Excited-state intermolecular proton transfer of firefly luciferin III. Proton transfer to a mild base

Steady-state and time-resolved techniques were employed to study the excited-state proton transfer (ESPT) from d-luciferin, the natural substrate of the firefly luciferase, to the mild acetate base in aqueous solutions. We found that in 1 M aqueous solutions of acetate or higher, a proton transfer (PT) process to the acetate takes place within 30 ps in both H(2)O and D(2)O solutions. The time-resolved emission signal is composed of three components. We found that the short-time component decay time is 300 and 600 fs in H(2)O and D(2)O, respectively. This component is attributed either to a PT process via the shortest water bridged complex available, ROH··H(2)O··Ac(-), or to PT taking place within a contact ion pair. The second time component of 2000 and 3000 fs for H(2)O and D(2)O, respectively, is attributed to ROH* acetate complex, whose proton wire is longer by one water molecule. The decay rate of the third, long-time component is proportional to the acetate concentration. We attribute it to the diffusion-assisted reaction as well as to PT process to the solvent.     

Determination of the plasticizer N-butylbenzenesulfonamide and the pharmaceutical Ibuprofen in wastewater using solid phase microextraction (SPME)

A rapid, inexpensive and solvent-free method for the simultaneous determination of the polyamide plasticizer N-butylbenzenesulfonamide (NBBS) and the widely used pharmaceutical Ibuprofen by solid phase microextraction (SPME) combined with gas chromatography/mass spectrometry (GC/MSD) in wastewater samples was developed. Besides the optimized analytical conditions, results of investigations with varying analytical parameters are reported. Problems, which may occur during the analytical procedure (e.g. salt deposits, adsorption phenomena, carry-over), are discussed. For the determination of Ibuprofen, it is important to carry out the extraction under acidic conditions with sufficiently buffered samples; the GC/MSD system must be very clean and well maintained. SPME allows an extraction of Ibuprofen without derivatization of its carboxylic group. For quantification in complex matrices, the standard addition technique is necessary. Limit of detection and limit of determination are 0.1 μg/L for both analytes. NBBS and Ibuprofen were detected in several raw and treated wastewater samples from municipal wastewater treatment plants in the range from < 0.1 to 3.5 μg/L.     

Fehlerquelle beim Nachweis von Gallenpigment

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Die forensische Untersuchung von Blutflecken

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Bestimmung der Harns?ure und der Xanthinbasen im Harn

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Über Methylaminoterephtalsäuren und andere Terephtalsäureabkömmlinge

Ohne ZusammenfassungFür die Ausführung der im vorstehenden mitgeteilten Krystallmessungen gestatten wir uns, Herrn Hofrat v. Lang unseren besten Dank zu sagen.     

Picosecond proton ejection: an ultrafast pH jump

The rates of proton ejection from 2-naphthol-3,6-disulfonate (pK^* = 0.5 ± 0.1) and 8-hydroxy 1,3,6-pyrene trisulfonate (pK^* = 0.4 ± 0.1) have been found to be 3.1 × 10¹⁰ s^?1 and 3.2 × 10¹⁰ s^?1, respectively. This is in keeping with the scaling of the ejection rate inversely with the excited state pK^*.     

Isometrien von Vektorräumen. II

Ohne ZusammenfassungMeinem verehrten Lehrer Helmut Wielandt zum 70. Geburtstag     

Picosecond proton transfer studies in water-alcohols solutions

Picosecond proton ejection rates from 8-hydroxy-1,3,6-pyrene trisulfonate and 2-naphthol-6-sulfonate in water-alcohol solutions have been found to decrease rapidly with increasing alcohol concentrations. It was found that the rate of proton transfer decreases more rapidly in water propanol solutions than in water ethanol solutions. This phenomenon can be interpreted in terms of water breaking structure by the organic solvent.