Hironobu Ohkita

Breath acetone analysis with miniaturized sample preparation device: In-needle preconcentration and subsequent determination by gas chromatography–mass spectroscopy

A new approach to the determination of human breath acetone with particle-packed sample preparation needle was developed. The extraction needle was packed with a copolymer of methacrylic acid and ethylene glycol dimethacrylate as the extraction medium. For the analysis of breath sample, exhaled breath was collected in a sampling bag, and 50 mL of the breath sample was extracted with the needle-type sample preparation device followed by analysis using gas chromatography-mass spectrometry (GC-MS). After the optimization of several basic extraction conditions for standard acetone samples, breath acetone concentration taken from controlled type-2 diabetic patients was determined. Furthermore, time variations of breath and urine acetone of four healthy individuals under fasting conditions were measured. Urine sample was collected in glass vial, and urine acetone concentration was also determined with the extraction needle by analyzing the corresponding headspace gas. The results demonstrated that the particle-packed extraction needle showed an excellent extraction performance for acetone in both breath and urine headspace samples, and that there is a clear correlation between the concentration of breath acetone and HbA1c level of controlled type-2 diabetic patients. The breath acetone level in controlled diabetic patients was in the range between 0.19 and 0.66 ppmv, where its concentration in medically untreated type-2 patient was 0.92 and 1.20 ppmv. The breath acetone concentration in healthy male was increased to 5.66 ppmv under the 24 h of fasting test, and a high correlation between the breath and urine acetone concentration was also observed. On the basis of the above results, the potential applications of the proposed method to the diagnosis of diabetes and/or ketoacidosis were suggested.

Thermal and chemical recycle of waste polymers

Abstract Catalytic degradations of polyethylene into fuel oils and of polystyrene into styrene monomer have been studied using solid acids and bases as catalysts. Solid acids such as silica-aluminas and ZSM-5 zeolite were found to be effective to degrade waste polyethylene into fuel oils, and solid bases such as BaO and K 2 O were concluded to be effective to convert waste polystyrene into styrene monomer. A design of recyclable polystyrene films will be briefly mentioned.

Regiospecific Cp★Ru+ mediated codimerization of conjugated dienes with non-conjugated 1,5-dienes and its application to catalytic cooligomerization

Abstract When Cp★RuCl(η4-butadiene) (1; where Cp★  η5-C5Me5) was treated with an excess of 1,5- hexadiene in the presence of silver trifluoromethanesulfonate (AgOTf) at or below ambient temperature, a 2-(3′-butenyl)- 1,5-hexadiene complex of cationic ruthenium was obtained by regiospecific C4 homologation at the internal carbon atom of the non-conjugated diene. This stoichiometric CC bonding was extended to the catalytic codimerization and stepwise oligomerization of butadiene with 1,5-hexadiene or 1-hexene.

Selective preparation of β-MoO3 and silicomolybdic acid(SMA) on MCM-41 from molybdic acid precursor and their partial oxidation performances

Abstract SMA(Mo/MCM-41Imp) and β-MoO 3 (Mo/MCM-41 Evap) were successfully prepared on MCM-41 using the molybdic acid solution. The molybdic acid solution is the effective precursor to generate selectively either SMA or β-MoO 3, and those species are anchored on MCM-41 through the formation of SMA. The Mo/MCM-41Imp catalyst showed a good catalytic performance for partial oxidation of methane to formaldehyde while the Mo/MCM-41 Evap is a promising catalyst for partial oxidation of methanol to formaldehyde.

Selective Preparation of β- and α-Silicomolybdic Acid and Their Methanol Oxidative Behaviors

Abstractβ-silicomolybdic acid (SMA)/SiO2 was successfully prepared and its catalytic activity in methanol partial oxidation was studied. After catalytic study, β-SMA was transformed into two other types of α-MoO3 that had different Raman relative peaks ratios upon the pre-treatment prior to the reaction. On the other hand, α-SMA/SiO2 was also prepared for comparison. α-SMA was decomposed into surface oxomolybdates species which favored the formation of COx while MoO3 was formed from β-SMA and promoted HCHO formation.Graphical Abstract.

Raman study of the formation of beta silicomolybdic acid supported on silica, prepared by impregnation method

Beta silicomolibdic acid/silica (β-SMA, a metastable form of silicomolybdic acid - H(4)SiMo(12)O(40)) forms by the impregnation of fumed silica into molybdenum solution obtained by hydrolyzation of MoO(2)Cl(2.) β-SMA/silica is found to be stable up to 300 °C after calcination for 1h due to the existence of an interlayer MoO(3) between silica surface and β-SMA. Structures of molybdenum species in the preparation process (including precursor solution) were analyzed by Raman spectroscopy and XRD.

Degradation of polyethylene over solid acids and bases

Solid acids (ZSM-5, silica-alimina) and bases (MgO, ZnO) were employed as catalysts for the degradation of polyethylene powder at 673 K. The degradation rate over solid acids were more than two times higher than those over solid bases. The degradation products were gases (C1 to C4), oils (C5 to C20) and wax (higher than C21), analyzed by GC-MS to obtain a product distribution curve as a function of C-atom numbers. A relationship between the acid strength and amount and the product compositions were studied using silica-alumina catalysts with various Si/Al ratios, resulting in an enhancement in the gas production as the acid strength and amount increased.