Tapio Kotiaho

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Using a cellulose dialysis membrane and aqueous solutions of common drugs as a proof-of-principle example, we demonstrate that solid but permeable and flexible membranes can be used as interfaces for the direct analysis of solution constituents via easy ambient sonic-spray ionization mass spectrometry. This new combination of MS techniques, herein termed(More)
In this study, tetra- (#47), penta- (#99), and decabrominated (#209) diphenyl ethers were exposed (in isooctane) to summer sunlight at 60 degrees N, where their photochemical half-lives ranged from 0.6 to 203 h. Apparent quantum yields, ranging from 0.16 to 0.28, were applied to optical models to calculate the rates of direct photochemical decomposition at(More)
Purpose. The purpose of the study was to evaluate several n-in-one cocktails of heterogeneous compounds to increase the throughput of permeability studies across Caco-2 monolayers, to investigate the reliability and applicability of the method, and to develop fast and sensitive analysis for the compounds. Compounds with potential interactions in efflux(More)
This review presents a brief overview of recent developments in miniaturization of analytical instruments utilizing microfabrication technology. The concept 'Micro-Total Analysis Systems micro-TAS)', also termed 'Lab-on-a-chip', and the latest progresses in the development of microfabricated separation devices and on-chip detection techniques are discussed.(More)
Two membrane inlet mass spectrometric (MIMS) methods for determining phenolic compounds in water are described and compared, namely direct analysis and analysis after acetylation of the phenolic compounds. Direct analysis of phenolic compounds in water is a very simple and rapid method and detection limits are relatively low (from 30 mug 1(-1) for phenol to(More)
The study of the metabolic fate of drugs is an essential and important part of the drug development process. The analysis of metabolites is a challenging task and several different analytical methods have been used in these studies. However, after the introduction of the atmospheric pressure ionization (API) technique, electrospray and atmospheric pressure(More)
Aqueous ozonation of the 22 most common amino acids and some small peptides were studied by electrospray mass (ESI-MS) and tandem mass spectrometry. After 5 min of ozonation only His, Met, Trp, and Tyr form oxidation products clearly detectable by ESI-MS. For His, the main oxidation product is formed by the addition of three oxygen atoms, His + 30; for Met(More)
An ambient ionization technique for mass spectrometry, desorption atmospheric pressure photoionization (DAPPI), is presented, and its application to the rapid analysis of compounds of various polarities on surfaces is demonstrated. The DAPPI technique relies on a heated nebulizer microchip delivering a heated jet of vaporized solvent, e.g., toluene, and a(More)
The ionization mechanism in dopant-assisted atmospheric pressure photoionization and the effect of solvent on the ionization efficiency was studied using 7 naphthalenes and 13 different solvent systems. The ionization efficiency was 1-2 orders of magnitude higher with dopant than without, indicating that the photoionization of the dopant initiates the(More)
The performance of desorption electrospray ionization (DESI) in the analysis of a group of pharmaceuticals and their glucuronic acid conjugates is reported. The suitability of different sprayer solvents and different surfaces was examined. In the positive ion mode, water/methanol/trifluoroacetic acid performed best, whereas, in the negative ion mode,(More)