Highly selective reversed phases (C-30 phases) are self-packed in 250,mum inner diameter fused-silica capillaries and employed for capillary HPLC separation of shape-constrained natural compounds (tocopherol homologues, vitamin E). Miniaturized hyphenated systems such as capillary HPLC-ESI-MS (positive ionization mode) and, with special emphasis, continuous-flow capillary HPLC-NMR are used for structural determination of the separated compounds. Despite the small amount of sample available (1.33 mug of each tocopherol), the authors have been able to monitor the capillary HPLC separation under continuous-flow H-1 NMR conditions, thus allowing an immediate peak identification. Further structural assignment was carried out in the stopped-flow NMR mode as shown, for example, by a 2D H-1,H-1 COSY NMR spectrum of cc-tocopherol. We demonstrate in this paper the considerable potential of hyphenated capillary separations coupled to MS and NMR for the investigation of restricted amounts of sample.

The aim of the investigation was to assess a stable isotope method for determining the relative bioavailability of food-derived lutein in humans. Subjects were administered a single dose of deuterium-labeled carotenoids from intrinsically labeled spinach or collard green; 10 mL blood samples were drawn at various time points over a 34 days period. The vegetables had been hydroponically grown using 25 atom-% deuterated water. Lutein molecules in the vegetables were partially deuterated with a highest abundance isotopomer at M0 + 8 (unlabeled molecular mass, M0, plus 8 additional mass units from 8 deuterium atoms in the molecules). This allowed labeled lutein to be distinguished from endogenous lutein in serum samples after consuming the labeled meal. The presence of labeled lutein in the circulation was determined by liquid chromatography-mass spectrometry (LC/MS) equipped with an atmospheric pressure chemical ionization (APCI) interface. The quantification of the labeled lutein in serum samples enabled the calculation of the enrichment for each time point after the dose; these values were plotted vs. time to generate absorption-clearance curves for each of the subjects. Area under the curve analyses of four different subjects (integrated over 29 days) yielded serum lutein responses of 128, 145, 149, and 262 μg-day/mg dietary lutein, following an acute dose of spinach containing 15.4, 18.8, 18.8 and 9.8 mg labeled lutein, respectively. This technique will facilitate the study of lutein bioavailability from different foods of diverse carotenoid composition and/or following various food preparation procedures.

The derivatization reaction of the mycotoxin moniliformin with 1,2-diamino-4,5-dichlorobenzene was previously introduced to improve distinctly the sensitivity of an assay applying high-performance liquid chromatography prior to fluorescence detection. In the course of the implementation of this derivatization approach into a liquid chromatographic/mass spectrometric method, an unexpected derivatization product has now been discovered by mass spectrometry. In order to elucidate its structure, detailed investigations with liquid chromatography/tandem mass spectrometry and liquid chromatography coupled on-line with NMR spectroscopy were performed. These studies give evidence for a heterocyclic structure that has been formed by the loss of one water and one carbon monoxide molecule. A reasonable mechanism for this derivatization reaction is proposed.

The carotenoids lutein and zeaxanthin have been identified as the macular pigments of the human retina. Nutritional epidemiological reports indicate that high consumption of fruits and vegetables rich in these carotenoids is correlated with reduced risk of some illnesses, e.g. agerelated macular degeneration (AMD).

Gingival samples treated with toothpastes containing tocopherols (vitamin E) were investigated employing HPLC chromatography. The aim was to verify that vitamin E is actually enriched in the tissue, which could have beneficial effects on oral health. After determination of the tocopherols available in the toothpastes, control samples from healthy test persons and subjects suffering from gingivitis were analyzed. Subsequently, gingival tissues from diseased test persons who treated their teeth with the toothpastes containing tocopherols using various kinds of concentrations or applications were investigated. The first step of the analysis was a fast and careful extraction. employing matrix solid-phase dispersion (MSPD). Afterward, the separation of the different tocopherol homologues existing was performed by HPLC chromatography on highly selective C-30 RP phases. The identification of the tocopherol homologues was performed using the on-line coupling of HPLC with NMR spectroscopy and mass spectrometry.

The core-shell structure of lycopene micronizates can be verified by employing a combination of solid-state and suspended-state NMR spectroscopy. The type of molecular aggregation of carotenoid nanoparticles can be clearly determined from their characteristic fingerprint pattern in the solid-state NMR spectra.