Kenyu Kina

Sensitivity Enhancement of the Fluorometric Determination of Aluminum by the Use of Surfactant

Abstract The effects of surfactants on fluorescence analysis were studied. The addition of surfactants to a metal complex solution causes a remarkable enhancement of fluorescence. By means of such phenomenon the sensitivity of the fluorometric determination of aluminum was increased about six-fold over conventional methods. From the stability of the chelate complex in the presence of surfactant and the degree of enhancement of fluorescence, the nonionic surfactant was judged to be the most useful of the types of surfactants: cationic, anionic and nonionic. An ultramicro amount of aluminum, 5 × 10−10 g Al/ml, could be determined by the proposed method.

Water-soluble pyridylazoaniline reagents for the spectrophotometric determination of metals : Determination of Iron(II) with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)aniline

Abstract Three water-soluble pyridylazoaniline reagents were synthesized and their application as spectrophotometric reagents for iron(II), copper(II), nickel(II) and cobalt(III) was investigated. Of the three reagents, 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)aniline (5-Br-PSAA) was found to be very sensitive (ϵ = 8.9 × 104 l mol−1 cm−1 at 558 nm, pH 4.3) and selective for iron(II). The iron(II) complex has a 1:2 metal/reagent ratio and, once formed, is not decomposed by EDTA, whereas the copper(II) and nickel(II) complexes are readily decomposed by EDTA. Thus, 5-Br-PSAA is useful for the determination of traces of iron(II) in biological samples, and is successfully applied to blood serum. The reagent is four times more sensitive than bathophenanthroline for iron(II). High sensitivity is also obtained for cobalt(III) in 3 M hydrochloric acid.

Highly sensitive enzymatic spectrophotometric determination of hydrogen peroxide with water-soluble diphenylmethane-based derivatives

Abstract Five water-soluble diphenylmethane derivatives were synthesized. They give colored products by condensation with 3-methylbenzothiazolinonhydrazone in the presence of hydrogen peroxide and peroxidase. These reactions are useful for the enzymatic determination of hydrogen peroxide. The absorption maxima and the molar absorptivities of the chromogens lie in the ranges 560–600 nm and 5–9 × 10 4 l mol −1 cm −1 , respectively. The optimum pH range for color formation is 6.5–7.5. Calibration graphs for the determination of hydrogen peroxide are linear for 3–20 × 10 −6 mol H 2 O 2 l −1 . Di[4-(3-sulfopropylethylamino)phenyl]methane, disodium salt, is the best of the reagents tested.

Selective determination of gallium by flow injection fluorimetry

Abstract Gallium can be determined fluorunetrically, with linear response in the range 2.2 × 10-5 M–1.08 × 10-4 M, by means of chelate formation with lumogallion ; fluorescence is enhanced by mixing with a polyethylene glycol monolauryl ether solution. Up to 10-fold molar amounts of aluminum can be tolerated, because of the slow formation rate of the aluminum—lumogallion chelate.

Effects of taurine on the ATPase activity in the human erythrocyte membrane.

Effects of taurine on the total ATPase activity inhibited by ouabain were investigated in the human erythrocyte membrane. The enzyme activity was not activated by taurine in the absence of calcium, but was significantly activated by taurine (15-60 mM) in the presence of calcium (5 mM) by which the enzyme is inhibited. Since taurine does not form a chelate complex with calcium ion, this activation may be due to an action of taurine in the presence of calcium through competition with these ions on the membrane.

New Detection Method of end Point in Colloid Titration Using an Iodide Ion-Selective Electrode

Abstract A new potentiometric method using iodide ion as an indicator is proposed for the detection of the end point in a titration of the negatively charged colloid. An iodide ion-selective electrode is used to follow the change of the iodide ion activity in the titration of polyvinyl sulfate (PVS) with tetradecyl dimethylbenzyl ammonium chloride (Zephiramine). A decrease of the activity of the indicator, starting immediately after an equivalence point is passed, is shown to be a good indication of the equivalence point of the titration.

Effects of organic pH buffers on a cell growth and an antibody production of human-human hybridoma HB4C5 cells in a serum-free culture

Human-human hybridoma cells secreting a human monoclonal antibody were cultured in a serum-free medium containing various organic pH buffers in order to clarify their effects on cell growth and antibody production. Organic pH buffers having either one sulfonic acid and several acyclic amine moieties, or several cyclic amine moieties containing two amino nitrogen did not inhibit cell growth; while other organic buffers sulfonic acid moiety plus several cyclic amine moieties containing one amino nitrogen slightly decreased cell growth, but enhanced antibody production. Using Fujitas organic conceptual diagram, a relationship between the organicity and inorganicity of a pH buffer to cell growth and antibody production was found. pH buffers with large inorganicity and small organicity values were favorable for cell growth, and buffers with small inorganicity and large organicity values were preferred to enhance antibody production. Although the pH buffering range affects cell growth, its effect on antibody production is not clear. In conclusion, 2-morpholinoethanesulfonic acid (MES), 3-morpholino-propanesulfonic acid (MOPS) and 1, 2-N, N′-bis[N″, N‴-di(2-sulfonoethyl)piperazinyl]ethane (Bis-PIPES) are shown to be the most optimal of the buffers tested, because they enhanced antibody production without decreasing the cell growth among the pH buffers tested here.

Synthesis of a new tetrazolium salt giving a water-soluble formazan and its application in the determination of lactate dehydrogenase activity

Abstract A pyridine analog of 3-(4-,5dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide was synthesized. The new reagent, 2-phenyl-3-(4,5-dimethyl-2-thiazolyl)-5-(4-pyridyl)tetrazolium bromide, gave a water-soluble formazan dye on enzymatic reduction and was applied in the spectrophotometric determination of lactate dehydrogenase (0–84 mU ml −1 ) in blood serum. The sensitivity (ϵ = 1.83 × 10 4 l mol cm −1 at 539 nm) was about 70% of that obtainable with nitrotetrazolium blue.