Off-line combination of liquid chromatography and field desorption mass spectrometry: principles and environmental, medical and pharmaceutical applications

Analysis of Saponin Mixtures from Alfalfa (Medicago Sativa L.) Roots using Mass Spectrometry with MALDI Techniques

This model study demonstrates the value of Matrix Assisted Laser Desorption Ionization (MALDI) MS in global analysis of mixtures of saponin isolates. Unfractionated saponin extract derived from alfalfa [Medicago sativa L.] roots was analyzed. In addition, a few saponin fractions that were purified from the same extract by a series of chromatographic steps were also studied. MALDI mass spectrometry utilized TOF, TOF/TOF and QqTOF analyzers. Low-resolution fingerprints of the mixture characterized the sample in terms of a minimal number of distinct saponin components. The main species observed under MALDI-TOF and oMaldi-QqTOF MS positive ion mode conditions were sodiated pseudomolecular ions [M+Na]+. No protonated molecular ions [M+H]+ were detected. The MS/MS spectra acquired on [M+Na]+ precursor ions under conditions of collision induced dissociation (CID) were dominated by cleavages at glycosidic bonds. Product ions representing free aglycones were either absent or present at low intensities and were never observed for structures carrying an oligosaccharide bound to a sapogenin at the C3- O-position. In general, product ion series generated from CID fragmentation of glycans bound via an ether bond ( e.g., C3- O-position in medicagenic acid) were consistent with the gas phase cleavages of each of the glycosidic bonds within the oligosaccharide, thus revealing the primary structure. In contrast, glycans bound via an ester bond ( e.g., C28- O-position in MA) were released as intact sodiated species. A total of 78 pseudomolecular ions demonstrating signal-to-noise ratios above 5 were observed in the MALDI-TOF mass spectrum of unfractionated root extract from M. sativa. Molecular masses of 52 out of 78 were consistent with at least one known or novel saponin structure, with 10 of those 52 likely representing doubly sodiated saponin species. Calculated masses of the majority of the known M. sativa saponin structures were matched to experimental pseudomolecular ion masses. MS/MS analysis of unfractionated extract allowed us to propose putative structures for 51 saponins: 15 of these corresponded to the known M. sativa species, 8 to other Medicago genus species and 26 were not reported before for Medicago genus. We submit that the approach described here might serve as a high throughput strategy for evaluating effects of stressors or genetic manipulation on the overall composition of the saponin content of an organism.

Methods for speciation of metals in soils: a review

The inability to determine metal species in soils hampers efforts to understand the mobility, bioavailability, and fate of contaminant metals in environmental systems, to assess health risks posed by them, and to develop methods to remediate metal contaminated sites. Fortunately, great strides have been made in the development of methods of species characterization and in their application to the analysis of particulates and mixtures of solid phases in physics, analytical chemistry, and materials science. This manuscript highlights a selection of the analytical methods available today offering the greatest promise, briefly describes the fundamental processes involved, examines their limitations, points to how they have been used in the environmental and geochemical literature, and offers some suggested research directions in the hope of stimulating further investigation into the application of these powerful tools to the problems outlined above.

Determination of cyclophosphamide and ifosphamide in urine at trace levels by gas chromatography/tandem mass spectrometry

A specific and sensitive method based on gas chromatography/tandem mass spectrometry with on-column injection was developed to quantify simultaneously cyclophosphamide and ifosphamide in urine by using trophosphamide as an internal standard. The urine samples were extracted with diethyl ether and derivatization was performed with heptafluorobutyric anhydride. The detection limits of cyclophosphamide and ifosphamide in urine samples were 0.1 and 0.5 ng ml(-1), respectively, with a signal-to-noise ratio of 3 : 1. The sensitivity, the specificity and the low cost of the instrumentation involved make this method suitable for economical analysis on a large scale, such as for the biological monitoring of occupational exposure to cyclophosphamide and ifosphamide in production plants and in hospitals during their pharmacological use.

Identification and characterization of dolichyl dolichoate, a novel isoprenoic derivative in bovine thyroid

Inspection of the TLC pattern of the neutral lipid fraction of bovine thyroid reveals, in addition to cholesteryl esters and dolichyl fatty acid esters, the presence of a not yet identified compound in the most apolar lipid region. This unknown compound was purified on a preparative scale by silicic acid column chromatography, Lipidex-5000 gel-filtration chromatography and preparative thin-layer chromatography. By chemical (hydrolysis and reduction) and spectroscopic (ultraviolet, infrared, NMR, mass spectroscopy) methods this lipid was identified as dolichyl dolichoate. The homologue pattern was analyzed, by HPLC and FDMS, respectively.