Masataka Moriyasu

Microdetermination of Heavy Metal Chelates by High-Performance Liquid Chromatography

Abstract Adsorption chromatography of diethyldithiocarbamate chelates of heavy metals is described. Determination of heavy metals including Hg (II), Cd (II), Pb (II), Cr (VI), Bi (III) and Cu (II) in micro to nano gram order is successfully carried out with good accuracy and reproducibility by a deactivated silica gel column. Separative microdetermination of these chelates is accomplished within 12 min, and selective determination is also possible by choosing the detection wavelength of a UV detector.

Quantitative analysis of phenethylamine derivatives by thin layer chromatography. Determination of psychotropic drugs and ephedra bases

SummaryThe reactions between phenethylamine derivatives and sodiumβ-naphthoquinone-4-sulfonate were investigated. In weakly alkaline condition, amphetamine, methamphetamine, 2,5-dimethoxy-4-methylamphetamine and mescaline, which are the most representative awaking drugs, gave strongly colored reaction products. Under optimum conditions, the recovery was found to be almost complete and ng order detection was easily carried out. The results of TLC of these colored products suggest that this method is useful for the detection of these drugs, especially for screening purpose. Quantitative analysis was also possible. This method was applied to the separate determination ofl-ephedrine andd-ø-ephedrine inEphedra herba.ZusammenfassungDie Reaktionen von Natrium-β-naphthochinon-4-sulfonat mit Phenäthylamin-Derivaten wurden untersucht. Bei schwach alkalischer Reaktion geben die bekanntesten Weckamine Amphetamin, Methamphetamin, 2,5-Dimethyl-4-methylamphetamin und Meskalin stark gefärbte Reaktionsprodukte. Unter optimalen Bedingungen ist die Ausbeute fast vollständig, der Nachweis von ng-Mengen ist leicht durchführbar. Die Ergebnisse der Dünnschichtchromatographie dieser gefärbten Produkte erweisen die Nützlichkeit des Verfahrens zum Nachweis dieser Drogen. Auch die quantitative Bestimmung war möglich. Das Verfahren wurde zur Bestimmung vonl-Ephedrin undd-ø-Ephedrin nebeneinander inEphedra herba angewendet.

Kinetic studies of fast equilibrium by means of high-performance liquid chromatography : XV. Separation of tautomers of β-diketoesters

Abstract Keto-enol tautomerism of sixteen β-diketoesters, including cyclic ones, has been investigate using low-temperature high-performance liquid chromatography (HPLC) for analytical measurements. Keto-enol tautomers of these β-diketoesters have been successfully separated on chemically bonded silica gel packings which contain hydroxyl-groups (diol-type column packings). These phases gave much better results than the usual silica gel packings. Base-line separation of keto- and enol-tautomers of the β-diketoesters has been achieved on diol-type column packings with a mobile phase consisting of hexane and a small amount of 1-propanol and at a higher column temperature than on silica gel packings. The interconversion between tautomers of 2-alkyl-substituted β-diketoesters is so slow that keto- and enol-tautoesters have been separated even at 25°c on diol-type column packings. The ratios of keto- and enol-tautomers have been determined by HPLC in different solvents, and showed good agreement with data previously reported. The presence of other species in equilibrium, such as hemiacetals and possibly unconjugated enol-tautomers has been observed for some of the β-diketoesters tested.

Studies on the reactions of PtCl2en, cis-Pt(NH3)2Cl2 and their aqua species with adenosine, deoxyadenosine and adenine using ion-pair HPLC

