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Development of hot-melt extrusion as a novel technique for the ...

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at ~533.01 eV is <strong>the</strong> combination <strong>of</strong> C-O/-O-O bonds from polymer/drug and represents C-O-O-C or C(O)-O-O bonds [27, 28] .The N (1s) binding energy (BE) <strong>of</strong> ~402.035 eV (Fig.6.5d) in PRP suggests <strong>the</strong>protonation <strong>of</strong> <strong>the</strong> NH + group while Cl (2p) energy <strong>of</strong> ~198.035 eV significantly supports thatconclusion [26] . The N (1s) energy <strong>of</strong> ~402.8 eV in PRP/L100 extrudates represents fur<strong>the</strong>r+protonation effect <strong>of</strong> N atom <strong>as</strong> NH 4 which is described by <strong>the</strong> equation (ii) below. The N(1s) binding energy (BE) <strong>of</strong> ~402.6 eV (Fig. 5d) in DPD suggests similar effect in relation to<strong>the</strong> protonation <strong>of</strong> <strong>the</strong> NH + group while <strong>the</strong> slightly reduced Cl (2p) energy <strong>of</strong> ~197.495 eVcompared to pure PRP also significantly supports <strong>the</strong> statement.N-H+ NH 4 + / NH 2 + (next to electron withdrawing group) ...................... (ii)The N 1s peak at BE= ~402.80 eV is in good agreement with <strong>the</strong> previously observedprotonation <strong>of</strong> amide group by Beamson and Briggs [16] . The BE peak at ~402.80 eV (higher+than typically observed <strong>for</strong> amines BE= ~399 eV - 400.5 eV and much more <strong>for</strong> –NH 2+group) <strong>for</strong> N1s is an indication <strong>of</strong> C-O-NH 2 structure where<strong>as</strong> <strong>the</strong> O atom peak at ~534.40eV shows <strong>the</strong> same [16] . These results strongly indicate an interaction between <strong>the</strong> amidegroup <strong>of</strong> <strong>the</strong> API and ester/carboxyl group <strong>of</strong> <strong>the</strong> polymer (L100) through <strong>the</strong> available H-interactions or hydrogen bridges (Fig. 6.5d).Fig. 6.5d: N 1s peaks <strong>of</strong> PRP and DPD <strong>for</strong>mulations.119 | P a g e

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