Development of SI-traceable C-peptide certified reference material NMIJ CRM 6901-a using isotope-dilution mass spectrometry-based amino acid analyses

A certified reference material (CRM) is a higher-order calibration material used to enable a traceable analysis. This paper describes the development of a C-peptide CRM (NMIJ CRM 6901-a) by the National Metrology Institute of Japan using two independent methods for amino acid analysis based on isotope-dilution mass spectrometry. C-peptide is a 31-mer peptide that is utilized for the evaluation of β-cell function in the pancreas in clinical testing. This CRM is a lyophilized synthetic peptide having the human C-peptide sequence, and contains deamidated and pyroglutamylated forms of C-peptide. By adding water (1.00 ± 0.01) g into the vial containing the CRM, the C-peptide solution in 10 mM phosphate buffer saline (pH 6.6) is reconstituted. We assigned two certified values that represent the concentrations of total C-peptide (mixture of C-peptide, deamidated C-peptide, and pyroglutamylated C-peptide) and C-peptide. The certified concentration of total C-peptide was determined by two amino acid analyses using pre-column derivatization liquid chromatography-mass spectrometry and hydrophilic chromatography-mass spectrometry following acid hydrolysis. The certified concentration of C-peptide was determined by multiplying the concentration of total C-peptide by the ratio of the relative area of C-peptide to that of the total C-peptide measured by liquid chromatography. The certified value of C-peptide (80.7 ± 5.0) mg/L represents the concentration of the specific entity of C-peptide; on the other hand, the certified value of total C-peptide, (81.7 ± 5.1) mg/L can be used for analyses that does not differentiate deamidated and pyroglutamylated C-peptide from C-peptide itself, such as amino acid analyses and immunochemical assays.     

Formulation study on retinoic acid gel composed of iota-carrageenan, polyethylene oxide and Emulgen® 408

In the present study, all-trans retinoic acid (RA) gels formulated with various compositions of polyethylene oxide (Emulgen?) and iota-carrageenan (ι-CG) were prepared and their physicochemical properties were evaluated. The compression energy, which is the work required to compress the product through a fixed distance, increased with increasing amount of ι-CG or Emulgen?. The adhesion energy and displacement decreased with increasing amount of ι-CG or Emulgen? due to the progression of gel formation. From the results of the sensory tests, the properties of RA gels such as adhesiveness, gel strength and spreadability seemed to be adjustable depending on the condition of skin by varying the components of RA gels. Through photostability study, the expiration date and storage conditions of RA gels were determined as "4°C for 28?d with no exposure to light."     

Preparation of novel hydrophobic fluorine-substituted-alkyl sulfate ionic liquids and application as an efficient reaction medium for lipase-catalyzed reaction

Various types of differently fluorinated-alkyl sulfate ionic liquids have been prepared; the hydrophobicity was dependent on the content ratio of the fluorine on the alkyl sulfate anion and 2,2,3,3,4,4,5,5-octafluoropentyl sulfate salts showed hydrophobic properties. Melting point and viscosity were also dependent on the fluorine contents of the anionic part, while conductivity was determined by the cationic part and not influenced by the fluorine contents. Efficient lipase-catalyzed transesterification was demonstrated using hydrophobic 1-butyl-3-methylimidazolim 2,2,3,3,4,4,5,5-octafluoropentyl sulfate ([bmim][C5F8]) as solvent.     

Lipase-catalyzed kinetic resolution of 3-butyn-2-ol

Optically active 3-butyn-2-ol, an important building block, was synthesized successfully using lipase-catalyzed kinetic resolution. Starting from the thus obtained 3-butyn-2-ol, several 4-aryl-substituted compounds were synthesized enantioselectively.     

Daphmanidins C and D, novel pentacyclic alkaloids from Daphniphyllum teijsmanii

[structure: see text] Two novel alkaloids with an unprecedented fused-pentacyclic skeleton, daphmanidins C (1) and D (2), have been isolated from the leaves of Daphniphyllum teijsmanii, and the structures were elucidated on the basis of spectroscopic data. The relative stereochemistry of 1 and 2 was assigned by combination of NOESY correlations and a simulation analysis. Daphmanidin C (1) elevated activity of NGF biosynthesis.     

Determination of ethanol in alcoholic beverages by high-performance liquid chromatography-flame ionization detection using pure water as mobile phase

A method for the determination of ethanol in alcoholic beverages by high-performance liquid chromatography-flame ionization detection (HPLC-FID) was developed. An FID system could be directly connected to an HPLC system using pure water as a mobile phase. In a durability test using triacontylsilyl (C30)-silica gel stationary phase for 96 h, no significant change in the retention time of four alcohol compounds was observed. So the HPLC separation of alcoholic beverages was carried out on the C30-silica gel stationary phase. On application to the analysis of six kinds of alcoholic beverages, ethanol could be determined accurately by the proposed method.     

Synthesis and absolute configuration of methyl α-tetronitroside (kijanoside)

Synthesis of methyl α-D-tetronitroside($\text{11}$) from D-mannose via methyl α-D-mycaroside($\text{1}$) established the D-configuration for tetronitrose(kijanose), a novel nitro sugar which occurs as a component of the antitumor antibiotics tetrocarcins A and B, and kijanimicin.     

Stark beats of Lyman-α emission of foil-excited hydrogen atom

The Stark beats of Lyman-α emission due ton=1 ? 2 transition of hydrogen atom have been studied by the beam-foil method. After passage through a thin carbon foil, the static electric field of 500 V/cm was applied to the beam in the direction either parallel to or anti-parallel to the the beam velocity. The linearly polarized emission was measured by using a toroidal mirror at a Brewster's angle reflection. When the direction of the applied electric field is reversed, an appreciable phase shift was observed. The analysis of the data leads to the complete determination of the density matrix of the H(n=2) atoms at the time of their production.