A new two-dimensional TLC technique was developed to separate substituted anthraquinones on silica plates using n-pentanol-pyridine-methanol (6:4:3, v/v/v) and toluene-ethyl acetate-ethanol-formic acid (10:8:1:2, v/v/v/v) as eluents. The good separation power of the new technique was demonstrated by applying it to the analysis of complex anthraquinone mixtures isolated from the Scandinavian Derm ocybe sanguinea. Emodin, physcion, endocrocin, dermolutein, dermorubin, 5-chlorodermorubin, emodin-1-β-D-glucopyranoside, dermocybin-1-β-D-glucopyranoside and dermocybin, and five new, earlier in D. sanguinea unidentified compounds, 7-chloroemodin, 5,7-dichloroemodin, 5,7-dichloroendocrocin, 4-hydroxyaustrocorticone and austrocorticone, were separated and identified on the basis of Rf values, UV/Vis spectra and mass spectra.
The second method (II) was the fluorination of the protected precursor 1-(2 0 -nitro-1 0 -imidazolyl)-2-O-tetrahydropyranyl-3-O-toluenesulphonyl-propanediol, followed by a rapid removal of the protecting group. With the first method, the radiochemical yield was about 10% at the end of the synthesis (EOS), and the radiochemical purity was over 99%. The radiochemical yield in the second method was 21% (EOS) on an average, and the radiochemical purity was over 97%. When an automated commercial synthesis module was used with method II, slightly better and more reproducible yields were achieved. The improvement in the synthesis yield with the automated apparatus will be valuable when working with high activities, and therefore it is under further development.
A study was carried out on the fragmentation of 12 protonated O,O-dimethyl O-aryl phosphorothionates by tandem quadrupole mass spectrometry. Some of the studied compounds are used in agriculture as pesticides. Energy-resolved and pressure-resolved experiments were performed on the [M + H](+) ions to investigate the dissociation behavior of the ions with various amounts of internal energy. On collisionally activated dissociation, the [M + H](+) ions decompose to yield the [M + H - CH3OH](+), (CH3O)2PS(+) (m/z 125), and (CH3O)2PO(+) (m/z 109) ions as major fragments. The ions [M + H - CH3OH](+) and (CH3O)2PS(+) probably arise from the [M + H](+) ions of the O,O-dimethyl O-aryl phosphorothionates with the proton on the sulfur or on the oxygen of the phenoxy group. The origin of the hydroxy proton of the methanol fragment was in many cases, surprisingly, the phenyl group and not the reagent gas. This was confirmed by using deuterated isobutane, C4D10, as reagent gas in Cl. The fragment ions (CH3O)2PO(+) and [ZPhS](+) are the results of thiono-thiolo rearrangement reaction. The precursor ion for the ion (CH3O)2PO(+) arises from most compounds upon chemical ionization, whereas the precursor ion for the ion [ZPhS](+) arises only from a few compounds upon chemical ionization. The observed fragments imply that several sites carry the extra proton and that these sites get the proton usually upon ionization. The stability order and some characteristics of three protomers of O,O-dimethyl O-phenyl phosphorothionate were investigated by ab initio calculations at the RHF/3-21G* level of theory.
Hyphenation of liquid chromatography with nuclear magnetic resonance spectroscopy (LC-NMR) is a useful technique in the analysis of complex samples. However, application of on-flow 1H NMR spectrometry during the LC-NMR analysis usually suffers from high intensity of eluent resonances. The poor dynamic range can be improved either with use of deuterated eluents or with various signal suppression schemes. Deuterated eluents are expensive, and peak-selective signal suppression schemes are often unsatisfactory when detection of chemicals at low concentration is needed. If the analytes have a common heteronucleus, on-flow pulsed field gradient heteronuclear correlation spectrometry can offer several benefits. The analytes can be monitored selectively, while the intense nondeuterated eluent and impurity background can be effectively eliminated. In our study, on-flow one-dimensional (1D) 1H-31P heteronuclear single quantum coherence (HSQC) spectrometry was utilized in the analysis of characteristic organophosphorus degradation products of nerve agents sarin and soman during chromatographic separation. These chemicals were not detectable by UV, so their retention times were monitored using on-flow 1D 1H-31P HSQC. This enabled application of LC-NMR combined with solid-phase extraction (LC-SPE-NMR) in analysis of these organophosphorus chemicals in an alkaline decontamination solution. The analytes were extracted from the SPE cartridges with deuterated eluent, and the off-line NMR analysis was performed using a mass-sensitive microcoil probe head. The used on-flow 1D 1H-31P HSQC approach offered a high dynamic range and good detection limit (ca. 10 microg/55 nmol) with a high sampling frequency (1 point per 2 s) in the acquired pseudo-two-dimensional spectrum. No significant impurity background was present in the off-line NMR samples, and identification of the extracted analytes was straightforward.
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