Findings of illegal hormone preparations such as syringes, bottles, cocktails, and so on, are an important information source for the nature of the current abuse of anabolic steroids and related compounds as growth-promoting agents in cattle. A new screening method for steroids in cocktails is presented based on liquid chromatography (LC) with diode-array UV-absorbance detection and electrospray ionization time-of-flight mass spectrometry (ESI-TOFMS). Accurate mass measurements were performed at a mass resolution of 4000 using continuous introduction of a lock mass through a second (electro)sprayer. Similar experiments were carried out using dual-sprayer quadrupole time-of-flight mass spectrometry (ESI-QTOFMS/MS) at a mass resolution of 10 000 with data-dependent MS/MS acquisition; i.e. beyond an intensity threshold for the [M + H](+) ions, MS/MS spectra were automatically acquired at three different collision energies. Elemental compositions were calculated for precursor and product ions and it is shown that the combined information from LC retention behavior, UV spectra, elemental compositions, and accurate mass MS/MS spectra yield a fast impression of the steroids present in the complex mixture. Using a new software tool for structure elucidation of MS/MS spectra, an additional non-steroidal additive was identified as well.
Factors such as high polymer dispersity and variation in elemental composition (of copolymers) often complicate the electrospray ionization mass spectrometry (ESI-MS) analysis of synthetic polymers with high molar mass. In the experiments described in this study, quaternary ammonium compounds were observed to facilitate the production of low charge state pseudomolecular ions when added to the spray solution for ESI-MS. This approach was then used for the ESI time-of-flight mass spectrometry (TOF-MS) analysis of synthetic polymers. Hexadecyltrimethylammonium chloride permitted the successful analysis of poly(ethylene glycol) of 2-40 kDa, poly(propylene glycol) and poly(tetramethylene glycol) oligomers. Increasing the quaternary ammonium compounds' concentration results in the production of low charge state pseudomolecular ions. A comparison of structurally different quaternary ammonium compounds showed that the best performance is expected from large molecules with specific charge localization, which leaves the charge available for interactions. The applicability of the method for the MS analysis of other polymeric systems was also studied. In the case of poly(tetramethylene glycol), the method not only shifted the distributions to higher m/z values but also allowed the detection of high molecular weight material that was not observed without addition of the modifier to the spray solution.
Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC−ESI−MS2) was employed for the characterization of three poly(n-butyl acrylate)s. These polymers were produced at high temperature using the same initiator, tert-butyl peroxy-3,5,5-trimethylhexanoate, but in different solvents, viz. pentyl propionate, xylene and butyl acetate. Exact mass experiments performed on these polymers in an Orbitrap instrument supplied valuable information on the end group structures. Study of the data allowed identification of many reactions during the polymerization such as beta-scission and chain transfer to solvent or radical transfer to solvent from the initiator. Different fragmentation pathways were observed from the same precursor mass on MS/MS experiments, indicating the presence of isomers. The comprehensive assignment of the peaks in the LC−MS data allowed us to describe the end group distribution in a semiquantitative way. The results clearly show that the relatively reactive solvents used for polymerization have strong influences on the polymer composition.
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