12 min and determined at 210 nm. The compositions of two kinds of sample examined were 1 : 2 : 2 : 3 (Tl : Ba : Ca : Cu) and 1 : 2 : 4 : 5. The average valences (2.97 and 2.95) of thallium in superconductors could be calculated according to the following equation: n=3-{2[Tl+/Total Tl]}. The results agreed well with those obtained by iodometry as a conventional method. The total sample amount required in this method was 0.2 mg for Tl(I) and Tl(III), which was dissolved in 0.5 ml of 0.01 M HCl.
Keywords : average valence of thallium; capillary electrophoresis; superconductor; simultaneous determination; indirect detection.
Yasutada Suzuki1, Jiye Jin2, Kei Arisawa1, Susumu Kawakubo1 and Masaaki Iwatsuki1
1 Department of Applied Chemistry, Interdisciplinary School of Medicine and Engineering, University of Yamanashi, 4-3-11, Takeda, Kofu-shi, Yamanashi 400-8511(Received 21 October 2005, Accepted 13 December 2005)
A palmtop-size coulometric titrator based on the photometric detection principle was developed for determining the peroxide value (POV) in samples of edible oil. The circuit for electrolysis was composed of a voltage booster that could generate +30 V from +5 V of a power source, while a circuit for constant-current control was fabricated using a junction-type field-effect transistor (JFET), which could supply a current of 0 to 2 mA. In this titrator, a photometric cell with a 2-cm optical path length served as an electrolysis compartment containing a generator electrode. The end point of titration was determined photometrically by monitoring the absorbance of the electrolytic solution during the electrolysis with a home-made colorimeter using an ultra-violet light-emitting diode (UV-LED, emission wavelength 370 nm) as a light source and two photodiodes (PDs) as detectors. The data corresponding to the absorbance, elapsed electrolysis time, and the electrolysis current were collected by an external PC via a serial interface built in the controller. It was demonstrated that the titrator could provide good accuracy and precision in the standardization of a sodium thiosulfate solution. Finally, the device was applied to the determination of POVs in samples of edible oil; the analytical results were in good agreement with those determined by iodometry. Moreover, the titrator showed a capability for the determination of some colored samples whose end point was hardly determined by conventional iodometry. The advantages of versatility, accuracy as well as sensitivity in end point detection make the device attractive for the determination of POVs in many practical samples.
Keywords : peroxide value; iodometry; coulometric/photometric titration; palmtop-size.
Chihiro Yoshioka1, Hiroshi Suzuki1, Masako Ishikawa1, Takefumi Yokokura1 and Toshihiro Shirasaki1
1 Naka Application Center, Hitachi High-Technologies Corporation, 11-1, Ishikawa-cho, Hitachinaka-shi, Ibaraki 312-0057(Received 29 September 2005, Accepted 6 December 2005)
By using high-performance liquid chromatograph, a simultaneous analysis method for glyphosate and its major metabolite amiomethylphosphonic acid (AMPA) in river water and tap water was investigated. Separation was performed by an anione-exchange column. Detection was carried out by a using fluorescent o-phthalaldehyde postcolumn reagent. In this method, glyphosate was reacted with a sodium hypochlorite solution to form a primary amine and it was determined by HPLC with a fluorescence detection after reacting with o-phthalaldehyde. In AMPA, since a reaction with sodium hypochlorite solution reduces the sensitivity, a sodium hypochlorite solution was not added. This led to an improved sensitivity of 12-times higher than in the case where sodium hypochlorite solution was added. In the repeated measurements (n=6) of 20 µg/l glyphosate and AMPA, the relative standard deviation was 1% and below, which indicates a satisfactory result. The detection limits (S/N=3) were 0.13 µg/l for glyphosate and 0.19 µg/l for AMPA, respectively. The recovery of these compounds in river water and tap water was 96~102%. These results show that the simultaneous analysis method using high-performance liquid chromatograph can be applied to these analyses.
Keywords : glyphosate; aminomethlphosphonic acid; postcolumn; sodium hypochlorite solution; SFR method.
Nobuo Uehara1, Kazutomo Nomoto1 and Tokuo Shimizu1
1 Graduate School of Engineering Utsunomiya University, 7-1-2, Yoto, Utsunomiya-shi, Tochigi 321-8585(Received 23 July 2005, Accepted 24 November 2005)
The solvolytic dissociation kinetics of the oxine-copper complex {bis(8-quinolinolato)copper(II)} was studied with a reversed-phase high-performance liquid chromatography and spectrophotometry. The analysis of the chromatographic peak height of the complex, which decreased with a decrement of the flow rate of the eluent {water-acetonitrile (70 : 30 wt%)}, gave an apparent rate constant kd of 1.4±0.5×10-4 s-1 for the dissociation reaction. With the spectrophotometric method, the apparent rate constant kex of the ligand exchange with EDTA was determined to be 0.75±0.11 s-1. The observed small value of kd, compared to the value of kex, can be attributed to the difference of mechanisms between the ligand-exchange reaction and the solvolytic dissociation. The value of kex is controlled by the concentration of EDTA, indicating that EDTA was involved with the rate-determining step of the ligand-exchange reaction. On the other hand, the solvolytic dissociation of the oxine-copper complex is induced by a lack of 8-quinolinol around complex.
