Structural and conformational studies on citreoviridinol and isocitreoviridinol: syntheses of some 2,6-dioxabicyclo[3.2.1]octanes

Isocitreoviridinol has been newly isolated from the mycelium of $\text{Penicillium citreo-viride}$ B. (IFO 6050) together with citreoviridinol, and their stereostructures have also been elucidated by means of chemical method: the 2,6-dioxabicyclo[3.2.1]octanes have been made, one of which is regarded as a promising synthetic intermediate of citreoviridinol. In addition, isocitreoviridinol diacetate has been derived from citreoviridin in 3 steps.     

Rapid and highly sensitive method for determination of methamphetamine and amphetamine in urine by electron-capture gas chromatography

A rapid and sensitive method for determination of methamphetamine and amphetamine in urine was developed by using electron-capture gas chromatography. The extraction procedure, the experimental conditions for pentafluorobenzoyl derivative formation and the percentage recovery of the drugs from urine are described. The pentafluorobenzoyl derivative of methamphetamine showed a higher electron-capture sensitivity and was detected in at least 23-fold lower concentration than the heptafluorobutyryl derivative which is commonly used as a derivatizing agent for the amine. The detection limit of pentafluorobenzoyl derivatives of methamphetamine and amphetamine was ca. 10 pg. A concentration as low as 10 ng/ml of methamphetamine and amphetamine in urine was easily detected by this method.     

Preconcentration of copper,lead, cadmium and zinc ions from water with 2-mercaptobenzothiazole loaded on glass beads with the aid of collodion

2-Mercaptobenzothiazole (MBT) loaded on glass beads with the aid of collodion was prepared and used for selective preconcentration of μg l^?1 levels of copper(II) and lead from aqueous solutions. Copper and lead were quantitatively retained on the loaded beads from solutions of pH 5.0–6.0 and >5.0, respectively, while cadmium(II) and zinc(II) were retained at ? pH 6.0 and 7.0, respectively. The retention capacity of the loaded beads was ca. 108 μg Cu g^?1 (1.7 μmol g^?1) at pH 5.5 for beads of 0.3–0.4 mm diameter. The mole ratios of MBT to copper(II) and lead(II) were ca. 10 and 45, respectively, regardless of the amount of MBT loaded on the beads. Copper was completely retained on the column at a high flow rate (21.7 ml min^? cm^?2) and lead(II) at up to 12.7 ml min^? cm^?2. Cadmium(II) and zinc(II) were not retained quantitatively even at low flow rates (< 1.2 ml min^?1 cm^?2). Thus, selective preconcentration of copper and lead was achieved by passing the sample through the column at high flow rate at pH 6.5. The copper and lead retained on the column were complete eluted together with the collodion with 5 ml of MIBK by batch-mode elution, and determined directly by one-drop atomic absorption spectrometry. Copper(II) and lead(II) in several kinds of water were determined.     

Core-exciton induced resonant photoemission in the covalent semiconductor black phosphorus

Valence band photoemission spectra of black phosphorus have shown anomalous behavior at the excitation of 2p core-excitons. The intensity of the 2.7 ev peak shows a clear Fano type interference due to a direct recombination of core-excitons leaving one hole in valence bands. Besides, strong enhancement of the 10.8 eV peak is interpreted as due to a core-exciton induced resonance with two-hole final states. The role of core-excitons as intermediate states for photoemission processes is newly revealed in the experiments.     

The resolution of α-amino acid by chiral polymer-copper complex

The (N-benzyl-l-leucinato) copper(II) complex was shown pH titration to coordinate l-amino acids more strongly than d enantiomers. A chiral polymer complex, containing N-alkylated amino acid residue and copper(II) ion, was used partially to resolve some optically active amino acids. Unlike the (N-benzyl-l-amino acidate)-copper(II) complex, the polymer—copper(II) complex coordinates d-amino acids more strongly than l-enantiomers; the effect was explained by formation of (N,N-dialkylated-amino acidate) copper(II) complex in the polymer.     

Determination of germanium by hydride generation with reducing tube followed by graphite furnace atomic absorption spectrometry using CH4/Ar as sweeper gas

Summary A sensitive method for the hydride generation and graphite tube furnace atomic absorption spectrometric measurements with a reducing tube using mixed gas (CH₄ 10% + Ar 90%) as sweeper gas has been developed for the determination of germanium. Germanium hydrides were generated in a horizontal glass tube, in which a pellet of NaBH₄ was placed. 0.61/min of sweeper gas flow rate, 2,700° C of atomization temperature and 2.5–3 M of acidity range were the best experimental conditions. The strong supression of the germanium signal by Ni and Co was effectively eliminated with 1,10-phenanthroline and thiosemicarbazide was comparatively effective for Au. The reducing tube used in this technique is extremely simple and can be connected to all the types of graphite furnaces. A detection limit of 2 ng was obtained with a precision of 3–4%

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Germaniumbestimmung durch Hydriderzeugung im Reduktionsrohr und nachfolgende Graphitofen-AAS mit CH₄/Ar als Spülgas

Zusammenfassung Bei dem beschriebenen Verfahren werden die Hydride in einem horizontalen Glasrohr erzeugt, das eine NaBH₄-Perle enthält. Als optimale experimentelle Bedingungen ergaben sich: Spülgas (0,61/min) aus 10% CH₄ und 90% Ar, Atomisierungstemperatur 2700° C, 2,5–3 M Säure. Die starke Beeinflussung des Ge-Signals durch Ni und Co wurde mit Hilfe von 1,10-Phenanthrolin eliminiert, die Störung durch Au mit Hilfe von Thiosemicarbazid. Das verwendete Reduktionsrohr ist sehr einfach und kann für alle Arten von Graphitöfen benutzt werden. Die Nachweisgrenze beträgt 2 ng, die Reproduzierbarkeit 3–4%.

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Paper read at the Meeting of the Japan Society for Analytical Chemistry, June 1982