Gel permeation chromatography of nitrocellulose (NC) and NC containing substances III. Recent results from a continued parameter study on the GPC of NC samples

摘要

In the course of the update of STANAG 4178 "Assessing the Quality of Nitrocellulose Deliveries from one NATO Nation to Another" a multinational round robin (RR) test on GPC of NC (nitrocellulose) was performed to ensure the formulation of an analytical sound procedure included in this STANAG Ed.2 /1, 2, 3/. In addition to the RR program some further investigations were conduced concerning two faster sample preparation methods and the use of a modem and efficient GPC. Four different NC with N content ranging from 11.7 to 13.55 mass-% have been used. These results are compared with the ones from the RR procedure. In this case the outcome was a good agreement between RR procedure and two fast preparation methods. Several drying methods for the water wet NC have been applied. A higher thermal impact in the drying procedure affects the mean molar masses. The thermal load during drying should be as low as possible in order to get the necessary maximum allowed water content preferably of about 0.5 to 1 mass-%. In order to ensure a good data evaluation of the elugrams and to compensate for flow fluctuations toluene was used as internal standard. But toluene proved to be a not suitable substance for this purpose. Interactions between toluene and NC seem to influence the evaluation results. The separation of the polymeric NC on the columns was changed by addition of 0.1 mass-% trifluoroacetic acid (TFA) to the eluent.