Endogenous synthesis of N-methylsalsolinol, an analogue of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, in rat brain during in vivo microdialysis with salsolinol, as demonstrated by gas chromatography-mass spectrometry.

N-Methylsalsolinol, an analogue of 1,2,3,6-tetrahydropyridine, is present in the brains of patients with Parkinson's disease. To determine the metabolic pathway for the synthesis of N-Methylsalsolinol in the brain, salsolinol was perfused through the striatum or the substantia nigra of the rat brain by in vivo microdialysis. N-Methylsalsolinol was detected in the brain dialysate samples during microdialysis with salsolinol using gas chromatography-mass spectrometry with selected-ion monitoring. These results demonstrate that endogenous N-methylation of salsolinol into N-methylsalsolinol occurs in the brain in vivo.     

121Sb Mössbauer spectroscopic study of a series of organoantimony(III) compounds

A systematic study of organoantimony(III) compounds, SbR₃, was attempted in view of the effect on Mössbauer parameters of the substituent on the aromatic ring. The Mössbauer parameters obtained in frozen organic solutions reflected the electronic effect caused by the characteristics of the substituents, electron donative or attractive, at the para position on the aromatic ring.     

Automatic extraction using the mini-column liquid chromatography method for analysis of drugs of abuse in biological fluids

Summary The preparation of an automatic extractor using ODS-minicolumn (25mm × 9mm i.d.) for analysis of drugs of abuse in biological fluids and its application are described. The auto-extraction method consists of the sequential operations, adsorption-washing (clean up)-elution(collection of the analyte) and regeneration of column, which continue repeatedly. Recoveries of drugs from spiked plasma and urine samples with the auto-extractor were almost quantitative at the optimum pH and much better than that of the conventional extraction with ether. Reproducibility of the auto-extraction was fairly good and the relative standard deviations of 10 measurements for methamphetamine, THC, morphine, cocaine and methaqualone in urine and plasma were from 0.55% to 4.35%. The simultaneous extractions of methamphetamine, THC, tranquilizers and their metabolites in urine with the autoextractor are presented as applications. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

Equivalent electric circuit analyses of ionic thermocurrent in sodium-doped CaF2 crystals

The characteristics of high-temperature ionic thermocurrent (HT ITC) in CaF₂ doped with different sodium concentrations were studied by the Teflon-insulated electrode ITC method. It was shown that, with increasing sodium concentration, the HT ITC band moved toward a Na⁺-F_V dipole band with a peak at 162 K. The results of analyses of the HT ITC spectra using an equivalent electric circuit proved that the activation energy of space charge migration related to HT ITC was also strongly dependent on the doped sodium concentrations if varied from 0.94 to 0.46 eV with increasing sodium concentration in our ITC study. In addition, the broadening of the Na⁺-F_V dipole band was observed in 3 nominal mole% NaF-doped CaF₂, which was accompanied by a considerable decrease of the activation energy from 0.46 to 0.29 eV without showing marked temperature shifts of the peak ITC bands.     

Protic NNN and NCN Pincer‐Type Ruthenium Complexes Featuring (Trifluoromethyl)pyrazole Arms: Synthesis and Application to Catalytic Hydrogen Evolution from Formic Acid

NNN and NCN pincer‐type ruthenium(II) complexes featuring two protic pyrazol‐3‐yl arms with a trifluoromethyl (CF₃) group at the 5‐position were synthesized and structurally characterized to evaluate the impact of the substitution on the properties and catalysis. The increased Brønsted acidity by the highly electron‐withdrawing CF₃ pendants was demonstrated by protonation–deprotonation experiments. By contrast, the IR spectra of the carbonyl derivatives as well as the cyclic voltammogram indicated that the electron density of the ruthenium atom is negligibly influenced by the CF₃ group. Catalysis of these complexes in the decomposition of formic acid to dihydrogen and carbon dioxide was also examined. The NNN pincer‐type complex 1 a with the CF₃ group exhibited a higher catalytic activity than the tBu‐substituted analogue 1 b . In addition, the bis(CF₃‐pyrazolato) ammine derivative 4 catalyzed the reaction even in the absence of base additives.     

