Development of a novel potentiometric titration method for determination of polypropylene degradation

In this study, a novel potentiometric titration of hydroperoxide in degraded polypropylene (PP) is proposed. This titration is quite sensitive compared with the conventional ones such as UV and manual titrations, and its detection limit was about 2 meq/kg. The sensitivity was equal to that of molecular weight measurement by GPC for the degraded PP and, in addition, the volatilization behavior of the hydroperoxide could be detected. This titration was found to be very effective for the determination of PP degradation.     

Preparation of rapidly disintegrating tablet using new types of microcrystalline cellulose (PH-M series) and low substituted-hydroxypropylcellulose or spherical sugar granules by direct compression method

To decrease the sensation of roughness when a tablet, which is rapidly disintegrated by saliva (rapidly disintegrating tablet), is orally taken, we prepared rapidly disintegrating tablets using microcrystalline cellulose (Avicel PH-M series), a new type of pharmaceutical excipient that is spherical and has a very small particle size (particle size, 7-32 microm), instead of conventional microcrystalline cellulose (PH-102) used in the formulation of tablets containing acetaminophen or ascorbic acid as model drugs for tableting study. Tablets (200 mg) prepared using spherical microcrystalline cellulose, PH-M-06, with the smallest particle size (mean value, 7 microm) had sufficient crushing tolerance (approximately, 8 kg) and were very rapidly, disintegrated (within 15 s) when the mixing ratio of PH-M-06 to low-substituted hydroxypropylcellulose (L-HPC) was 9:1. Sensory evaluation by volunteers showed that PH-M-06 was superior to PH-102 in terms of the feeling of roughness in the mouth. Consequently, it was found that particle size is an important factor for tablet preparation using microcrystalline cellulose. It is possible to prepare drugs such as acetaminophen and ascorbic acid (concentration of approximately 50%) in the tablet form using PH-NM-06 in combination with L-HPC as a good disintegrant at a low compression force (1-6 kN). To solve the problem of poor fluidity in the preparation of these tablets, we investigated the use of spherical sugar granules (Nonpareil, NP-101 (sucrose and starch, composition ratio of 7:3), NP-103 (purified sucrose), NP-107 (purified lactose) and NP-108 (purified D-mannitol)). Rapidly disintegrating tablets can be prepared by the direct compression method when suitable excipients such as fine microcrystalline cellulose (PH-M-06) and spherical sugar granules (NP) are used.     

Profiling analysis of oligosaccharides in antibody pharmaceuticals by capillary electrophoresis

Carbohydrate chains in glycoprotein pharmaceuticals have important roles for the expression of their biological activities. Therefore, development of an assessment method for the carbohydrate chains is an important parameter for quality control of glycoprotein pharmaceuticals such as newly developed therapeutic antibodies. In this report, we applied capillary electrophoresis with laser-induced fluorescence detection to the analysis of carbohydrate chains after releasing with glycoamidase followed by derivatization with 3-aminobenzoic acid. We found that four major oligosaccharides present in antibody pharmaceuticals were successfully separated with good resolution. The present method showed good precision in both migration times and relative peak areas, and gave comparable accuracy with that using a derivatization method with 8-aminopyrene-1,3,6-trisulfonate.     

Lewis acid-catalyzed asymmetric hydroxymethylation of silicon enolates in aqueous media

Asymmetric hydroxymethylation of silicon enolates with formaldehyde in aqueous media has been achieved using praseodymium triflate and a chiral crown ether. Formaldehyde aqueous solution can be directly used for the reactions, and a water/THF mixture was found to be the best solvent system. This is the first example of catalytic asymmetric hydroxymethylation of silicon enolates.     

Application of proton induced X-ray emission to the qualitative and quantitative analysis of iodine in biological samples

Particle-induced X-ray emission (PIXE) was applied to evaluate the loss of volatile elements such as iodine in biological samples. The analytical quality of the method is comparable or better than spectrophotometry, which is currently believed to be the most reliable for iodine determination. The temperature dependence of volatility loss of trace iodine was characteristic, and the feature was divided into three temperature regions. The first one, ranging from room temperature to 200 °C, showed only a slight loss below 20% on drying; the second stage, between 200 °C and 350 °C, where carbonizing processes became prominent, showed a remarkable loss up to 50%; the last one, beyond 350 °C, was accompanied by a considerable loss of iodine (more than 80%) with ashing. Even in the analysis using low temperature ashing with oxygen plasma, the loss of iodine observed was considerable (nearly 80%). The significance of these findings by PIXE in trace analysis is noted to improve analytical quality of volatile elements, such as iodine in biological, medical and also environmental fields.     

Photo-induced dimerization of 1-naphthoxide anion: Electron transfer mechanism

Irradiation of sodium 1-naphthoxide in MeOH gave selectively 1,4-dihydro-4',8-dihydroxy-1,1'-binaphthyl 2. A similar reaction in PhH afforded the regioisomer 5, along with 6, Structural proof is presented for these hitherto unknown dimers. The reaction is completely quenched in the presence of naphthalene, a good electron scavenger. This new type of photodimerization was proved to be initiated by intermolecular electron-transfer from the excited 1-naphthoxide anion to the ground state one to give the oxidation-reduction dimers.     

Mechanism of external heavy-atom enhancement of the radiative transition rate from the π,π* triplet state

The effect of external heavy-atom perturbation is examined for each of the three spin subcomponents of the π,π^* triplet state. It is shown that the radiative decay rate from the subcomponent whose spin wavefunction is within the molecular plane is most effectively enhanced. The main perturbing singlet state is the charge-transfer state arising from the excitation of an electron from a π orbital of the molecule to the σ^* orbital of the perturber.     

Preparation and characterization of carbonated barium-calcium hydroxyapatite solid solutions

Particles of carbonated barium-calcium hydroxyapatite solid solutions (BaCaHap) with different Ba/(Ba+Ca) (X(Ba)) atomic ratios were prepared by a wet method at 100 degrees C and characterized by various means. The crystal phases and structures of the products strongly depended on the composition of the starting solution, that is, the Ba/(Ba+Ca) atomic ratio ([X(Ba)]) and H3PO4 concentration ([H3PO4]) in the solution. BaCaHap with X(Ba)0.43 could be prepared at [X(Ba)]0.7 by changing [H3PO4], but could never be obtained at [X(Ba)]=0.8-0.95 regardless of [H3PO4]. The carbonated calcium hydroxyapatite particles prepared at [X(Ba)]=0 were fine and short rod-shaped particles (ca. 14x84 nm). With increasing [X(Ba)] from 0 to 0.8, the particles obtained became large spherical agglomerates. The carbonated barium hydroxyapatite particles formed at [X(Ba)]=1 were long rod-shaped agglomerates (ca. 0.2x2 microm) of fine primary particles. The amount of CO2 adsorbed irreversibly on a series of BaCaHaps showed a minimum at (Ba+Ca)/(P+C) atomic ratio of around 1.56, which agreed well with the minimum cation/P ratio obtained for the other hydroxyapatites, as already reported.