These types of propellants are nitrocellulose-based, divided into three different categories (single, double, or triple based) each category containing key additives such as stabilizers, other energetic materials, plasticizers etc. The prediction of the lifespan of propellants is of high significance, not only for economical and performance considerations, but most importantly for safety reasons. High temperatures (>30 \({}^{\circ}\)C) or high moisture content (>65%) can lead to the degradation of stabilizers which can cause chemical instability and therefore self ignition. The National Guard Laboratory (NGL) was established in 2013, and its main purpose is to determine the stability of the propellants for the safety of civilians and military personnel. NGL uses two different techniques, Heat Flow Calorimetry (HFC) and High Performance Liquid Chromatography (HPLC), which are both validated [1]. HFC is a measure of the decomposition rate (calculated from the recorded heat flow curve) and  
Figure 27: X-ray Diffractograms of PHSu, PLA, and their copolymers (**a**), Fitting profile of PLA (**b**), DSC heating thermograms of PLA and its copolymers (**c**), and Xc by DSC and XRD against Tcc in the form of columns (**d**). yields information regarding the stability of propellants as well as the prediction of the lifespan [2]. Using HPLC, qualitative and quantitative determination of five initial and two daughter stabilizers present in the propellant before and after artificial ageing (the ageing of propellants is carried out artificially by HFC) is evaluated. From the results obtained separately from the abovementioned techniques, is possible to predict whether the propellant is suitable for safe storage. ## References  
* _NATO Allied Ordance Publication (NATO AOD) 48_, 2 nd ed. ; NATO: Brussels, Belgium, 2008. * _NATO Standardization Agreement STANAG 4582_, 1 st ed. ; NATO: Brussels, Belgium, 2007. * _Optimization of Mixed-Mode HPLC Method Intended for Analysis of Adrenergic Drugs_
* _S. Evkota_*, J. Krmar, A. Protic, M. Zecevic and B. Otasevic_
* Faculty of pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia
* Correspondence: svrkotabjana@gmail.com  
One of the most widely used drug groups refers to drugs that act through the adrenergic system. In the following research, the intent was to develop a High-Performance Liquid Chromatography (HPLC) method for the separation of adrenergic drugs. Therefore, our selected mixture of analytes contained bisoprolol (BP), fenoterole (FT), doxazosin (DOX), tetrahydroazoline (TH), and lofexidine (LOF). One of the advantages of this method lies in expanding knowledge about the analytical behaviour of lofexidine, which is limited. As all of the selected analytes are basic in nature, mixed-mode column, which includes reverse phase (RP) and weak cation exchange (WCX) interactions, was considered adequate for this HPLC analysis. The pronunciation one of two separation mechanisms depends on mobile phase content and pH, and as a consequence has the potential of selectivity modulation [1]. Analyses were performed on HPLC Thermo Acclaim Mixed Mode WCX-1 (3 \(\mu\)m, 2.1 \(\times\) 150 mm) column. During screening phase, factors of significant influence on cationic analytes behaviour were determinated. For that reason, column temperature (30-38 \({}^{\circ}\)C) and mobile phase composition parameters (acetonitrile content (30-50% \((v/v)\)), pH (3.8-5.6) and ionic strength (20-40 mM) of aqueous part of mobile phase) were selected for optimization. Design of Experiments (DoE) was used for simultaneous optimization of selected factors. Experimental plan was in line with face-centered Central Composite Design. Optimization goals were set in order to adequately separate all critical peak pairs and execute the analysis in reasonable time.