Application of a hexapole collision and reaction cell in ICP-MS Part II: Analytical figures of merit and first applications

The application of an ion-guiding gas-filled hexapole collision/reaction cell in ICP-MS has been studied to characterize the analytical figures of merit that can be achieved with this approach. For the elements investigated, application of a buffer and a reaction gas resulted in improved sensitivities which are lowest for Be with about 7 · 10⁷ cps per μg mL^–1 and highest for Ba with about ?6 · 10⁸ cps per μg mL^–1. Relative standard deviations (RSD) < 0.1% were obtained. Application of the reaction gas H₂ was used to suppress polyatomic ions caused by argon. The reduction amounted up to four orders of magnitude so that elements such as Ca, K, Cr, Fe, As and Se could be analyzed in nitric and hydrochloric acid or in methanol. Detection limits of 6 pg mL^–1 for Cr in 2% methanol, 23 pg mL^–1 for As and 9 pg mL^–1 for Se in 0.28 M HCl were achieved. For other elements detection limits ?< 1 pg mL^–1 were realized in the medium and high mass range. Accuracy was proved using the NIST 1643d standard reference material. Received: 10 May 1999 / Revised: 4 June 1999 / Accepted: 12 June 1999     

Quantitative determination of DNA adducts using liquid chromatography/electrospray ionization mass spectrometry and liquid chromatography/high-resolution inductively coupled plasma mass spectrometry

The quantitative determination of nucleotides from DNA modified by styrene oxide is described using a combination of inductively coupled plasma high-resolution mass spectrometry (ICP-HRMS) and electrospray ionization mass spectrometry (ESI-MS), both interfaced to reversed-phase high-performance liquid chromatography (HPLC). LC/ICP-MS (resolution > 1500 to discriminate against 15N16O+ and 14N16OH+) was employed to determine quantitatively the content of modified nucleotides in standard solutions based on the signal of phosphorus; phosphoric acid served as an internal standard. By means of the standard addition technique the sensitivity of the LC/ESI-MS approach was subsequently determined. Since a comparison of UV, ICP and ESI-MS data suggested that in ESI-MS the ionization efficiency of the adducts is identical within the error limits, quantitative determination of all adducts is possible. For LC/ESI-MS with single ion monitoring, the detection limit for styrene oxide adducts of nucleotides was determined to be 20 pg absolute or 14 modified in 10(8) unmodified nucleotides in a 5 micrograms DNA sample, which comes close to the best methods available for the detection of chemical modifications in DNA.     

Jump-diffusion processes in random environments

In this paper we investigate jump-diffusion processes in random environments which are given as the weak solutions of SDEs. We formulate conditions ensuring existence and uniqueness in law of solutions. We investigate the Markov property. To prove uniqueness we solve a general martingale problem for càdlàg processes. This result is of independent interest. Application of our results to generalized exponential Lévy model are present in the last section.     

The girsanov theorem and weak solutions of stochastic differential equations in the dual of a nuclear space

A version of the Girsanov theorem for the inhomogeneous Wiener process in the dual of a nuclear space is proved.It is then applied to the investigation of the existence and uniqueness of weak solutions of stochastic differential equations in this space.     

Estimates of the Green Function for the Fractional Laplacian Perturbed by Gradient

The Green function of the fractional Laplacian of the differential order bigger than one and the Green function of its gradient perturbations are comparable for bounded smooth multidimensional open sets if the drift function is in an appropriate Kato class.     

Development of a procedure for the multi-element determination of trace elements in wine by ICP-MS

An inductively coupled plasma mass spectrometric (ICP-MS) procedure has been developed for the determination of trace elements in wine. The procedure consists in simple 1+1 dilution of the wine and semi-quantitative analysis (without external calibration) using In as internal standard. Thirty-one elements at concentrations ranging from 0.1 mg mL(-1) to 0.5 ng mL(-1) can be determined by ICP-MS analysis with and without digestion. It was investigated whether a matrix effect observed for EtOH in the wine matrix can be overcome by application of a micro-concentric nebulizer with a membrane desolvator (MCN 6000). The results obtained for the MCN 6000 are compared with those obtained by use of a conventional Meinhard nebulizer. It is shown that the observed matrix effect can only be compensated by use of an internal standard for the Meinhard nebulizer, but not for the MCN 6000. Results for ICP-MS are compared with those obtained by total reflection X-ray fluorescence spectrometry (TXRF).     

Electrical properties of CoO,NiO, CuO and ZnO doped beta″-alumina

The measurements of ionic conductivity of sintered beta″-alumina samples doped with CoO, NiO, CuO and ZnO were caried out. It was found that conductivities of these samples are lower than conductivity of Li₂O stabilized beta″-alumina. For CoO, NiO, CuO as well as Li₂O stabilized beta″-alumina the bending of Arrhenius plots was observed. For samples doped with ZnO the plots were linear in whole 20°C–450°C temperature range. The doping effect on bulk conductivity was stronger than on grain boundary conductivity.     

Martin representation and Relative Fatou Theorem for fractional Laplacian with a gradient perturbation

Let $L=\Delta ^{\alpha /2}+ b\cdot \nabla $ with $\alpha \in (1,2)$ . We prove the Martin representation and the Relative Fatou Theorem for non-negative singular L-harmonic functions on $\mathcal{C }^{1,1}$ bounded open sets.     

The use of neutral cyclodextrins as additives in capillary electrophoresis for the separation and identification of propoxyphene enantiomers

A simple, efficient, and rapid method is described for separation of the enantiomers of propoxyphene by capillary electrophoresis with neutral cyclodextrins as chiral separators. This method has several advantages over the crystallization method employed by some forensic laboratories, including unambiguous results, ease of use, and smaller sample-size requirement. The method enables baseline separation of the propoxyphene enantiomers in approximately six minutes, which is less than one-third of the time required for a previously published method.