Matrix effects on epithermal neutron activation analysis of various kinds of reference materials

The improvement obtained by epithermal neutron activation analysis was studied in terms of the detection sensitivity and precision in the γ-ray spectrometry for geological and biological reference samples. For geological samples, small improvement was observed only for the elements As, Ba, Sb, Se and U. For biological samples, however, large improvement was observed for As, Br, Sb and U. The ratio of the resonance integral to the effective thermal-neutron capture cross section was observed for 19 nuclides. The effect of the (n, p) reaction to the determination of Al and Mg by the ordinary reaktor-neutron activation analysis was estimated.     

Effect of pressure on the conductivities of HCl and KCl in water at 0°C

The electrical conductivities of hydrochloric acid and potassium chloride in water have been measured in the concentration range of 3×10 ^–4 –10 ^–3 moles-dm ^–3 at 0°C up to 3500 bar. The limiting molar conductance (₀) for HCl increases with increasing pressure, while ₀(KCl) has a maximum around 1700 bar. The excess conductance of hydrogen ion [ ₀ ^E =₀(HCl)–₀(KCl)] increases with increasing pressure. Its pressure dependence indicates that the reorientation of water molecules, which is the rate-determining step in the proton jump, becomes faster at higher pressure. This anomaly is attributed to the distortion with pressure of the hydrogen bonds in water.     

Liquid chromatography/mass spectrometric determination of patulin in apple juice using atmospheric pressure photoionization

This paper describes a comparison between atmospheric pressure chemical ionization (APCI) and the recently introduced atmospheric pressure photoionization (APPI) technique for the liquid chromatography/mass spectrometric (LC/MS) determination of patulin in clear apple juice. A column switching technique for on-line extraction of clear apple juice was developed. The parameters investigated for the optimization of APPI were the ion source parameters fragmentor voltage, capillary voltage, and vaporizer temperature, and also mobile phase composition and flow rate. Furthermore, chemical noise and signal suppression of analyte signals due to sample matrix interference were investigated for both APCI and APPI. The results indicated that APPI provides lower chemical noise and signal suppression in comparison with APCI. The linear range for patulin in apple juice (correlation coefficient >0.999) was 0.2-100 ng mL(-1). Mean recoveries of patulin in three apple juices ranged from 94.5 to 103.2%, and the limit of detection (S/N = 3), repeatability and reproducibility were 1.03-1.50 ng mL(-1), 3.9-5.1% and 7.3-8.2%, respectively. The total analysis time was 10.0 min.     

Studies directed toward the synthesis of protein-bound GPI anchor

Mannobioside-linked phosphoethanolamine 10, a prototype model of the GPI anchor, was synthesized via glycosidation of the monosaccharide donor and acceptor, and subsequent phosphorylation. In order to test the reactivity of the amino group involved in 10 against the activated amino acid esters, 10 was reacted with N-protected amino acid pentafluorophenyl esters in the presence of HOBt. The reactions gave the aminoacylated products in moderate yields. When Fmoc-Ser-OPfp 12 and Fmoc-Cys(SBu^t)-OPfp 14 were reacted with 10, byproducts 19, 20 and 21 derived from N- and O-acylation were produced. In contrast, reactions of 10 and N-protected amino acid thioesters were promoted with AgNO₃, HOSu, and DIEA to afford the coupling products without the undesired O-acylation. Peptidylation of 10 with the synthesized oligopeptide thioesters 24 and 27 was also successful under the segment coupling conditions of the peptide thioester method as well as those of the native chemical ligation.     

Chemical synthesis of 23 kDa glycoprotein by repetitive segment condensation: a synthesis of MUC2 basal motif carrying multiple O-GalNAc moieties

Peptide thioester corresponding to a MUC2 tandem repeat unit, which retains seven GalNAc moieties, was prepared by the Fmoc method followed by the low TfOH treatment to remove benzyl groups at the carbohydrate portions. The glycosylated peptide thioester was then consecutively joined by the activation of a thioester group by silver ions to obtain a MUC2 tandem repeat model composed of 141 amino acids with 42 GalNAc moieties.