an on-line uv-hplc / apci-ms (atmospheric pressure chemical ionization) tandem by a platinium c18 column with an isocratic solvent system after optimizing was applied to the separation and the identification of different carotenoids including astaxanthin, canthaxanthin, apocarotenoic ester, torularhodin and beta carotene. this method was used to identify particular carotenoids produced by newly...

The most widely used ionization techniques in liquid chromatography-mass spectrometry (LC-MS) are electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI). All three provide user friendly coupling of LC to MS. Achieving optimal LC-MS conditions is not always easy, however, owing to the complexity of ionization processes and t...

Normal-phase high-performance liquid chromatography (NP-HPLC) coupled to atmospheric pressure chemical ionization mass spectrometry (APCI-MS) allows qualitative analysis of endogenous ceramide and dihydroceramide species from crude lipid extracts utilizing chromatographic methods readily adaptable from commonly used thin layer chromatography (TLC) conditions. Qualitative information for the spe...

Atmospheric pressure chemical ionization-tandem mass spectrometry (APCI-MS/MS) was applied for the first time to the direct analysis of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in gaseous matrixes without extraction or prior chromatographic separation. Mass spectrometric characteristics of both compounds under APCI conditions and their fragmentation behavior in MS...

Electrospray ionization mass spectrometry (ESI-MS) coupled to a microreactor is an excellent tool for the investigation of reactions in solution. Here, we report the first results of our investigations into preparatively interesting electron-transfer-initiated chain reactions in solution which proceed via radical cations as reactive intermediates. The tris(p-bromophenyl)aminium hexachloroantimo...

Volatile organic compounds (VOCs) in exhaled human breath can serve as potential disease-specific and exposure biomarkers and therefore can reveal information about a subject's health and environment. Pyridine, a VOC marker for exposure to tobacco smoke, and isoprene, a liver disease biomarker, were studied using atmospheric pressure chemical ionization mass spectrometry (APCI-MS). While both m...

The analysis of brominated flame retardants (BFRs) commonly relies on the use of gas chromatography coupled to mass spectrometry (GC-MS) operating in electron ionization (EI) and electron capture negative ionization (ECNI) modes using quadrupole, triple quadrupole, ion trap, and magnetic sector analyzers. However, these brominated contaminants are examples of compounds for which a soft and robu...

glucagon like peptide-1; Ala: Alanine; Gly: Glycine; Pro: Proline; HTS: high-throughput screening; ESI: electrospray ionization; APCI: Atmospheric Pressure Chemical Ionization; pNA: p-nitroanilide; Asp: Aspartic acid; Thr: Threonine; Met: Methionine; Phe: Phenylalanine; Leu: Leucine; Ser: Serine; HOBT: Hydroxybenzotriazole ; EDCI: 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride; Me:...

Raw space-based gravitational-wave data like LISA's phase measurements are dominated by laser frequency noise. The standard technique to make this usable for science is time-delay interferometry (TDI), which cancels noise terms forming suitable combinations of delayed measurements. We recently introduced the basic concepts an alternative approach which, unlike TDI, does not rely on independent ...

A re-investigation of subaerial parts of Leontodon cichoraceus (Ten.) Sanguin. yielded the new germacrane-type sesquiterpenoid 15-beta-D-glucopyranosyl-8-[p-(beta-D-glucopyranosyloxy)phenylacetyl]-salonitenolide. The structure was established by APCI mass spectrometry and 1D- and 2D-NMR spectroscopy. A survey by HPLC-DAD and HPLC-MS gave no signs of this compound in 23 other taxa of Leontodon.