Thermal desorption ToFMS

In direct insertion techniques, reproducibility is the main obstacle in developing a reliable analytical technique. One of the many variables to take into account is sample shape. A compact sample with minimal surface area is ideal [64]. Direct mass-spectrometric characterisation in the direct insertion probe is not very quantitative, and, even under optimised conditions, mass discrimination in the analysis of polydisperse polymers and specific oligomer discrimination may occur. For nonvolatile additives that do not evaporate up to 350 °C, direct quantitative analysis by thermal desorption is not possible (e.g. Hostanox 03, MW 794). Good quantitation is also prevented by contamination of the ion source by pyrolysis products of the polymeric matrix. For polymer-based calibration standards, the homogeneity of the samples is of great importance. Hyphenated techniques such as LC-ESI-ToFMS and LC-MALDI-ToFMS have been developed for polymer analyses in which the reliable quantitative features of LC are combined with the identification power and structure analysis of MS. 

Combined thermal desorption/pyrolysis using PTV-HTGC-FID/ToFMS (1)... 

DP-MS suffers from system saturation sample loads of a few ig are to be used. DP-ToFMS equipped with El and FI sources is a thermal separation technique for solids which allows exact mass determination (Section 6.3.3). In order to detect and characterise polymer fragments of higher molecular weight, techniques such as DCI, in which the sample is thermally desorbed by the filament on which it is directly deposited, and laser desorption... 

Californium-252 ( Cf) plasma desorption (PD) ionization, introduced in 1974 by Torgerson and co-workers [15], soon found applications for the analysis of large nonvolatile, polar, and thermally labile molecules [16,17]. Because of the pulsed nature of the plasma beam, PD is well adapted to TOF mass spectrometry. The basic concept of PD-TOFMS is illustrated in Figure 2.5. In this technique, the sample is deposited as a solid film on a thin aluminum foil or other suitable... 

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