A SENSITIVE METHOD FOR DETERMINING CHLOROPHYLL b IN PLANT EXTRACTS

Abstract— A new method of using hydroxylamine as the reagent was developed to determine the concentrations of chlorophylls a and b in plant extracts accurately and sensitively. The method is based on the principle that hydroxylamine reacts in a short time with the aldehyde group of chlorophyll b in 95 per cent methanol at pH 5.8 to afford a derivative having a red band similar in position to the red band of chlorophyll a , while the spectrum of chlorophyll a is unaffected by the treatment with hydroxylamine. The method includes the measurements of absorbanlce for the mixture of a plant extract with hydroxylamine and for the reagent blank at a single wavelength, 666 mμ, and the concentrations of chlorophylls a and b are calculated from the absorbance value for the reagent blank and the increment of absorbance due to the reaction. By measuring this increment directly by difference photometry, one can determine a low concentration of chlorophyll b relative to chlorophyll a . The contents of chlorophylls in matured and etiolated leaves were determined by the method, and the errors included in this method were shown to be smaller than those in a commonly used technique including the measurements at two different wavelengths.     

Synthesis of pyrimidinopurinophanes

Synthesis and structures of the title compounds 2a–d are described. In spite of non-parallel orientation of the two base rings, fairly large hypochromism was observed for 2a–d.     

On the correlation between NQR frequency and bond length in I3−

A linear correlation between the NQR frequency of the terminal iodine atom and the corresponding I-I bond length in I₃^? was found in several compounds containing triiodide anions. A simple extended Huckel MO calculation suggested that such a correlation can be used to check the validity of wavefunctions of iodine.     

Radiocarbon dating of an ancient Japanese document “Minamoto no Yoritomo Sodehan Migyosho” by accelerator mass spectrometry

We measured radiocarbon age of an ancient document “Minamoto no Yoritomo Sodehan Migyosho”. The content tells that it was issued in 1189 by “Minamoto no Yoritomo” known as the virtually first shogun in Japan to grant “Matsugi” family the privilege of controlling craftsmen of foundry industry. Paleographical views, however, suggested that it can be a counterfeit. The radiocarbon dating clarified that the document was written not in the 12th but after the 16th century.     

Hydrothermal synthesis of potassium molybdenum oxide bronzes: structure-inheriting solid-state route to blue bronze and dissolution/deposition route to red bronze

The hydrothermal syntheses of the alkali metal molybdenum bronzes from starting solids (H_xMoO₃) with structural affinities to the desired products were investigated. Single-phase potassium blue and red bronzes were prepared by the hydrothermal treatments at around 430 K, and characterized by powder X-ray diffraction, IR spectroscopy, and SEM. The formation processes of these two bronzes during the hydrothermal treatments were found to differ. The blue bronze was formed by a structure-inheriting solid-state route from H_xMoO₃ with x<0.3, whereas the red bronze was formed for x>0.3 through a solution dissolution/deposition route via the formation of MoO₃+MoO₂.     

Synthesis and metal-ion binding properties of monoazathiacrown ethers

Synthetic procedures for monoazathiacrown ethers were explored, and monoazatrithia-12-crown-4, monoazatetrathia-15-crown-5, and monoazapentathia-18-crown-6 were obtained in moderate yields by the reaction of bis(2-chloroethyl)amine with the appropriate dithiols in the presence of lithium hydroxide in THF. To evaluate metal-ion binding properties of the monoazathiacrown ethers by solvent extraction, lipophilic dodecyl and dodecanoyl groups were incorporated onto the monoazathiacrown ethers. The solvent extraction experiments suggested that monoazathiacrown ethers have Ag(+) and Hg(2+) selectivities and that the relative selectivity between Ag(+) and Hg(2+) depends on their nitrogen atom properties and numbers of sulfur atoms reflecting the respective affinities of nitrogen and sulfur atoms to Hg(2+) and Ag(+). An interesting ability to bind Mg(2+) was observed in the case of N-dodecyl monoazatrithia-12-crown-4.