12 research outputs found
Characterization, quantification and minimization of protein aggregates in solution for improvement of protein pharmaceuticals
Preparation of Polybutylene Oxides Bearing Terminal Ester Groups by Treatment of H[(CH_2)_4O]_nSiR_3 with Acyl Halides
Utilization of a precolumn with size exclusion and reversed-phase modes for size-exclusion chromatographic analysis of polysorbate-containing protein aggregates.
Size-exclusion chromatography (SEC) is a useful method for quantification of protein aggregates because of its high throughput capacity and highly quantitative performance. One of the problems in this method concerns polysorbates, which are well-known additives for protein-containing products to prevent protein aggregation, but frequently interfere with the photometric detection of protein aggregates. We developed a new SEC method that can separate polysorbates from protein sample solutions in an on-line mode with a precolumn with size exclusion and reversed-phase mixed modes. The precolumn can effectively trap polysorbates in aqueous mobile phase, and the trapped polysorbates are easily eluted with acetonitrile-containing aqueous mobile phase to clean the precolumn. Small parts of protein aggregates may be also trapped on the precolumn depending on temperature and proteins. Setting appropriate column temperature can minimize such inconvenient trapping of aggregates
Practical Procedures for Hydrosilylation of Ketones and Silane-induced Ring-opening Polymerization of Cyclic Ethers by Prior Activation of the Cluster Catalyst by Hydrosilanes : Improved Synthetic Procedures and Mechanistic Implication on the Catalytically Active Species
Preparation of Polybutylene Oxides Bearing Terminal Ester Groups by Treatment of H[(CH_2)_4O]_nSiR_3 with Acyl Halides
Treatment of H[(CH_2)_4O]_nSiR_3, which were prepared by the silane induced polymerization of THF with acyl halides catalyzed by (μ_3:η^2:η^3:η^5-acenaphthylene)Ru_3(CO)_7, provides a novel synthetic method for polybutylene oxides bearing terminal ester groups. Various acyl halides such as acetyl chloride, benzoyl bromide, adipoyl chloride, acryloyl chloride, and 2-bromoisobutyryl bromide could be used as the acyl halide component; the reactivity of acyl halides increased in the order RCOBr>RCOCl>RCOF, whereas little difference in reactivity was observed among poly-butylene oxides bearing PhMe_2Si-, Et_3Si-, and EtMe_2Si- moieties. All of the products were completely characterized by IR, ^1H, ^<13>C, H-H, and H-C COSY NMR techniques, revealing that they have one terminal butyl and one terminal acyloxy groups. In the case of the reaction with adipoyl chloride, a polymer having two H[(CH_2)_4O]_n units at both ends of the adipoyl moiety was available. The methodology involving the silane-induced ring-opening polymerization followed by treatment with acyl halides was also applied to the synthesis of polycyclohexene oxide bearing 2-bromoisobutyryl bromide. The polymers bearing isobutyryloxy or acryloyloxy groups could be used as a macroinitiator or macromonomers to produce other functional polymers
Practical Procedures for Hydrosilylation of Ketones and Silane-induced Ring-opening Polymerization of Cyclic Ethers by Prior Activation of the Cluster Catalyst by Hydrosilanes : Improved Synthetic Procedures and Mechanistic Implication on the Catalytically Active Species
Pre-activation of (μ_2,η^2:η^3:η^5-acenaphthylene)Ru_3(CO)_7 (1) by hydrosilanes in a small amount of dioxane provides novel convenient and useful procedures for hydrosilylation of carbonyl compounds and silane-induced ring-opening polymerization of cyclic ethers and a cyclic siloxane. The initial step of the catalytic cycle was investigated by NMR detection of products formed by the oxidative addition ofhydrosilanes to 1. A possibility for the involvement of cluster species in the catalytic cycle is discussed
Utilization of a precolumn with size exclusion and reversed-phase modes for size-exclusion chromatographic analysis of polysorbate-containing protein aggregates
Sensitive and Comprehensive Detection of Chemical Warfare Agents in Air by Atmospheric Pressure Chemical Ionization Ion Trap Tandem Mass Spectrometry with Counterflow Introduction
A highly
sensitive and specific real-time field-deployable detection
technology, based on counterflow air introduction atmospheric pressure
chemical ionization, has been developed for a wide range of chemical
warfare agents (CWAs) comprising gaseous (two blood agents, three
choking agents), volatile (six nerve gases and one precursor agent,
five blister agents), and nonvolatile (three lachrymators, three vomiting
agents) agents in air. The approach can afford effective chemical
ionization, in both positive and negative ion modes, for ion trap
multiple-stage mass spectrometry (MS<sup><i>n</i></sup>).
The volatile and nonvolatile CWAs tested provided characteristic ions,
which were fragmented into MS<sup>3</sup> product ions in positive
and negative ion modes. Portions of the fragment ions were assigned
by laboratory hybrid mass spectrometry (MS) composed of linear ion
trap and high-resolution mass spectrometers. Gaseous agents were detected
by MS or MS<sup>2</sup> in negative ion mode. The limits of detection
for a 1 s measurement were typically at or below the microgram per
cubic meter level except for chloropicrin (submilligram per cubic
meter). Matrix effects by gasoline vapor resulted in minimal false-positive
signals for all the CWAs and some signal suppression in the case of
mustard gas. The moisture level did influence the measurement of the
CWAs
Assessment Report of Doctoral Theses
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