Pyrolysis mass spectrometry of complex organic materials.

Pyrolysis mass spectrometry in combination with computerized multivariate statistical analysis enables qualitative and quantitative analysis of nonvolatile organic materials containing molecular assemblies of a complexity and size far beyond the capabilities of direct mass spectrometry. The state of the art in pyrolysis mass spectrometry techniques is illustrated through specific applications, including structural determination and quality control of synthetic polymers, quantitative analysis of polymer mixtures, classification and structural characterization of fossil organic matter, and nonsupervised numerical extraction of component patterns from complex biological samples.

Chemometric analysis of complex hyphenated data. Improvements of the component detection algorithm.

Component detection algorithm (CODA) is a method to quickly extract the high-quality mass chromatograms from complex liquid chromatography/electrospray ionization mass spectrometry (LC/MS) data sets, saving operators hours of analysis time. It appeared, however, that mass chromatograms with a limited baseline problem were ignored. This paper describes several methods to increase the tolerance for mass chromatograms with a baseline.

Multivariate image analysis of magnetic resonance images with the direct exponential curve resolution algorithm (DECRA). Part 2: Application to human brain images.

Owing to the heterogeneity of living tissues, it is challenging to quantify tissue properties using magnetic resonance imaging. Within a single voxel, contributions to the signal may result from several types of 1H nuclei with varied chemical (e.g., -CH2-, -OH) and physical environments (e.g., tissue density, compartmentalization). Therefore, mixtures of 1H environments are prevalent. Furthermore, each unique type of 1H environment may possess a unique and characteristic spin-lattice relaxation time (T1) and spin-spin relaxation time (T2). A method for resolving these unique exponentials is introduced in a separate paper (Part 1. Algorithm and Model System) and uses the direct exponential curve resolution algorithm (DECRA). We present results from an analysis of images of the human head comprising brain tissues.

Books and Software: Quantitative analysis made easy.

A review of Chemometric Techniques for Quantitative Analysis.

Control on the absence of DEAE-polysaccharides in DEAE-sephadex purified poliovirus suspensions by pyrolysis mass spectrometry.

Poliovirus suspensions produced in microcarrier culture of primary monkey kidney cells and purified by column chromatography on DEAE-sephadex have been tested for the presence of DEAE-polysaccharides (in essence DEAE-dextran) by pyrolysis mass spectrometry. Semi-quantitative evaluation of the pyrolysis mass spectra indicates that the concentration of DEAE-dextran in the purified poliovirus concentrates is below 20 ppm i.e. the lower detection level of the method. As the final vaccines contain a 1:50 to 1:100 dilution of the tested virus suspension, the DEAE-polysaccharide concentration in the vaccine will be below 1 ppm at least. Pyrolysis mass spectrometry appeared to be a vary suitable method for control on the absence of this component.

Multivariate Image Analysis of Magnetic Resonance Images with the Direct Exponential Curve Resolution Algorithm (DECRA).

Antalek and Windig recently presented a fast method to resolve a series of NMR mixture spectra, where the contribution of the components varies with a decaying exponential [B. Antalek and W. Windig, J. Am. Chem. Soc. 118, 10,331-10,332 (1996); W. Windig and B. Antalek, Chemom. Intell. Lab. Syst. 37, 241-254 (1997)]. The method was called DECRA (direct exponential curve resolution algorithm). In this paper DECRA will be applied to two series of magnetic resonance images. The signal of one series is based upon T2 relaxation, and the other is based upon T1 relaxation. In order to evaluate the technique, the magnetic resonance images of a phantom where used. A transformation is introduced to enable the application of DECRA to a T1 series of magnetic resonance images. A separate paper in this issue will describe the application of the techniques to magnetic resonance images of the human brain. Copyright 1998 Academic Press.

Pyrolysis mass spectrometry of bacteria from infected human urine. I. Influence of culturing and antibiotics.

Curie-point pyrolysis mass spectrometry was performed on three bacterial isolates obtained from infected human urine using a novel, direct isolation method. Bacterial samples were analysed directly after isolation, as well as after free growth in broth and after exposure to solutions containing penicillin and gentamicin. The spectra of bacteria directly from urine showed no detectable contamination from urinary constituents. Discriminant analysis indicated genetic strain differences to be greater than the combined variances due to sample preparation or the growth phase. Characteristic biochemical changes related to growth or non-growth were detectable after only 2 h of incubation. The potential usefulness of pyrolysis mass spectrometry techniques for rapid susceptibility testing is discussed.