Authors:Amal Mahmoud Abou Al Alamein, Ahmed Sayed Saad, Maha Mohammed Galal, and Hala Elsayed Zaazaa
2,6-Dimethylaniline (DMA) and o-toluidine (TOL) are considered as toxic impurities and carcinogenic metabolites as well as hydrolytic products upon degradation process for lidocaine (LD) and prilocaine (PR), respectively. The presence of such impurities above the permutable limits can adversely affect health and cause severe complications. Three different separation techniques, namely, high-performance liquid chromatography (HPLC), capillary zone electrophoresis (CZE), and thin-layer chromatography (TLC), were applied for the selective determination of the toxic compounds DMA and TOL and their intact drugs, LD and PR, respectively. The proposed HPLC method was carried out on Inertsil ODS 3 column (50 mm × 4.6 mm, 5 μm), utilizing a green mobile phase consisting of ethanol and 34 mM disodium hydrogen phosphate (20:80, v/v; pH = 6 adjusted using o-phosphoric acid). The flow rate was 1 mL min−1 with UV detection at 220 nm. The CZE separation was performed using 50 mM monobasic sodium phosphate (pH = 2.5), and voltage programming started with 22 kV for the first 6.7 min down to 18 kV from 6.9 min till 10 min. The suggested TLC method was achieved on TLC plates pre-coated with silica gel 60 F245 using a developing solvent containing toluene‒chloroform‒ethanol‒triethylamine (5:5:1:0.1, by volume). These methods were validated with respect to linearity range, accuracy, precision, limit of detection, limit of quantification and robustness and were successfully applied for the determination of the two drugs in pure form and in pharmaceutical dosage form. A comparative study was held between the three chromatographic methods to evaluate the selectivity of the separation and the sensitivity, accuracy, and precision of the quantification.
mechanical analysis (DMA) local thermal analysis (micro- and nano-thermal analysis) coupled thermal analysis techniques
Opening: Prof. Dr G. Liptay, the author of the well-known Atlas of Thermoanalytical Courves (Hungary) Joseph
Authors:K. Sreekanth, M. Kondaiah, D. Sravana Kumar, and D. Krishna Rao
. Equimolar mixture of ethanol (EOH) and isopropyl alcohol (IPA)/isobutyl alcohol (IBA)/isoamyl alcohol (IAA) is first prepared and this solution has been used to prepare the liquid mixtures with N,N -dimethyl acetamide (DMA) so that over the entire
Applications of the new 980 Dynamic mechanical analyser (DMA) to the study of thermoplastic polymers, thermosetting polymers and metal glasses have been discussed in this paper. This instrument has also been used to study impact modified thermoplastics  elastomers  and metals. DMA is one of the thermo-analytical thechniques available to the research or quality control chemist for evaluating the mechanical properties of materials. With the introduction of the 980 it is anticipated that the disadvantages due to long operation time and complexity inherent in older instrumentation will no longer hold back progress towards the full realisation of the technique.
Blends of poly(ether-sulfone) (PES) and poly(phenylene sulfide) (PPS) with various compositions were prepared using an internal
mixer at 290C and 50 rpm for 10 min. The thermal and dynamic mechanical properties of PES/PPS blends have been investigated
by means of DSC and DMA. The blends showed two glass transition temperatures corresponding to PPS-rich and PES-rich phases.
Both of them decreased obviously for the blends with PES matrix. On the other hand, Tg of PPS and PES phase decreased a little when PPS is the continuous phase. In the blends quenched from molten state the cold
crystallization temperature of PPS was detected in the blends of PES/PPS with mass ratio 50/50 and 60/40. The melting point,
crystallization temperature and the crystallinity of blended PPS were nearly unaffected when the mass ratio of PES was less
than 60%, however, when the amount of PES is over 60% in the blends, the crystallization of PPS chains was hindered. The thermal
and the dynamic mechanical properties of the PPS/PES blends were mainly controlled by the continued phase.
Authors:Gordana Marković, Suzana Samaržija-Jovanović, Vojislav Jovanović, and Milena Marinović-Cincović
The properties of filled polymers depend on the properties of the matrix and the filler, the concentration of the components
and their interactions. In this research we investigated the rheological and mechanical properties and thermal stability of
polychloroprene/chlorosulfonated polyethylene (CR/CSM) rubber blends filled with nano- and micro-silica particles. The density
of the nano-silica filled CR/CSM rubber blends was lower than that of the micro-silica filled samples but the tensile strength
and elongation at break were much higher. The nano-silica filled CR/CSM rubber blend has higher Vr0/Vrf values than micro-silica composites and show better polymer–filler interaction according to Kraus equation. The nano-silica
filled CR/CSM rubber blends were transparent at all filler concentration, and have higher glass transition values than micro-silica
filled compounds. The higher values of the glass transition temperatures for the nano- than the micro-filled cross-linked
systems are indicated by DMA analysis. The nano-filled cross-linked systems have a larger number of SiO–C links than micro-filled
cross-linked systems and hence increased stability.
Authors:Naomi Warashina, Masahiro Tsuchiya, Kaori Ishimaru, and Takakazu Kojima
soluble in nonionic polar solvents, such as N , N -dimethylacetamide, DMA, dimethylsulfoxide, DMSO, etc., [ 1 , 2 ]. Aromatic polyamides having good solubility are industrially important, because of their ease of fabrication. Many aromatic polyamides
Authors:T. S. Belal, M. M. Bedair, A. A. Gazy, and K. M. Guirguis
This study presents a selective high-performance liquid chromatography (HPLC) with diode array detection (DAD) method for the simultaneous estimation of diclofenac sodium and lidocaine hydrochloride in presence of four of their related substances and potential impurities, namely, 2,6-dimethylaniline (DMA), 2,6-dichloroaniline (DCA), N-phenyl-2,6-dichloroaniline (PDCA), and N-chloroacetyl-N-phenyl-2,6-dichloroaniline (CPDCA). Some of these related substances are reported as degradation products as well. Effective chromatographic separation was achieved using Waters Symmetry C18 column, (3.9 × 150 mm, 5 μm particle size) with gradient elution of the mobile phase composed of 0.05 M orthophosphoric acid and acetonitrile. The gradient elution started with 5% (by volume) acetonitrile, ramped up linearly to 65% in 5 min then kept constant till the end of the run. The mobile phase was pumped at a flow rate of 1.5 mL min−1. The multiple wavelength detector was set at 220 nm, and quantification of both drugs was based on measuring their peak areas. The retention times for lidocaine and diclofenac were about 5.5 and 9.5 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. Calibration curves were linear in the ranges of 10–200 μg mL−1 for both drugs with correlation coefficients not less than 0.9998. The proposed method proved to be selective by resolution of the two drugs from their related substances and potential impurities. The validated HPLC method was successfully applied to the analysis of this binary mixture in the combined formulation (ampoules dosage form), and the assay results were favorably compared with a previously reported HPLC method. The proposed method made use of DAD as a tool for peak identity and purity confirmation.
Chapter 5 is devoted to dynamic mechanical analysis (DMA) written by Richard P. Chartoff, Joseph D. Menczel, and Steven H. Dillman. DMA is one of the most powerful techniques to characterize relaxation processes in polymeric materials. The
described, and included the application of the full range of thermoanalytical techniques, differential scanning calorimetry (DSC), thermogravimetry (TG), thermomechanical analysis (TMA), dielectric analysis, dynamic mechanical analysis (DMA), and micro