Keywords : oxine-copper; solvolytic dissociation rate constant; ligand exchange reaction rate constant; high performance liquid chromatography.
Hisashi Maruko1, Hiroshi Sekiguchi1, Yasuo Seto1 and Akiyoshi Sato2
1 National Research Institute of Police Science, 6-3-1, Kashiwanoha, Kashiwa-shi, Chiba 277-0882(Received 14 October 2005, Accepted 6 December 2005)
The detection performance of a portable aspiration-type ion mobility spectrometer (ChemPro100, Environics) was investigated with nerve gases, blister agents, blood agents and related compounds. The vapors of sarin, soman, tabun were recognized as “Nerve (nerve gas)” after about 10~20 s sampling, and the detection limits were below 0.1 mg/m3. The vapors of mustard gas and lewisite 1 were recognized as “Blister (blister agent)” after about 10~20 s sampling, and the detection limits were several mg/m3. The gases of hydrogen cyanide and cyanogen chloride were not recognized as “Blood (blood agent)”. The vapors of nerve gas simulants, such as dimethylmethylphosphonate and N,N-dimethylformamide, were recognized as “Nerve”, and the vapors of blister agent simulants, such as 2-chloroethylethylsulfide, ethanol, toluence and chloroform, were recognized as “Blister”. The other solvents were recognized as “Unknown chemical”.
Keywords : chemical warfare agents; on-site detector; detection performance; ion mobility spectrometer.
Tomoe Nishino1, Tetsufumi Harusue1 and Masaaki Maruyama1
1 Chemicals Evaluation and Research Institute, Japan, 1600, Shimo-Takano, Sugito-machi, Kitakatsushika-gun, Saitama 345-0043(Received 24 October 2005, Accepted 13 December 2005)
When a gas standard mixture is consumed, the pressure in its cylinder is reduced. We studied how much this affects the concentrations of the gas standard mixtures. We prepared VOCs (Volatile Organic Compaunds) gas standard mixtures (100 vol ppb), and analyzed their concentrations at 10, 8, 6, 4, 2, 1 MPa each by GC-FID. As a result, the concentrations were not changed in 3 components (dichloromethane, 1,3-butadiene, vinyl chloride). However, the concentrations increased with the consumption in 5 components (benzene, chloroform, 1,2-dichloroethane, trichloroethylene, tetrachloroethylene). 1,2-dichloroethane had the largest increase, and its concentrations in 1 MPa was 3% higher than that in 10 MPa. Therefore the pressure should be checked when using a gas standard mixture. Also, it should be renewed if necessary.
Keywords : gas standard mixtures; concentrations; VOCs.
Hitoshi Okamoto
Analytical Laboratory, Self Medication Laboratories, Taisho Pharmaceutical Co. Ltd., 1-403, Yoshino-cho, Kita-ku, Saitama-shi, Saitama 331-9530
(Awarded by Niigata University of Pharmacy and Applied Life Science dated March 18, 2005)
In this thesis, simultaneous determination methods for ingredients in pharmaceutical preparations were studied by capillary electrophoresis (CE). A following study involved applications of an in-capillary enzyme reaction to pharmaceutical analyses. The author studied it while considering that the new method will become a standard analytical procedure for pharmaceuticals of the next generation. First, several separation modes of CE were applied for each dosage form. That is, micellar electrokinetic chromatography (MEKC), cyclodextrin-modified MEKC, hydrophobic interaction electrokinetic chromatography, and cyclodextrin-modified microemulsion electrokinetic chromatography were applied to a vitamin-enriched drink, ophthalmic solutions, an ointment, and cold medicine, respectively. Next, the in-capillary enzyme reaction method was applied to pharmaceutical analysis for the first time. The method was used to determine riboflavin phosphate in a vitamin-enriched drink based on its conversion to riboflavin with alkaline phosphatase. It was then also applied to determine the total amount of chondroitin sulfate based on its conversion to desulfated chondro-disaccharide with chondroitinase ABC and chondrosulfatases. Finally, a scheme for the selection of the CE separation mode of every dosage form was proposed. Several applications and in-capillary enzyme reaction techniques presented in this thesis gave encouraging results in pharmaceutical analysis.
(Received November 16, 2005)
Keywords : capillary electrophoresis; micellar electrokinetic chromatography; cyclodextrin-modified micellar electrokinetic chromatography; hydrophobic interaction electrokinetic chromatography; cyclodextrin-modified microemulsion electrokinetic chromatography; in-capillary enzyme reaction; pharmaceutical analysis.
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