Some new features of Direct Analysis in Real Time mass spectrometry utilizing the desorption at an angle option

The present study is a first step towards the unexplored capabilities of Direct Analysis in Real Time (DART) mass spectrometry (MS) arising from the possibility of the desorption at an angle: scanning analysis of surfaces, including the coupling of thin‐layer chromatography (TLC) with DART‐MS, and a more sensitive analysis due to the preliminary concentration of analytes dissolved in large volumes of liquids on glass surfaces. In order to select the most favorable conditions for DART‐MS analysis, proper positioning of samples is important. Therefore, a simple and cheap technique for the visualization of the impact region of the DART gas stream onto a substrate was developed. A filter paper or TLC plate, previously loaded with the analyte, was immersed in a derivatization solution. On this substrate, owing to the impact of the hot DART gas, reaction of the analyte to a colored product occurred. An improved capability of detection of DART‐MS for the analysis of liquids was demonstrated by applying large volumes of model solutions of coumaphos into small glass vessels and drying these solutions prior to DART‐MS analysis under ambient conditions. This allowed the introduction of, by up to more than two orders of magnitude, increased quantities of analyte compared with the conventional DART‐MS analysis of liquids. Through this improved detectability, the capabilities of DART‐MS in trace analysis could be strengthened. Copyright © 2011 John Wiley & Sons, Ltd.     

Extremal distributions for the prophet region in the independent case

In this paper, the prophet region in the independent case is investigated. A characterization of all processes is derived, leading to extreme points of this prophet region. Then we give a game-theoretical interpretation of the results and formulate a conjecture.     

A study of the sump beaver's dental enamel

The nature of the iron-containing phase in the dental enamel of sump beaver incisors has been studied by use of Mössbauer spectroscopy. All iron atoms are found to be trivalent and to be present in particles exhibiting superparamagnetic relaxation. The iron-containing phase has Mössbauer parameters similar to those of ferritin.     

Vergleich von anionenanalysenergebnissen aus der bestimmung mittels ionenchromatographie und klassischen analysenmethoden

(Comparison of analytical results for common anions obtained by ion chromatography and classical methods.)The concentrations of chloride, nitrate, and sulphate were determined in ground-water samples by ion chromatography and by the classical titrimetric, photometric, and gravimetric methods. The results were compared by an orthogonal regression procedure. The criteria established and the tests of the confidence intervals of the orthogonal regression function indicate that the results obtained by the different analytical methods are similar for chloride and sulphate but not for nitrate.     

Retention-indices on OV-1 of approximately 170 commonly used pesticides

A screening program is reported for approximately 170 pesticides which are regularly encountered in toxicological analysis (organophosphates, carbamates, triazines, halogenated carbohydrates, phenoxycarbonic acid derivatives, and others). It is based on the retention index according to Kovats. Temperature dependence of the retention index and derivatization procedures are also studied.Dedicated in honour to Prof. Dr. Wolfgang Arnold (Hamburg) on the occasion of his 75th birthday.We are indebted to PD Dr. Hans H. Maurer (Homburg/Saar) for stimulating discussions     

Structure of the neutron-rich nucleus 37 94 rb57

A level scheme has been established for ₃₇ ⁹⁴ Rb₅₇ based on studies at the fission-product separator JOSEF ofγγ coincidences following theβ- decay of⁹⁴Kr. For the 190.7 keV level a half-life of 2.5(8) ns has been determined through the centroid-shift method. The majorβ-decay branch of⁹⁴Kr proceeds with log ft=3.7 into the 988.4 keV state in⁹⁴Rb. This transition must be of the 0⁺→1⁺ GT type involving the transitionνg_7/2→πg_9/2. IBFFM calculations have been performed for⁹⁴Rb, starting from the parametrization used in the previous IBM investigations for the isotope⁹³Rb and the isotone⁹⁶Y. A theoretical interpretation of the low-lying levels including propositions for the spins is given in a comparison to the available data.