Abstract The reactions of PtCl 2 en or cis -Pt(NH 3 ) 2 Cl 2 and their aqua species with adenine and adenosine were studied by means of ion-pair HPLC. From the chromatograms, it was found that the first binding site of Pt(II) was the N(7) site of adenine under both acidic and neutral conditions. The rates of Pt(II) binding at the (N7) site of adenosine and deoxyadenosine were measured. The rate constants, k 1 , were obtained for the reactions of PtCl 2 en or cis -Pt(NH 3 ) 2 Cl 2 with adenosine and deoxyadenosine at pH 3 and 7 over the temperature range 9–25 °C. The k 1 values were 6.8–7.7 × 10 −4 dm 3 mol −1 s −1 at 25 °C. For the aqua species, the rate of [ cis -Pt(NH 3 ) 2 ClH 2 O] + with adenosine N(7) was measured. The rate constants, k 2 which were found to be smaller than those of hydrolysis, k h , were calculated at pH 3 over the temperature range 25–40 °C. The k 2 value obtained at 25 °C was 1.1 × 10 −2 dm 3 mol −1 s −1 , 15 time larger than k 1 . The activation parameters were also calculated.

A Semicontinuous Assay of Inhibition of Cyclic-AMP Phosphodiesterase by Benzo[c]phenanthridine Alkaloids

Abstract An HPLC apparatus to trace the reaction semicontinuously was devised and applied to the kinetic study of an enzyme reaction. From the thermostated solution in which the reaction proceeds continuously, an aliquot of the solution was removed and submitted to HPLC automatically and repeatedly. Thus, the change of concentrations of reactant and/or product was determined at a definite short interval. The inhibitory action of cyclic-/ P phosphodiesterase (PDE) by several benzo[c]phenenthridine alkaloids was examined. From 1/S–1/V (Lineweaver-Burk plot) sanguinarine and chelerythrine, which were both potent bacteriocidal alkaloids, were found to strongly inhibit PDE competitively. Kinetic parameters of the enzyme reaction such as Michaelis constant and inhibition constants were obtained.

Capacitance-conductance detector for high-pressure liquid chromatography. Application to alkaloids and fatty acids

SummaryA new type of detector for high-pressure liquid chromatography has been designed. This detector is equipped with a RC resonance circuit, and is similar to the capacitance detector previously reported. It is operated as a capacitance detector with nonpolar eluents; while with polar solvents, it behaves as a conductance detector. Electrolytes such as salts, acids and bases are sensitively detected. The detector was successfully used for the detection of fatty acids and alkaloids.ZusammenfassungEin neuartiger Detektor für die Hochdruck-Flüssigchromatographie wurde entwickelt. Dieser ist mit einem Resonanzstromkreis ausgestattet und ähnelt dem kürzlich beschriebenen Kapazitanz-Detektor. Als solcher funktioniert er mit nichtpolaren Eluenten, während er sich mit polaren Lösungsmitteln wie ein Leitfähigkeitsdetektor verhält. Salze, Säuren und Basen werden empfindlich nachgewiesen. Das Gerät wurde zum Nachweis von Fettsäuren und Alkaloiden verwendet.

Chapter 1 Forensic Chemistry of Alkaloids by Chromatographic Analysis

Publisher Summary There have been numerous psychoactive alkaloids found in the plant kingdom since morphine was first isolated by Setiirner in 1832. Opium, which contains morphine and related alkaloids, was well known as an analgesic to the ancients. Cocaine was found in coca leaves in 1860 and has been used in South America as a masticatory since early times. Cocaine and its salts are the oldest local anesthetics but their use is now entirely regulated because of their toxic and addictive properties. The chemical reactions of drugs and synthetic organic compounds in the body occur through oxidation, reduction, hydrolysis, or conjugation resulting in activation or inactivation. Chemistry has made it possible for psychoactive compounds from nature to be synthetically converted into more active and less toxic compounds, but some are now controlled by law. This chapter reviews chromatographic techniques for identification of legal and illegal forensic and psychoactive compounds available in illicit markets and in biological samples, as well in plants used by primitive and civilized peoples.

Microdetermination of Bile Acids by High-Performance Liquid Chromatography Equipped with a High Sensitive Conductance Detector

Abstract Conductimetric detection of bile acids in reversed phase high-performance liquid chromatography is described. The solvent system of the mixture of water and organic solvent containing small amount of basic salts such as ammonium carbonate is found useable by removing the cation with the cation exchange column inserted between the ODS column and the conductance detector. Thus, a few ng of tauro-and glyco-conjugated bile acids can be detected without tedious derivatization and hydrolysis.