Application of a secondary ion mass spectrometer as a detector in liquid chromatography

Recently developed new techniques of ion formation from organic solids may become very useful in the application of mass spectrometers as detector units in liquid chromatography. Details of a liquid chromatograph mass spectrometer coupling device are presented. Some features of this device, combined with a quadrupole secondary ion mass spectrometer, are demonstrated experimentally by the analysis of aqueous solutions of leucine and cytosine. It is demonstrated that the sensitivity of the liquid chromatography secondary ion mass spectrometry combination covers the concentration range occurring in liquid chromatography.     

Comparison of ‘soft ionization’ techniques with electron impact mass spectrometry for desoxinojirimycin and folic acid derivatives

Seven desoxinojirimycin and three folic acid derivatives were investigated using the soft ionization techniques of desorption chemical ionization (DCI), laser desorption (LAMMA), field desorption (FD), secondary ion mass spectrometry (SIMS) and fast atom bombardment (FAB). The mass spectra were compared with electron impact (EI) spectra and interpreted in terms of their suitability for analytical purposes.     

The instability of some gradient methods for ill-posed problems

Summary For the solution of linear ill-posed problems some gradient methods like conjugate gradients and steepest descent have been examined previously in the literature. It is shown that even though these methods converge in the case of exact data their instability makes it impossible to base a-priori parameter choice regularization methods upon them.     

Über die Stabilisierung von Mizellen in nichtpolaren Lösungsmitteln durch löslichmachende Ionen und polare Flüssigkeiten

Ohne Zusammenfassung     

Identification and structural elucidation of new caprazamycins from Streptomyces sp. MK730-62F2 by liquid chromatography/electrospray ionization tandem mass spectrometry

The development of reliable analytic methods, capable of separating mixtures of secondary metabolites as well as providing structural information, is essential for the investigation of secondary metabolites, e.g. from Streptomyces. Here we report a liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method using a triple quadrupole mass analyzer for the structural elucidation of caprazamycins and liposidomycins from culture extracts of the wild-type producer strains. Comparison of the fragmentation patterns in positive as well as in negative ionization mode revealed several characteristic product ions used for identification of six new caprazamycins. Furthermore, a chromatographic method for the purification of nucleosides from cell cultures using a boronic acid gel was adapted for the partial purification of the culture extracts.