Thermal FT-IR microspectroscopy for rapid detection of solid-state ion-exchange reaction between metoclopramide HCl monohydrate and potassium bromide
Wen-Ting Cheng, Shun-Li Wang and Shan-Yang Lin
The combination of Fourier transform infrared (FT-IR) microspectroscopywith a thermal analyzer was applied to quickly investigate the solid-state ion-exchange reaction of metoclopramide HCl monohydrate (MCP H2O) by clipping MCP H2O powder between two KBr or KCl pellets. The physical and ground mixtures of MCP H2O or 150 °C-preheated MCP powder and KBr or KCl powders with a weight ratio of 1 : 100 were also prepared and determined by FT-IR microspectroscopy. The samples of MCP H2O or 150 °C-preheated MCP were identified by using differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The results of present study indicate that the ion-exchange reaction was easily induced between MCP H2O and KBr by grinding and heating processes. The possible mechanism of ion-exchange reaction may take place between the HCl salt of MCP H2O and a KBr matrix by grinding or heating to yield a mixture of HCl and HBr salts of the MCP sample in the presence of hydrated water. The crystal hydrate played an important role to improve this ion-exchange reaction between MCP H2O and KBr. However, no ion-exchange reaction occurred between MCP H2O and KCl or between 150 °C-preheated MCP and KBr. The solid-state ion-exchange reaction was more easily determined by this novel thermal FT-IR microspectroscopythan other conventional methods.
FTIR microscopy, Ion-exchange, KBr, HCl monohydrate