1. Caffeine reacts with haematin to form a caffeine-haematin compound that has a characteristic absorption spectrum. 2. Graphical analysis of the titration of haematin with caffeine shows that 2mol.prop. of caffeine split the dimeric haematin. 3. Thermodynamic parameters suggest that the reaction involves the making and breaking of hydrophobic bonds. 4. Graphical analysis shows dimeric haem to ...

The ultrasonic absorption of aqueous solutions of salmon sperm deoxyribose nucleic acid (DNA), molecular weight of the order of 106, was determined as a function of pH in the neutral and acidic regions over the frequency range 5-50 MHz at 25øC. Tile viscous relaxation frequencies appear to be well below 1 MHz. At neutral pH values, viscosity and molecular conformation appear to contribute littl...

The principle of flow ratiometry for high-throughput titration, which we recently proposed for potentiometric titration, was extended to photometric titration. The flow rate (FB) of a base solution containing an acid-base indicator was linearly varied in response to a control voltage (Vc) generated from a computer. With the total (acid + base) flow rate (FT) being kept constant, the base soluti...

Department of Chemistry, Faculty of Sc Yokohama, 223-8522, Japan. E-mail: hasob Department of Material and Life Science, University, ALCA, Japan Science and Tech 0871, Japan. E-mail: [email protected] Department of Applied Physics, Waseda U 169-8555, Japan. E-mail: takenobu@waseda † Electronic supplementary information MALDI-TOF mass spectra, cyclic vo uorescence titration spectra, H NMR tra...

The gravimetric analysis of antimony(III) with oxine (8-quinolinol, Hox) was studied. The amount of antimony left in filtrate and washing solutions was corrected with the results of atomic absorption spectrometry. The weighing form, which had not been conclusive before the present study, was determined to be SbO(ox)(Hox)2. The result (purity of antimony(II) oxide: 99.84 +/- 0.05% (m/m)) of the ...

1. A stable ternary complex of salicylate hydroxylase apoenzyme, flavin adenine dinucleotide, and salicylate was detected by a change of the absorption spectrum and by titration of the holoenzyme with salicylate. 2. The complex was enzymatically active, since the stoichiometric formation of the product, catechol, was observed upon introduction of air into a solution of reduced form of the compl...

A method for electronic doping of colloidal CdSe nanocrystals (NCs) is reported. Anaerobic photoexcitation of CdSe NCs in the presence of a borohydride hole quencher, Li[Et3BH], yields colloidal n-type CdSe NCs possessing extra conduction-band electrons compensated by cations deposited by the hydride hole quencher. The photodoped NCs possess excellent optical quality and display the key spectro...

The interaction of a new derivative of thiazole orange (TO-3) with calf thymus DNA (ctDNA) has been investigated by fluorescence and absorption spectroscopy. When TO-3 binds to ctDNA, absorption bands exhibit significant hypochromicity at low base pair/dye ratio (BP/D ratio), and high BP/D show hyperchromicity with red shift. The spectral changes are attributed to the different species formed b...

Accurate normalization of X-ray absorption data is essential for quantitative analysis of near-edge features. A method, implemented as the program MBACK, to normalize X-ray absorption data to tabulated mass absorption coefficients is described. Comparison of conventional normalization methods with MBACK demonstrates that the new normalization method is not sensitive to the shape of the backgrou...

A multiwavelength spectrophotometric (WApH) titration method for determination of acid dissociation constants (pK(a) values) of ionizable compounds developed previously was applied in the case of pyridine derivatives of pharmaceutical interest. Specifically, UV absorption spectra of the drug solution are acquired in the course of a pH-metric titration using an optical device based on a fibre op...