Vol. 50 No. 9
September, 2001
Jun-ichi Anzai*
* Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578
(Received 11 July 2001)The development of polyelectrolyte multilayer films (PEM) is reviewed in relation to their applications to analytical chemistry. PEMs are constructed by a layer-by-layer deposition of oppositely charged polyelectrolytes on a solid surface from aqueous solutions. The PEM films are formed through an electrostatic force of attraction between polycation and polyanion. The structure of PEM films depends significantly on the properties of the bathing solution, including the concentration of polyelectrolytes, ionic strength, and pH. High ionic strength solutions usually result in thicker film. It is known that hydrogen bonding and hydrophobic interactions also play a role as a secondary force in addition to the electrostatic interactions. Functional PEMs have been prepared using charged dyes, metal and inorganic particles, DNA, proteins, and virus. Analytical applications of PEM include coating the inner wall of capillaries for electrophoretic separation, pervaporation films for alcohol/water purification, sensitive layers of gas and humidity sensors, surface modification of functional electrodes, and ion-sensitive PEMs for optical ion sensors. Protein-containing PEMs are finding wide applications to immuno sensors, enzyme sensors, bioreactors, and bio-fuel cells, in which proteins are still active in the PEM films.
Keywords : polyelectrolyte multilayer film; layer-by-layer deposition; thin film, dye film; protein film; separation and purification.
Toshihiro Shirasaki*, Isao Nishino** and Kazuko Yamamoto*
*Hitachi Science Systems, Ltd., 882, Ichige, Hitachinaka-shi, Ibaraki 312-8504
**Nishinihon Technology Consultant Co., Ltd., 649, Yabase, Kusatsu-shi, Shiga 525-0066
The determination of V, Cr, As, Se and Mo at ultra-trace levels in river and lake-water samples was carried out using a nitrogen microwave-induced plasma mass spectrometer (N2MIP-MS). Spectral interferences caused by a matrix, such as Na, Ca, Cl, P and S, were examined. As a results, the 14N223Na+ ion was produced at m/z=51 in the mass spectrum, which interfered with a measurement of vanadium. However, it was found that the 14N223Na+ ion intensity decreased with an increase in the microwave power of the nitrogen plasma. Therefore, the microwave power was set to be 1.3 kW. Vanadium in river and lake-water samples was able to be determined after the samples were only diluted by 5-10 fold with pure water. The proposed method was applied to the determination of V, Cr, As, Se and Mo in standard reference materials (River Water Reference Material for Trace metals; NRC·CNRC SLRS-4, Certified Reference Material of Riverine Water; JAC 0032) and terrestrial water samples. The analytical results of standard reference materials were in good agreement with the certified or reported values. The detection limits (3σ) were 0.3 ng/l for V, 0.2 ng/l for Cr, 8.3 ng/l for As, 26 ng/l for Se and 4.0 ng/l Mo.
Keywords : nitrogen microwave-induced plasma mass spectrometry; determination of vanadium, chromium, arsenic, selenium and molybdenum; spectral interference.
Toshio Yao and Youko Nanjyo**
*Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1, Gakuencho, Sakai-shi, Osaka 599-8531
**
The multilayer immobilization of enzyme molecules onto controlled-pore glass (CPG) was carried out stepwise by the alternating and repeated binding of avidin and biotin-labeled enzymes on a monolayer of biotin-labeled enzymes or avidin crosslinked with glutaraldehyde onto aminopropyl-CPG (NH2-CPG) with an average pore size of 53.0 nm. This technique was applied to the preparation of enzyme minireactors with immobilized glucose oxidase (GOD) or alcohol oxidase (AOD) and co-immobilized GOD/β-galactosidase (Gal) or GOD/peroxidase (POD), and the layer-by-layer structure of enzyme molecules immobilized into the pore space of CPG was schematically estimated from the geometry of the enzyme molecules and the immobilized amounts of avidin and biotin-labeled enzymes. In the first step of the immobilization, the cross-linking with glutaraldehyde of enzymes onto the CPG was almost constant (4 nmol/10 mg NH2-CPG) in the immobilized amounts for each of avidin, GOD, and AOD, the molecular weight of which was below 300000. Furthermore, the alternating immobilization of avidin or biotin-labeled enzymes resulted in a layer-by-layer structure of 1:1 in the number of moles of the same and different enzymes. However, the immobilized amount of the larger Gal molecule (Mw≈540000) was less than that of GOD or AOD, because of a steric hindrance in the pore space. In this paper, an optimum design of enzyme minireactors based on the layer-by-layer immobilization technique is discussed based on the geometrical differences of enzyme molecules.
Keywords : enzyme reactor; controlled-pore glass; multilayer immobilization of enzyme; avidin; biotin-labeled enzyme.
Toshio Yao and Youko Nanjyo**
*Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1, Gakuencho, Sakai-shi, Osaka 599-8531
**
To prepare an enzyme minireactor involving amplification for L-glutamate, multilayer co-immobilization of L-glutamate oxidase (GlOD) and glutamate dehydrogenase (GlDH) onto aminopropyl controlled-pore glass (NH2-CPG) was carried out stepwise by the alternating binding of avidin and biotin-labeled enzymes. Amplification for L-glutamate is based on substrate recycling between coupled enzymes. The layer-by-layer structure of enzyme molecules immobilized into the pore-space of CPG was geometrically estimated from the immobilized amounts of avidin and biotin-labeled enzymes. The enzyme reactor with a greatest amplification was obtained by the alternating binding of avidin and biotin-labeled enzymes on a monolayer of biotin-labeled GlOD and GlDH crosslinked randomly with glutaraldehyde onto the NH2-CPG; the amplification factor for L-glutamate was 606 at a flow rate of 20 µl min-1, when a 0.1 M ammonium phosphate buffer (pH 7.5) containing 0.75 mM NADPH and 1 mM sodium azide was used as the carrier buffer in a FIA system. The calibration graph for the amplified response was linear over the range 5×10-9~5×10-7 M L-glutamate for 10 µl injections. The detection limit was 3×10-9 M (30 fmol) for L-glutamate.
