液质联用技术及其应用.pptVIP

* by Li Ping * * by Li Ping * Polymer packaging films such as polyethylene and polypropylene are used for packaging materials for a wide range of products. Various polymer additives are formulated with the packaging films to modify the properties of the film, protect the film during the extrusion process, and aid the movement of the film and packaging of the product through automated packing machines. Analytical methods employing Atmospheric Pressure Ionization (API) LC/MS were developed for the polymer additives. Both electrospray and Atmospheric Pressure Chemical Ionization (APCI) modes were examined to determine which ionization technique was best for these compounds. * by Li Ping * Slip system additives are polymer additives that reduce the coefficient of friction of packaging film. This includes the movement of the packaging film through the packaging machine as well as to facilitate the packaging of the item and subsequent pack-out of the completed package into a shipping carton. These additives are fatty acid amides and different formulations vary with regard to chain length and double bond content. * by Li Ping * The behenamide sample was analyzed using positive ion APCI. The total ion chromatogram (TIC) showed three completely resolved peaks. Mass spectra from each peak indicated the presence of only one major ion in each peak. The masses of the positively-charged molecular ions differ from one another by 28 which is the mass for two methylene groups. Based on these mass differences, assignment of the three peaks can easily be made. Peak three is behenamide (C22H45NO) while peaks one and two are stearamide (C18H37NO) and arachidamide (C20H41NO), respectively. The retention times of these compounds are consistent with fatty acid amides differing in chain length with the shorter fatty acyl chains eluting earlier than the longer chain components. * by Li Ping * The total ion chromatogram from the positive ion APCI analysis of the erucamide sample s