# Stability of Paracetamol Amorphized by Co-Melting with Various Cellulose Derivatives
## 3 Results
### Stability of Paracetamol after Melting  
Chromotograms of standard paracetamol and its mixtures containing 50% of the active ingredient with polymers analyzed 4 months after co-melting are shown in Figure 6. The retention time of paracetamol was 1.6 min (Figure 6, a). On the chromatograms of all physical mixtures and samples analyzed after 2 or 4 months of co-melting, only the peak  
\begin{table}
\begin{tabular}{r c c c c c c} \hline \hline \multicolumn{3}{c}{**FTIR**} & \multicolumn{3}{c}{**Raman Spectroscopy**} \\ \hline \multicolumn{2}{c}{**References [25,26]**} & \multicolumn{2}{c}{**Measured Values for**} & \multicolumn{2}{c}{**References [25,27]**} & \multicolumn{2}{c}{**Measured Values for**} \\ \hline
**Wave Number** & **Molecular** & **Peak** & **Normalized** & **Raman Shift** & **Molecular** & **Peak** & **Normalized** \\ \multicolumn{2}{c}{**(cm\({}^{-1}\))**} & **Vibration** & **(cm\({}^{-1}\))** & **Peak Intensity** & **(cm\({}^{-1}\))** & **Vibration** & **(cm\({}^{-1}\))** & **Peak Intensity** \\ \hline
3327 & OH_st_ & 3325 & 1.060 & 3110 & _as_ CH_st_ & 3102 & 1.210 \\
3161 & PH_st_ & 3160 & 1.084 & 3058 & \(s\) CH_st_ & 3062 & 1.826 \\
2926 & CH_st_ & 2929 & 0.649 & 2937 & \(s\) CH_st_ & 2930 & 1.619 \\
1653 & C=0.4, CNH_df_ & 1654 & 1.314 & 1649 & C=0.8t & 1646 & 4.076 \\
1610 & PH_st_ & 1611 & 1.247 & 1611 & NH_df_ & 1609 & 4.525 \\
1565 & CNH_df_, Ph_st_ & 1563 & 1.324 & 1559 & NH_st_, C=0_st_ & 1560 & 2.017 \\
1506 & CNH_df_, Ph_st_ & 1506 & 1.425 & 1371 & CH_df_ & 1370 & 2.314 \\
1442 & CH_df_, Ph_st_ & 1440 & 1.311 & 1324 & CH_df_\({}^{\prime\prime}\) & 1322 & 4.956 \\
1371 & CH_df_, Ph_st_ & 1369 & 1.007 & 1278 & OH_th_ & 1276 & 2.130 \\
1327 & CH_df_ & 1327 & 0.960 & 1237 & CN_st_ & 1235 & 4.290 \\
1260 & PH_df_, CN_st_ & 1259 & 1.244 & 1169 & CH_df_ & 1167 & 3.288 \\
1227 & PH_df_, CC_st_ & 1225 & 1.278 & 856 & CH_df_ & 856 & 5.698 \\
1172 & PH_df_, CO_dt_ & 1171 & 0.880 & 839 & CH_df_\({}^{\prime\prime}\) & 832 & 1.000 \\
1107 & PH_df_, CH_df_ & 1107 & 0.749 & 796 & Ph_st_ & 795 & 3.061 \\
1015 & PH_df_, CO_dt_ & 1014 & 0.656 & 649 & Ph_b_\({}^{\prime}\) & 649 & 2.932 \\
968 & PH_df_, CN_st_ & 968 & 0.672 & 501 & Ph_b_\({}^{\prime\prime}\) & 502 & 1.131 \\
856 & PH_df_, H_df_ & 857 & 0.532 & 463 & Ph_b_\({}^{\prime\prime}\) & 463 & 1.193 \\
837 & PH_df_ & 10\({}^{\prime\prime}\) & 837 & 1.000 & & & \\
810 & PH_df_, amide_df_ & 808 & 1.033 & & & & \\
795 & PH_df_, amide_df_ & 796 & 0.849 & & & & \\
715 & CNH_df_, Ph_b_\({}^{\prime\prime}\) & 713 & 0.866 & & & & \\
668 & CNH_df_, Ph_b_\({}^{\prime\prime}\) & 684 & 0.943 & & & & \\
624 & Ph_b_\({}^{\prime}\) &amide_b_\({}^{\prime\prime}\) & 625 & 0.719 & & & \\
604 & Ph_b_\({}^{\prime}\) &amide_b_\({}^{\prime\prime}\) & 603 & 0.766 & & & \\
520 & Ph_-amide_ & 518 & 0.930 & & & & \\
504 & Ph_-amide_ & 503 & 0.930 & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Paracetamol characteristic FTIR and Raman peaks.  
Figure 5: Raman spectra paracetamol (a) and mixtures containing 75%, 50% and 25% of paracetamol (respectively) with HPMC 86 (b–d), HPMC 90 (e–g), HPMC 120 (h–j) and MC (k–m).  
at the retention time consistent with standard paracetamol was observed. However, no additional peaks were observed.