Nobutoshi Kiba

Simultaneous determination of fluorine, chlorine and bromine in cement with ion chromatography after pyrolysis

A rapid method for simultaneous determination of fluorine, chlorine and bromine in cement with ion chromatography after pyrolysis was proposed for routine quality control analysis. The elements were separated from cement sample by pyrolysis, and were subsequently determined with ion chromatography. A pyrolysis method was investigated for the separation of micro amounts of these elements from cement. Total time taken to determine these elements is about 45 min including 25 min for the pyrolysis and 18 min for ion chromatography. The results of recovery tests ranged 95% or above. The limits of detection for F, Cl and Br are 0.2, 0.3 and 0.5 mg kg(-1), respectively. The method was successfully applied to the simultaneous determination of F, Cl and Br in commercial ordinary Portland cements.

Flow-injection system for the fluorimetric determination of fructose with an immobilized mannitol dehydrogenase reactor

Abstract Immobilized mannitol dehydrogenase is used for the determination of D-fructose in a flow-injection system. The enzyme is immobilized on poly(vinyl alcohol) beads. The oxidation of NADH occurs simultaneously and the disappearance of NADH is measured fluorimetrically. The response is linearly related to fructose concentration in the range 6–600 μM; 30 samples per hour can be analysed. The immobilized enzyme retains over 80% of its initial activity after repetitive use for 2 months.

Enthalpimetry with catalytic reactions-I determination of sulphide solution by the iodine-azide reaction.

Sulphide in the range 0.02-0.5 mumole is determined by direct injection enthalpimetry with relative errors and coefficient of variation within 3%.

Chemiluminometric method for the determination of glycerol in wine by flow-injection analysis with co-immobilized glycerol dehydrogenase/NADH oxidase

A flow-injection method for the determination of glycerol in wine is described. Glycerol dehydrogenase and NADH oxidase were co-immobilized on poly (vinyl alcohol) beads and incorporated in a flow-injection system. The hydrogen peroxide produced was detected chemiluminometrically via a luminol-hexacyanoferrate (III) reaction. Wine was diluted 1000-fold with water and sample solution (50 microl) was injected into the carrier stream. The calibration graph was linear in the range 3 x 10(-7)-3 x 10(-4) M; the detection limit was 7 x 10(-8) M and the sample throughout was 30 h(-1) without carryover.

Enthalpimetry with catalytic reactions—II: Determination of thioureas by the iodine—azide reaction after thin-layer chromatographic separation

A enthalpimetric method for the determination of thiourea and its N-alkyl derivatives (1,3-dimethyl, 1,3-diethyl and 1,3-di-n-butyl), based on thei.

Simultaneous determination of glucose and 1-deoxyglucose in serum by anion-exchange chromatography with an immobilized pyranose oxidase reactor

A liquid chromatographic system for the determination of glucose and 1-deoxyglucose in serum using an immobilized pyranose oxidase reactor and chemiluminescence detection is described. Separation was achieved on a TSK gel SAX column (2 cm x 4 mm I.D.) with an eluent of 0.1 M sodium hydroxide solution. Serum was diluted 30-fold with 0.1 M NaOH. Sample solution (50 microliters) was injected into the system. The hydrogen peroxide produced was detected by measuring the chemiluminescence emitted on admixing with luminol and potassium hexacyanoferrate (III). The calibration graphs were linear from 1 to 600 microM glucose and from 0.6 to 400 microM 1-deoxyglucose; the detection limits for glucose and 1-deoxyglucose were 0.5 and 0.3 microM, respectively. The sample throughput was 10/h. The immobilized enzyme reactor was stable for at least 2 months.

Poly(allylamine) beads as selective sorbent for preconcentration of formaldehyde and acetaldehyde in high-performance liquid chromatographic analysis

Formaldehyde and acetaldehyde in water were determined by preconcentration with poly(allylamine) beads, derivatization with 2,4-dinitrophenylhydrazine (DPH) and analysis by HPLC. Poly(allylamine) beads (0.5 g) were used to adsorb formaldehyde and acetaldehyde at 1.2-150 microg l(-1) and 3.5-220 microg l(-1) from water (1 l). The concentration factor is 50 fold. The aldehydes were eluted and derivatized with 2 mM DPH in 0.5 M H2SO4 (10 ml). The time of analysis was 1 h. The detection limits (S/N=3) for formaldehyde and acetaldehyde were 0.6 and 2 microg l(-1), respectively.

Determination of branched-chain L-amino acids by flow-injection analysis with co-immobilized leucine dehydrogenase/NADH oxidase and chemiluminescence detection

Abstract A method for the determination of branched-chain L-amino acids in plasma is described. Leucine dehydrogenase and NADH oxidase were co-immobilized on aminated poly(vinyl alcohol) beads and incorporated in a flow-injection system with chemiluminescence detection. 20 μ1 sample solution was injected into the system. The hydrogen peroxide produced was detected chemiluminometrically via a luminol-hexacyanoferrate(III) reaction. The calibration graph was linear for 5 × 10 −7 -6 × 10 −4 M; the detection limit (signal-to-noise ratio = 3) was 3 × 10 −7 M and the sample throughput was 15 h −1 without carryover.

Flow-injection determination of glucose in serum with an immobilized pyranose oxidase reactor

Abstract A flow-injection system for the chemiluminometric determination of d -glucose in serum with an immobilized pyranose oxidase reactor is described. Pyranose oxidase is immobilized on controled-pore glass beads and packed into a stainless-steel column. Serum (100 nl) is diluted 1000-fold with water. Sample solution (10 μl) is injected into the carrier stream. The hydrogen peroxide is detected by measuring the chemiluminescence emitted on admixing with luminol and potassium hexacyanoferrate(III). The maximum sample throughput is 60 h −1 . The calibration graph is linear from 0.2 to 500 μM glucose; the detection limit is 0.05 μM. The immobilized enzyme reactor is stable for at least 2 months.

Determination of glycerol, 1,2-propanediol and triglycerides by high-performance liquid chromatography and a post-column reactor containing immobilized glycerol dehydrogenase

Abstract A fluorimetri method is described for the determination of glycerol, 1,2-propanediol and triglycerides in serum by high-performance liquid chromatography with an on-line post-column reactor containing immobilized glycerol dehydrogenase. Before separation, triglycerides are cleaved with lipase and esterase. The polyhydric alcohols are separated from each other on a Finepak SIL C18 (10 μm) column with water as eluent. The NADHI produced from the enzymatic reaction is monitored by fluorimetry. Calibration curves are linear between 0.01 mM and 1.0 mM for glycerol or 2.0 mM for 1,2-propanediol. The method gave satisfactory results for control sera.