Keywords : enzyme reactor; amplification; L-glutamate; multilayer immobilization of enzyme; biotin-avidin binding.
Masato Ueda, Naoko Sakaki, Takayo Moriuchi-Kawakami and Yasuhiko Shibutani*
*Applied Chemistry, Osaka Institute of Technology, 5-16-1, Omiya, Asahi-ku, Osaka 535-8585
(Received 29 June 2001, Accepted 17 August 2001)To examine the functionality as an Ag+ neutral carrier of a dioxime-type Schiff base easily obtained by coupling the dyad monoxime to the diamine, several kinds of Schiff bases were synthesized using the diamine of which the different alkyl chain lengths, and Ag+ ion selectivities for the obtained Schiff bases were evaluated by potentiometry. Among the Schiff bases tested here, N,N'-bis(2'-hydroxyimino-1'-phenyl-propylidene)-1,3-propanediamine, PHO3, derived from α-Isonitrosopropiophenone and 1,3-Diaminopropane was found to be the most excellent Ag+ neutral carrier. That is, the PHO3-NPOE (plasticizer)-KTpClPB (anion excluder) system PVC membrane electrode gave good results with a Nernstian response (59 mV decade-1) in accordance with the wide Ag+ activity change in the activity range 10-6.3 M~10-1.1 M. The Ag+ ion selectivity with respect to K+ ion -log kpotAg,k was 3.35 (fixed interference method, FIM). In addition, when the practical performance, such as the response time, potential stability and lifetime for the PHO3-NPOE-KTpClPB system electrode was examined, the functionality of PHO3 derivative as the Ag+ neutral carrier was comparable to that of the conventional Ag+ neutral carrier.
Keywords : dioxime-type Schiff base; silver-ion selective electrode; PVC membrane; selectivity coefficient; ESCA spectral data.
Norio Katoh*
*Research Institute, Ishikawajimaharima Heavy Industries Co., Ltd., 3-1-15, Toyosu, Koutou-ku, Tokyo 135-8732
(Received 29 June 2001, Accepted 18 July 2001)According to the present JIS method, which describes the determination of ammonia(NH3) in flue gas, the presence of more than 10 times as much sulfur dioxide(SO2) as NH3 results in interference with the determination of NH3 by indophenol blue absorptiometry. The magnitude of interference from the coexisting sulfur dioxide and its elimination of described. The magnitude of interference was investigated using NH3 and SO2 standard gases. Both standard gases were bubbled through a 0.5% boric acid solution independently and simultaneously; 0~200 times as much SO2 as NH3 by mole was bubbled through a boric acid solution. The absorbed NH3 and SO2 were determined by coulometry and alkalimetry, respectively. The magnitude of interference was dependent upon the amount of SO2 absorbed in the boric acid solution, not the molar ratio of SO2 to NH3. More than 100 µmol SO2 led to a serious decrease in the absorbance. In the case of a 20 liter sample, it was found that more than approximately 110 volppm of SO2 gave a lower analytical value of NH3. The interference could be eliminated by bubbling 400 ml of oxygen at a flow rate of about 70 ml min-1 through a boric acid solution containing the absorbed gas sample.
Keywords : ammonia; sulfur dioxide; indophenol blue absorptiometry; exhaust gases; gas analysis.
Hideo Hayashi, Yasuhisa Hara, Tomokazu Tanaka and Masataka Hiraide*
*Department of Molecular Design and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603
(Received 24 May 2001, Accepted 17 August 2001)Although ICP-MS offers a powerful multielement analytical method, the argon gas severely interferes with the determination of iron because of the formation of large background spectra. A combined method of electrothermal vaporization (ETV) and low-pressure helium-ICP-MS was therefore employed to overcome this problem. Mass spectral interferences, however, still occurred at m/z of 54 and 56, which were assigned to 40Ar14N+ and 40Ar16O+, respectively. We found that the polyatomic interferences were caused by leaks of the ambient air through the glass ETV chamber. In the present work, the chamber was newly designed and constructed from aluminum with specially prepared vacuum parts. A 5 µl volume of the sample was placed on a tungsten filament and heated at 2.6 A for 100 s to remove the solvent. After evacuating the chamber to 5 torr, the filament was heated to 2500°C by the discharge of a high-capacity condenser (0.27 F) for evaporating the sample. The resulting plume was transported to the plasma torch with a stream of carrier gas for the determination of the most abundant isotope, 56Fe+. The relative standard deviation for the signal intensity (50 pg of Fe, n=9) was approximately 13%. The detection limit based on 3σ was 0.8 ng ml-1, which was 25-times lower compared with the conventional argon ICP-MS.
Keywords : low-pressure helium ICP-MS; electrothermal vaporization; iron; spectral interference; microsamples.
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